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Coatings consisting in gentamicin-containing nanocapsules have been synthetized by means of an aerosol-assisted atmospheric pressure plasma deposition process. The influence of different parameters affecting the process has been extensively investigated by means of a morphological and chemical characterization of the coatings. Scanning electron microscopy highlighted the presence of nanocapsules whose size and abundance depend on power input and deposition time. A detailed analysis carried out with matrix-assisted laser desorption ionization coupled to high-resolution mass spectrometry allowed to detect and identify the presence of gentamicin embedded in the coatings and its rearrangement, as a result of the interaction with the plasma. The release of gentamicin in water has been monitored by means of UV-vis fluorescence spectroscopy, and its biological activity has been evaluated as well by the disk diffusion assay against Staphylococcus aureus and Pseudomonas aeruginosa. It is confirmed that the antibacterial activity of gentamicin is preserved in the plasma-deposited coatings. Preliminary cytocompatibility investigations indicated that eukaryotic cells well tolerate the release of gentamicin from the coatings.

Biofilms contribute to persistent bacterial infections as well as formidable resistances to conventional antibiotics. However, it is still a major challenge to establish an advanced antibacterial nanoplatform that can efficiently eradicate biofilms while overcoming bacterial resistances. Taking advantage of the stimuli-responsive technique and the magnetic guidance strategy, here we present a highly efficient nanoplatform for planktonic inactivation and biofilm disruption. The multilayer films consisting of antibiotic gentamicin (Gen), tannic acid, and silver nanoparticles (AgNPs) were fabricated and coated on magnetic nanoparticles via electrostatic interactions. To achieve controlled drug release and improved biocompatibility, biodegradable hyaluronic acid was capped on the outer surface as a responsive shell. In vitro release profiles suggested that the nanocomposites showed both enzyme and pH-responsive release properties. The nanoplatform could be employed as a powerful nanocarrier for small molecular Gen and AgNPs delivery and on-demand release in response to bacterial infection microenvironment. The nanocomposites also showed satisfying antibacterial capacities against planktonic Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Intriguingly, with magnetic field navigation (NdFeB, 2000 gauss), the nanocomposites could be guided to handily penetrate into S. aureus biofilm and performed dual-responsive release, showing significantly enhanced biofilm disruption. Moreover, excess reactive oxygen species production resulting from the nanocomposites contributed to the decomposition of biofilm matrix and ultimate biofilm eradication. As a consequence, the ingenious antibacterial nanoplatform could be promising for combating biofilm infections while overcoming bacterial resistances with extra environmental factors such as magnetic field.

Purpose: Copal® spacem is a new PMMA bone cement for fabricating spacers. This study compares elution of gentamicin, elution of vancomycin, and compressive strength of Copal® spacem and of Palacos® R+G at different vancomycin loadings in the powder of the cements. We hypothesized that antibiotic elution of Copal® spacem is superior at comparable compressive strength., Methods: Compression test specimens were fabricated using Copal® spacem manually loaded with 0.5 g gentamicin and additionally 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (COP specimens) and using 0.5 g gentamicin premixed Palacos® R+G manually loaded with 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (PAL specimens). These specimens were used for determination of gentamicin and vancomycin elution (in fetal calf serum, at 22°C) and for determination of compressive strength both prior and following the elution tests., Results: Cumulative gentamicin concentrations (p < 0.005) and gentamicin concentration after 28 days (p ≤ 0.043) were significantly lower for COP specimens compared to PAL specimens. Cumulative vancomycin concentrations were significantly higher (p ≤ 0.043) for COP specimens after the second day. Vancomycin concentrations after 28 days were not significantly higher for the Copal specimens loaded with 2 g and 4 g of vancomycin. Compressive strength was not significantly different between COP specimens and PAL specimens before elution tests. Compressive strength after the elution tests was significantly lower (p = 0.005) for COP specimens loaded with 2 g of vancomycin., Conclusion: We could not demonstrate consistent superior antibiotic elution from Copal® spacem compared to Palacos® R+G for fabricating gentamicin and vancomycin loaded spacers. The results do not favor Copal® spacem over Palacos® R+G for the use as a gentamicin and vancomycin biantibiotic-loaded spacer.

To solve the Ti implants-associated infection and poor osseointegration problems, we have constructed the AgNPs/gentamicin (Gen)-loaded silk fibroin (SF) coating with acceptable antibacterial and osteogenic aptitude. Nevertheless, due to uncontrollably sustained drug release, this bactericidal coating encountered some tricky problems, such as local high Ag concentration, short life-span and potential cytotoxicity. In this work, a chitosan (CS) barrier layer was constructed to prebuilt the SF-based film by two means, dip-coating (DCS) and spin-coating (SCS). Intriguingly, the CS barrier layer constructed by spin-coating highly improved the hydrophilic and protein-absorbed performances. As verified in the release profile, both coatings showed a prolonged and pH-dependent pattern of Ag + with an accelerated release in acidic condition. Also, the multilayer coating with a SCS barrier layer showed an apparent bacteria-trigged antibacterial and biofilm-inhibited performances, whereas the improvements of antibacterial abilities of DCS coating were limited. The mechanisms could be explained that the pH decrease induced by the attachment and proliferation of bacteria triggered collapse of CS barrier layer, accelerating the release of bactericides. Moreover, benefitted from pH-dependent release behavior of Ag and bioactive SCS layer, functional coatings highly enhanced the initial adhesion, migration and proliferation of preosteoblast MC3T3-E1 cells, and subsequently accelerated osteoblast differentiation (alkaline phosphatase production). A relevant aspect of this work was to demonstrate the essential effect of reasonable construction of self-defensive barrier layer in achieving the balance between the high-efficiency bacterial killing and osteogenic activity, and highlighted its excellent potential in clinical applications.

In this work, an HPLC/MS/MS method for determination of gentamicin C components in fish tissues was developed based on strong cation exchange solid-phase extraction (SPE) purification coupled with Hypercarb chromatographic column in separation mode. Sample was extracted using trichloroacetic acid aqueous solution containing EDTA. Ion-pairing reagents were not needed because of the "graphite polarity retention effect" of the Hypercarb chromatographic column. HPLC-MS/MS was performed in multiple reaction monitoring (MRM) mode for simultaneous qualitative and quantitative analyses (using matrix external standard) of gentamicin C components in fish tissues. Good linearity was obtained for the target analytes within the concentration range from 0.0100 to 0.500 mg/L. The limits of quantification (LOQ) of this method were 10.0, 20.0, and 20.0 μg/kg for C1, C1a, and sum of C2 + C2a, respectively. The average recoveries of gentamicin C components were 80.0%-110% when spiked at three levels with the blank carp (Cyprinus carpio) matrix, and the relative standard deviations (RSD) were all less than 15% (n = 6). In addition, for the features of simple operation, high sensitivity and good reproducibility, the proposed method has been successfully applied for detection of gentamicin residues in fish tissues during actual breeding., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Implant-related bacterial infections remain a serious problem that is not solved yet. Herein we combined several antibacterial agents to achieve synergistic effects and broader protection of widely used metallic implants. Titanium samples with microcontainers for drug, produced by selective laser sintering, were coated with Ag-doped biocompatible and bioactive TiCaPCON film and loaded with an antibiotic (gentamicin or a mixture of gentamicin and amphotericin B). Bactericide release tests demonstrated that the release rate of one bactericide agent (Ag + ions or gentamicin) depended on the presence of the other antibacterial component. The antibacterial activity of the biocide-doped samples was evaluated against clinically isolated Escherichia coli O78 (E. coli), Staphylococcus aureus (S. aureus) bacteria, and Neurospora crassa wt-987 (N. crassa) spores. It was found that samples loaded with low gentamicin concentration (0.2 and 0.02 mg/cm 2 ), i.e. 10 and 100 times less than the standard gentamicin concentration (2 mg/cm 2 ), demonstrated a superb antibacterial activity against E. coli bacteria. We showed that a crosslinking reaction between gentamicin and TiCaPCON film proceeded either through the formation of amide bonds or via the electrostatic interaction between amine groups of gentamicin and COOH groups of TiCaPCON and led to the formation of relatively stable drug/film conjugates that prevented a rapid dissolution of gentamicin and ensured its long-term (for 72 h) antibacterial protection. Leaching of silver ions provided an effective antibacterial protection after the depletion of the drug reservoirs. The obtained results clearly show a synergistic antibacterial action of Ag + ions and gentamicin against S. aureus bacteria. In addition, in the presence of Ag + ions, the antifungal activity of samples loaded with a mixture of gentamicin and amphotericin B against N. crassa fungus was observed to increase. Thus, it is demonstrated that silver can be successfully coupled with different types of antibiotics to provide innovative hybrid metal-ceramic bioconstructions that are able to deliver precise doses of bactericide agents within a certain period of time and are equally effective against Gram-negative E. coli bacteria, Gram-positive S. aureus, and N. crassa fungus., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To endow orthopaedic implants with satisfactory antibacterial properties, the design and development of antibiotic coating on the surface of implants is highly desired. In this work a novel and facile strategy was developed to form pH-responsive layer-by-layer (LbL) films implanted with polymeric micelles as nano-vehicles loaded with charge-weak antibiotic drugs, enabling high drug loading efficiency. Negatively charged tobramycin (Tob)-embeded heparin miscells (HET) and positively charged chitosan (CHT) were exploited as a pH-responsive LBL multilayer building block, respectively. The formation mechanism and pH-stimulated release behavior of the Tob-contained heparin micelles were studied. The characterization on the morphologies, chemical compositions and hydrophilicity of the modified surface confirmed the successuful deposition of the Tob-loaded CHT/HET multilayers coatings on the polydopamine-modified Ti surface. The drug release profiles displayed fast release at pH 7.4 and slow release after exposure to weakly acidic environments. Antibacterial tests indicated that the Tob-embed CHT/HET nanostructured multilayers not only strongly inhibited initial bacterial adhesion, but also disruptted biofilm formation. Particularly, this functional coatings showed "long-term antibacterial" pattern in acid condition. Meanwhile, MC3T3 cells showed acceptable adhesion, spread and proliferation on the multilayer coatings in cytocompatible studies. In a word, these multilayer coatings incorporated with a wide variety of antibiotics show promisiong applications in preventing postoperative infection and resolving unmet clinical need., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Aim: Lactoperoxidase (LPO) is an essential protein with broad spectrum antimicrobial activity present in mammalian milk. It imparts immunity to infants against wide range of pathogenic infections. Several in vitro studies have shown inhibition of LPO activity by pharmaceutical compounds including commonly used antibiotics such as ampicillin and gentamicin, and molecules like prednisolone, norepinephrine, etc. Prescription of such drugs to lactating mothers might have adverse health effects on infants. The aim of our study was the elucidation of the structural aspects of the inhibitory mechanism of ampicillin, gentamicin, amoxicillin, prednisolone and norepinephrine on LPO., Material and Methods: Three dimensional structure of camel LPO (cLPO) was developed using homology modeling and used for in silico experimental studies. The Schrödinger induced fit docking along with binding affinity estimation experiments were performed. The cLPO and Ligands were prepared using Protein Preparation Wizard and Ligprep modules available in Schrodinger suite. For estimating Binding affinity Prime Molecular Mechanics with Generalized Born and Surface Area (MMGB-SA) module was used., Key Results: The five drug ligands formed three to five hydrogen bonding interactions with cLPO. Amino acids Arg-231, Asp-232, Ser-370, Arg-371 and Glu-374 of cLPO were crucial for these interactions. The binding affinity values for gentamicin were highest and for norepinephrine were the lowest., Significance: This study concludes that the five drug molecules show potential ability to inhibit the LPO activity. Further, a very high sequence similarity of cLPO with human LPO imparts high significance to these conclusions in relation to human health especially in new born infants., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Mesoporous bioactive glass (MBG) has a greater surface area and pore volume than conventional BG. Hence, MBG is useful as a drug delivery carrier. Previously, MBG has been fabricated as dense or porous blocks. Compared to blocks, microbeads have a greater flexibility to fill different-shaped cavities with close packing. Moreover, fibrous materials have proven to increase cell attachment and differentiation because they mimic the three-dimensional structure of the natural extracellular matrix (ECM). Macroporous materials possess porous structures with interconnecting channels that allow the invasive growth of cells and capillaries. Hence, the aim of this study was to fabricate macroporous microbeads containing MBG nanofibres (MMBs). We used poly(methyl methacrylate) (PMMA) microspheres as the macroporous template in the process and removed the PMMA microspheres after the calcination treatment. Scanning electron microscopy imaging showed multiple pores on the surface of the MMBs, and a micro-computed tomography image showed the presence of pores throughout the entire microbead. The cellular attachment of MG63 osteoblast-like cells was considerably higher on the MMBs than on glass beads after culturing for 4 h. However, the cell viability greatly decreased after culturing for 1 day. We speculated that the release of a high concentration of calcium ions from the MMBs decreased the cell viability. To improve the cell viability, we modified the MMBs by immersing the MMBs in a simulated body fluid to fabricate a thin apatite layer on the surface of the MMBs. The apatite-modified MMBs (Ap-MMB) decreased the release of calcium ions and improved the cell viability. In an animal study, the bone defect in the control group did not recover. In contrast to the control group, the Ap-MMBs in the defect were nearly filled with new bone. The results show that the Ap-MMBs have great potential in osteogenesis for bone tissue engineering., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Combating implant-associated infections is an urgent demand due to the increasing numbers in surgical operations such as joint replacements and dental implantations. Surface functionalization of implantable medical devices with polymeric antimicrobial and antifouling agents is an efficient strategy to prevent bacterial fouling and associated infections. In this work, antimicrobial and antifouling branched polymeric agents (GPEG and GEG) were synthesized via ring-opening reaction involving gentamicin and ethylene glycol species. Due to their rich primary amine groups, they can be readily coated on the polydopamine-modified implant (such as titanium) surfaces. The resultant surface coatings of Ti-GPEG and Ti-GEG produce excellent in vitro antibacterial efficacy toward both Staphylococcus aureus and Escherichia coli, while Ti-GPEG exhibit better antifouling ability. Moreover, the infection model with S. aureus shows that implanted Ti-GPEG possessed excellent antibacterial and antifouling ability in vivo. This study would provide a promising strategy for the surface functionalization of implantable medical devices to prevent implant-associated infections.

Tailoring nanofibrous matrices-a material with much promise for wound healing applications-to simultaneously mitigate bacterial colonization and stimulate wound closure of infected wounds is highly desirable. To that end, a dual-releasing, multiscale system of biodegradable electrospun nanofibers coated with biocompatible micellar nanocarriers is reported. For wound healing, transforming growth factor-β1 is incorporated into polycaprolactone/collagen (PCL/Coll) nanofibers via electrospinning and the myofibroblastic differentiation of human dermal fibroblasts is locally stimulated. To prevent infection, biocompatible nanocarriers of polypeptide-based block copolymer micelles are deposited onto the surfaces of PCL/Coll nanofibers using tannic acid as a binding partner. Micelle-modified fibrous scaffolds are favorable for wound healing, not only supporting the attachment and spreading of fibroblasts comparable to those on noncoated nanofibers, but also significantly enhancing fibroblast migration. Micellar coatings can be loaded with gentamicin or clindamycin and exhibit antibacterial activity as measured by Petrifilm and zone of inhibition assays as well as time-dependent reduction of cellular counts of Staphylococcus aureus cultures. Moreover, delivery time of antibiotic dosage is tunable through the application of a novel modular approach. Altogether, this system holds great promise as an infection-mitigating, cell-stimulating, biodegradable skin graft for wound management and tissue engineering., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In orthopedic surgery, osteomyelitis (bone infection) is one of the most serious complications in the last few decades and the resident drug delivery is the key strategy to overcome this issue. Combination of bioactive materials with antibiotics is broadly developed for the handling of osteomyelitis which plays a dual role as bone cell growth and as local drug delivery systems for antibiotic delivery. TiO 2 -SiO 2 mixtures were fabricated on Ti alloy by anodization method. Chitosan-Lysine (CS-LY) biopolymers were coated on composites by electrodeposition method and followed by gentamicin sulfate (GS) which was loaded as a model drug. The layers were characterized by AT-FTIR, XRD, FE-SEM and EDX methods. The mechanical, anticorrosion, antimicrobial effects and biocompatibility of the glazes were considered. In addition, drug loading, continued and prolonged liberation behaviors of GS from the fabricated coating were studied. The apatite development ability and cell viability are outstanding for CS-LY-3 coated composites. In vitro cell experimentations indicate that osteoblasts show good adhesion and high growth rates for CS-LY-3 coated TiO 2 -SiO 2 composite substrate. In conclusion, the surface modification of TiO 2 -SiO 2 /CS-LY-3 coated Ti alloy could be used as a carrier for GS, not only to eradicate the osteomyelitis caused by Gram-negative and Gram-positive bacteria, but also to repair the bone defect initiated by the infection owing to the tunable nanocomposite degradation., (Copyright © 2017. Published by Elsevier Ltd.)

In this paper, we describe a novel, label-free and nicking enzyme-assisted fluorescence signal amplification strategy that demonstrates to be cost efficient, sensitive, and unique for assaying the RNase H activity and inhibition based on G-quadruplex formation using a thioflavin T (ThT) dye. This novel assay method is able to detect RNase H with a detection limit of 0.03 U /mL and further exhibits a good linearity R 2 = 0.9923 at a concentration range of 0.03-1 U/mL under optimized conditions. Moreover, the inhibition effect of gentamycin on the RNase H activity is also studied. This strategy provides a potential tool for the biochemical enzyme analysis and inhibitor screening., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study polymeric blends based on collagen, chitosan and hyaluronic acid in the form of thin films with the addition of gentamicin sulfate were obtained. Surface morphology of films was evaluated based on atomic force microscopy images. Surface free energy was measured and its polar and dispersive components were calculated. Moreover, oxygen and water vapor permeability through the material were measured as well as the water content in materials was studied. Thermal stability was determined by differential scanning calorimetry. Microbiological tests were performed to evaluate the diffusion of the drug from matrixes. The results showed that thin films based on collagen, chitosan and hyaluronic acid enriched in gentamicin sulfate inhibit the growth of both, Gram negative bacteria (E. coli and P. aeruginosa) and Gram positive ones (S. aureus)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The aim of the present study was to develop a novel pH sensitive gelatin methacrylate hydrogel for the controlled delivery of Gentamicin (GS) and Ampicillin (Amp). GS and Amp having synergistic activity is effective in killing multi drug resistant bacteria. The hydrogel was well characterized using FTIR, XRD and SEM techniques. The drug loading and encapsulation efficiency were found to be 85.0 and 77.0% for GS, 79.0 and 88.0% for Amp, respectively. The in vitro swelling, degradation and release profiles suggest the pH dependent behaviour of hydrogel. DPPH Assay confirmed the role of 2-amino guanidine in nullifying the side effect of GS and inhibition percentage of DDLHG is found to be 85.0%. Antimicrobial studies revealed the increased efficiency of the drug combination in killing bacteria., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Sodium alginate (Alg) reacted with antibiotic gentamicin sulfate (GS) in an aqueous-phase condition mediated by carbodiimide chemistry, in the molar ratios Alg: GS of (1:0.5), (1:1) and (1:2). The Alg-GS conjugated derivatives were characterized by elemental analysis for nitrogen content, Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analyses (TGA) and water sorption measurements. XPS and FTIR-ATR analyses clearly indicated that GS molecules covalently attached to the backbone of the alginate chains by amide bond formation. The highest amount of GS bound to Alg (43.5 ± 0.4 wt%) and the highest swelling ratio (4962 ± 661%) were observed for the Alg-GS (1:2) sample. Bioluminescence assays with Pseudomonas aeruginosa PAO1/lecA:lux and colony forming counting of Staphylococcus aureus and Escherichia coli upon contact with all Alg-GS conjugates revealed microbicidal activity; however, Alg-GS (1:2) was the most efficient, due to the highest GS content., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Conventional local treatment for medullary osteomyelitis (OM) includes insertion of antibiotic-loaded polymethylmethacrylate (PMMA) cement. Nevertheless, PMMA may delivery irregular concentration of antibiotic to surrounding tissue. We aimed to compare the in vitro antibacterial activity of Bioactive Glass (BAG) S53P4, which is a compound showing local antibacterial activity, to that of antibiotic-loaded PMMA against multidrug resistant bacteria from OM isolates., Methods: We studied convenience samples of multidrug resistant (MDR) microorganisms obtained from patients presenting OM and prosthetic joint infection (PJI). Mixtures containing tryptic soy broth (TSB) and inert glass beads (2 mm), BAG-S53P4 granules (0.5-0.8 mm and < 45 mm) and Gentamicin or Vancomycin-loaded PMMA beads were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CoNS), Pseudomonas aeruginosa or Klebsiella pneumoniae isolates. Glass beads (2.0 mm) were used as a control. Antibacterial activity was evaluated by means of time-kill curve, through seeding the strains on blood agar plates, and subsequently performing colony counts after 24, 48, 72, 96, 120 and 168 h of incubation. Differences between groups were evaluated by means of two-way analysis of variance (ANOVA) and Bonferroni's t test., Results: Inhibition of bacterial growth started soon after 48 h of incubation, reached zero CFU/ml between 120 and 168 h of incubation for both antibiotic-loaded PMMA and BAG S53P4 groups, in comparison with inert glass (p < 0.05). No difference regarding time-kill curves between antibiotic-loaded PMMA and BAG S53P4 was observed., Conclusions: BAG S53P4 presented antibacterial properties as much as antibiotic-loaded PMMA for MDR bacteria producing OM and PJI.

A facile one-step sonochemical method was employed for the first time for gentamicin nanoparticles (GNPs) fabrication and embedding into the surface of parylene C implant coating. The developed system was thoroughly characterized in terms of particle size (NTA, STEM/EDX), surface dispersion (IR-image) and drug release kinetics (UV-Vis). It was revealed that the optimization of the applied ultrasound conditions resulted in the formation of GNPs with an average size in the narrow range of 30-70 nm and their docking into the parylene C nanopores, while the molecular structure of the antibiotic was preserved as confirmed by the FTIR spectra. The obtained surface morphology resulted in controlled elution of the drug up to 7 days, and the kinetics followed the Korsmeyer-Peppas model. The apparent benefits of the proposed sonochemical approach (short preparation time, direct drug accessibility, lack of chemical wastes) are pointed out., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Bacterial infections and biofilm formation on the surface of implants are important issues that greatly affect biomedical applications and even cause device failure. Construction of high drug loading systems on the surface and control of drug release on-demand is an efficient way to lower the development of resistant bacteria and biofilm formation. In the present study, (montmorillonite/hyaluronic acid-gentamicin) 10 ((MMT/HA-GS) 10 ) organic/inorganic hybrid multilayer films were alternately self-assembled on substrates. The loading dosage of GS was as high as 0.85 mg/cm 2 , which could be due the high specific surface area of MMT. The obtained multilayer film with high roughness gradually degraded in hyaluronidase (HAS) solutions or a bacterial infection microenvironment, which caused the responsive release of GS. The release of GS showed dual enzyme and bacterial infection responsiveness, which also indicated good drug retention and on-demand self-defense release properties of the multilayer films. Moreover, the GS release responsiveness to E. coli showed higher sensitivity than that to S. aureus. There was only ∼5 wt % GS release from the film in PBS after 48 h of immersion, and the amount quickly increased to 30 wt % in 10 5 CFU/mL of E. coli. Importantly, the high drug dosage, smart drug release, and film peeling from the surface contributed to the efficient antibacterial properties and long-term biofilm inhibition functions. Both in vitro and in vivo antibacterial tests indicated efficient sterilization function and good mammalian cell and tissue compatibility.

Patients with inadequate volume of alveolar processes or bone defects commonly require graft substitutes in oral, maxillofacial or orthopedic surgery. Ridge augmentation and reconstruction of facial bony defects with bone graft materials achieve better outcomes in functional and aesthetic rehabilitation. The injectable calcium sulfate filler is used widely in intra-operative applications. Calcium sulfate bone filler has been shown to upregulate bone formation-related mRNA genes in vitro and improve osseointegration in vivo. In addition, the bone graft substitute can be used as a drug delivery system for antibiotics to treat or prevent infections based on the clinical experiences. However, the influences of antibiotics addition on the calcium sulfate are not fully understood. In this study, calcium sulfate impregnated with gentamycin in different weight ratios was characterized. The results showed that gentamycin prolonged the hydration process and extended initial/final setting times of calcium sulfate. The addition of gentamycin slowed the conversion from calcium sulfate hemihydrate to dihydrate and changed the crystalline phase and microstructure. Higher amounts of gentamycin added resulted in faster degradation and lower mechanical strength of calcium sulfate. This study reveals that the extended setting time, decreased compressive strength, and the accelerated degradation of the gentamycin-impregnated calcium sulfate bone graft substitutes should be considered during intra-operative applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 80-87, 2018., (© 2016 Wiley Periodicals, Inc.)

Bone and implant-associated infections caused by microorganisms that grow in biofilms are difficult to treat because of persistence and recurrence of infection. Along with surgical debridement, the combination of systemic and local administration of antimicrobials represents the background for an efficient treatment strategy. Gentamicin is one of most used antibiotics for the local treatment of bone-related infections, alone or in combination, due to its bactericidal and broad-range activity. Gentamicin-loaded beads (GLBs), composed of calcium sulfate/hydroxyapatite, were assessed for their in vitro antimicrobial activity against planktonic and biofilm S. agalactiae, S. aureus, S. epidermidis, E. faecalis and E. coli, using standard methods and ultra-sensitive isothermal microcalorimetry. Gentamicin released from GLBs to clinically relevant concentrations (200-2500μg/mL) within 1h was able to kill planktonic S. agalactiae, S. epidermidis and E. coli at lower concentrations (MIC: ≤4μg/mL). Moreover, 12 and 23μg/mL of released gentamicin were able to prevent bacterial adhesion and suppress a 24h-old biofilm of E. coli, respectively. Conversely, higher amounts of antibiotic, ranging from 171 to 1260μg/mL, were needed to prevent and eradicate biofilms of gram-positive bacteria. Likewise, the emergence of resistance to GLBs in vitro and the bacterial attachment on the bone graft substitute, when the amount of gentamicin in the material is reduced, were also reported. This study provides further information regarding the in vitro anti-biofilm activity of the biphasic gentamicin-loaded bone graft substitute, suggesting the validity of this antibiotic-loaded material for the prophylaxis and treatment of bone and implant-associated infections., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The aminoglycoside resistance conferred by an N1-methylation of A1408 in 16S rRNA by a novel plasmid-mediated methyltransferase NpmA can be a future health threat. In the present study, we have determined crystal structures of the bacterial ribosomal decoding A site with an A1408m1A antibiotic-resistance mutation both in the presence and absence of aminoglycosides. G418 and paromomycin both possessing a 6'-OH group specifically bind to the mutant A site and disturb its function as a molecular switch in the decoding process. On the other hand, binding of gentamicin with a 6'-NH3+ group to the mutant A site could not be observed in the present crystal structure. These observations agree with the minimum inhibitory concentration of aminoglycosides against Escherichia coli. In addition, one of our crystal structures suggests a possible conformational change of A1408 during the N1-methylation reaction by NpmA. The structural information obtained explains how bacteria acquire resistance against aminoglycosides along with a minimum of fitness cost by the N1-methylation of A1408 and provides novel information for designing the next-generation aminoglycoside., (© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.)

In addition to customizing shapes of metal bone substitutes for patients, the 3D printing technique can reduce the modulus of the substitutes through the design and manufacture of interconnected porous structures, achieving the modulus match between substitute and surrounding bone to improve implant longevity. However, the porous bone substitutes take more risks of postoperative infection due to its much larger surface area compared with the traditional casting solid bone substitute. Here, we prepared of gentamicin-loaded silk fibroin coatings on 3D-printed porous cobalt-chromium-molybdenum (CoCrMo) bone substitutes via electrophoretic deposition technique. Through optimization, relatively intact, continuous, homogeneous, and conformal coatings with a thickness of 2.30 ± 0.58 μm were deposited around the struts with few pore blocked. The porous metal structures exhibited no loss in mechanical properties after the anode galvanic corrosion in EPD process. The initial osteoblastic response on coatings was better than that on metal surface, including cell spreading, proliferation and cytotoxicity. Antibacterial efficacy experiments showed that the coatings had an antibacterial effect on both adherent and planktonic bacteria within 1 week. These results suggested that the beneficial properties of anode electrophoretic deposited silk fibroin coatings could be exploited to improve the biological functionality of porous structures made of medical metals.

Neonatal infections are a leading cause of childhood mortality in low-resource settings. World Health Organization guidelines for outpatient treatment of possible serious bacterial infection (PSBI) in neonates and young infants when referral for hospital treatment is not feasible include intramuscular gentamicin (GEN) and oral amoxicillin. GEN is supplied as an aqueous solution of gentamicin sulphate in vials or ampoules and requires health care workers to be trained in dose calculation or selection of an appropriate dose based on the patient's weight band and to have access to safe injection supplies and appropriate sharps disposal. A simplified formulation, packaging, and delivery method to treat PSBI in low-resource settings could decrease user error and expand access to lifesaving outpatient antibiotic treatment for infants with severe infection during the neonatal period. We developed dissolving polymeric microneedles (MN) arrays to deliver GEN transdermally. MN arrays were produced from aqueous blends containing 30% (w/w) of GEN and two polymers approved by the US Food and Drug Administration: sodium hyaluronate and poly(vinylpyrrolidone). The arrays (19×19 needles and 500μm height) were mechanically strong and were able to penetrate a skin simulant to a depth of 378μm. The MN arrays were tested in vitro using a Franz Cell setup delivering approximately 4.45mg of GEN over 6h. Finally, three different doses (low, medium, and high) of GEN delivered by MN arrays were tested in an animal model. Maximum plasma levels of GEN were dose-dependent and ranged between 2 and 5μg/mL. The time required to reach these levels post-MN array application ranged between 1 and 6h. This work demonstrated the potential of dissolving MN arrays to deliver GEN transdermally at therapeutic levels in vivo., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: To develop polysaccharide-based membranes that allow controlled and localized delivery of gentamicin for the treatment of post-operative bone infections., Methods: Membranes made of gellan gum (GUM), sodium alginate (ALG), GUM and ALG crosslinked with calcium ions (GUM + Ca and ALG + Ca, respectively) as well as reference collagen (COL) were produced by freeze-drying. Mechanical properties, drug release, antimicrobial activity and cytocompatibility of the membranes were assessed., Results: The most appropriate handling and mechanical properties (Young's modulus, E = 92 ± 4 MPa and breaking force, F MAX  = 2.6 ± 0.1 N) had GUM + Ca membrane. In contrast, COL membrane showed F MAX  = 0.14 ± 0.02 N, E = 1.0 ± 0.3 MPa and was deemed to be unsuitable for antibiotic delivery. The pharmacokinetic data demonstrated a uniform and sustainable delivery of gentamicin from GUM + Ca (44.4 ± 1.3% within 3 weeks), while for COL, ALG and ALG + Ca membranes the most of the drug was released within 24 h (55.3 ± 1.9%, 52.5 ± 1.5% and 37.5 ± 1.8%, respectively). Antimicrobial activity against S. aureus and S. epidermidis was confirmed for all the membranes. GUM + Ca and COL membranes supported osteoblasts growth, whereas on ALG and ALG + Ca membranes cell growth was reduced., Conclusions: GUM + Ca membrane holds promise for effective treatment of bone infections thanks to favorable pharmacokinetics, bactericidal activity, cytocompatibility and good mechanical properties.

We investigated the efficacy of liposomal gentamicin formulations of different surface charges against Pseudomonas aeruginosa and Klebsiella oxytoca . The liposomal gentamicin formulations were prepared by the dehydration-rehydration method, and their sizes and zeta potential were measured. Gentamicin encapsulation efficiency inside the liposomal formulations was determined by microbiologic assay, and stability of the formulations in biologic fluid was evaluated for a period of 48 h. The minimum inhibitory concentration and the minimum bactericidal concentration were determined, and the in vitro time kill studies of the free form of gentamicin and liposomal gentamicin formulations were performed. The activities of liposomal gentamicin in preventing and reducing biofilm-forming P. aeruginosa and K. oxytoca were compared to those of free antibiotic. The sizes of the liposomal formulations ranged from 625 to 806.6 nm in diameter, with the zeta potential ranging from -0.22 to -31.7 mV. Gentamicin encapsulation efficiency inside the liposomal formulation ranged from 1.8% to 43.6%. The liposomes retained >60% of their gentamicin content during the 48 h time period. The minimum inhibitory concentration of neutral formulation was lower than that of free gentamicin (0.25 versus 1 mg/L for P. aeruginosa and 0.5 versus 1 mg/L for K. oxytoca ). The negatively charged formulation exhibited the same bacteriostatic concentration as that of free gentamicin. The minimum bactericidal concentration of neutral liposomes on planktonic bacterial culture was twofold lower than that of free gentamicin, whereas the negatively charged formulations were comparable to free gentamicin. The killing time curve values for the neutral negatively charged formulation against planktonic P. aeruginosa and K. oxytoca were better than those of free gentamicin. Furthermore, liposomal formulations prevent the biofilm-formation ability of these strains better than free gentamicin. In summary, liposomal formulations could be an effective lipid nanoparticle to combat acute infections where planktonic bacteria are predominant., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Simultaneous determination of miconazole (MIC), mometasone furaoate (MF), and gentamicin (GEN) in their pharmaceutical combination. Gentamicin determination is based on derivatization with of o-phthalaldehyde reagent (OPA) without any interference of other cited drugs, while the spectra of MIC and MF are resolved using both successive and progressive resolution techniques. The first derivative spectrum of MF is measured using constant multiplication or spectrum subtraction, while its recovered zero order spectrum is obtained using derivative transformation. Beside the application of constant value method. Zero order spectrum of MIC is obtained by derivative transformation after getting its first derivative spectrum by derivative subtraction method. The novel method namely, differential amplitude modulation is used to get the concentration of MF and MIC, while the novel graphical method namely, concentration value is used to get the concentration of MIC, MF, and GEN. Accuracy and precision testing of the developed methods show good results. Specificity of the methods is ensured and is successfully applied for the analysis of pharmaceutical formulation of the three drugs in combination. ICH guidelines are used for validation of the proposed methods. Statistical data are calculated, and the results are satisfactory revealing no significant difference regarding accuracy and precision., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A pyridinium-amphiphile-loaded poly(lactic-co-glycolic acid) (PLGA) nanocarrier (C1-PNC) was developed as an adjuvant in order to break the resistance and restore the susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) cells to therapeutic antibiotics. Notably, against a clinical MRSA strain, C1-PNC was found to render 8- and 6-fold decreases in the minimum biofilm eradication concentration (MBEC 90 ) of gentamicin and ciprofloxacin, respectively. Mechanistic studies on MRSA planktonic cells revealed that in the case of gentamicin, C1-PNC promotes enhanced cellular uptake of the antibiotic, whereas the propensity of C1-PNC to inhibit efflux pump activity could be leveraged to enhance cellular accumulation of ciprofloxacin, leading to effective killing of MRSA cells. Interestingly, the combinatorial dosing regimen of C1-PNC and the antibiotics was nontoxic to cultured HEK293 cells. This nontoxic amphiphile-loaded nanomaterial holds considerable promise as an adjuvant for antibiotic-mediated alleviation of MRSA biofilms., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Antibiotic loaded bone cements are used as drug delivery systems for the treatment of periprosthetic joint infections. They can be loaded with antibiotics during industrial component production (premixing) and during cement preparation (manually blending). Although double premixed antibiotic loaded bone cements are available, manually blending of a gentamicin premixed antibiotic loaded bone cement with vancomycin is still popular. We compared in vitro antibiotic elution and compressive strength of 0.5 g gentamicin premixed bone cement (PALACOS® R + G), 0.5 g gentamicin premixed bone cement (PALACOS® R + G) manually blended with 2.0 g vancomycin, 0.5 g gentamicin and 2.0 g vancomycin premixed bone cement (COPAL® G + V), 1 g gentamicin and clindamycin premixed bone cement (COPAL® G + C) and bone cement without an antibiotic (PALACOS® R) as control. Antibiotic concentration measurements were performed for 6 weeks and then compression strength was tested. Concentrations of gentamicin showed no significant differences between PALACOS® R + G, PALACOS® R + G with vancomycin and COPAL G® + V. After 48 h COPAL G® + C produced significantly higher gentamicin concentrations than the other formulations. After 12 h PALACOS® R + G with vancomycin produced significantly higher vancomycin concentrations, but had the lowest compression strength. We found no influence of vancomycin addition on gentamicin elution, irrespectively of the loading method. However, the manually vancomycin blended ALBC produced higher vancomycin concentrations. Compression strength after aging is reduced by loading with vancomycin.

Kinetic, thermodynamic, and structural properties of the aminoglycoside N3-acetyltransferase-VIa (AAC-VIa) are determined. Among the aminoglycoside N3-acetyltransferases, AAC-VIa has one of the most limited substrate profiles. Kinetic studies showed that only five aminoglycosides are substrates for this enzyme with a range of fourfold difference in k cat values. Larger differences in K M (∼40-fold) resulted in ∼30-fold variation in k cat /K M . Binding of aminoglycosides to AAC-VIa was enthalpically favored and entropically disfavored with a net result of favorable Gibbs energy (ΔG < 0). A net deprotonation of the enzyme, ligand, or both accompanied the formation of binary and ternary complexes. This is opposite of what was observed with several other aminoglycoside N3-acetyltransferases, where ligand binding causes more protonation. The change in heat capacity (ΔCp) was different in H 2 O and D 2 O for the binary enzyme-sisomicin complex but remained the same in both solvents for the ternary enzyme-CoASH-sisomicin complex. Unlike, most other aminoglycoside-modifying enzymes, the values of ΔCp were within the expected range of protein-carbohydrate interactions. Solution behavior of AAC-VIa was also different from the more promiscuous aminoglycoside N3-acetyltransferases and showed a monomer-dimer equilibrium as detected by analytical ultracentrifugation (AUC). Binding of ligands shifted the enzyme to monomeric state. Data also showed that polar interactions were the most dominant factor in dimer formation. Overall, thermodynamics of ligand-protein interactions and differences in protein behavior in solution provide few clues on the limited substrate profile of this enzyme despite its >55% sequence similarity to the highly promiscuous aminoglycoside N3-acetyltransferase. Proteins 2017; 85:1258-1265. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

This paper is focused on preparation and characterization of regenerated muga and tasar fibroin flexible films from cocoon using ionic liquid. These flexible muga and tasar fibroin films were prepared by incorporating dextrose (5 to 15% w/w) as plasticizer. The mechanical, thermal, physical, morphological and biological properties of dextrose plasticized muga and tasar fibroin films were characterized. These plasticized films showed higher elongation at break as well as water holding capacity as compared to the un-plasticized films. The surface roughness and water absorbance capacity of the dextrose plasticized films were higher than un-plasticized films, which results in improved adherence and proliferation of L929 fibroblast cells. Gentamicin loaded plasticized muga and tasar fibroin films showed slightly higher rate of release as compared to un-plasticized films. The biodegradability of dextrose plasticized films was significantly higher as compared to their respective counterpart. The regeneration of flexible muga and tasar silk fibroin films pave the way to expand potential use of non-mulberry in the field of biomedical such as wound dressing., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In the present study, novel heparin-mimetic polyurethane hydrogels were prepared by introducing chemical crosslinked sulfated konjac glucomannan (SKGM). Scanning electron microscopy (SEM) results indicated that the introduction of SKGM and the increase of the molecular weight of diol segments could enlarge the pore sizes of the hydrogels. The swelling behavior corresponded with the SEM results, and the hydrogels could absorb more water after the modification. The modification also led to an improvement in the mechanical property. Meanwhile, the SKGM and the modified polyurethane hydrogels showed excellent hemocompatibility. The thromboplastin time of SKGM could reach up to 182.9s. Gentamycin sulfate (GS) was used as a model drug to be loaded into the hydrogels, and the loading amount was increased ca. 50% after the introduction of SKGM, thus resulting in high bactericidal efficiency. The results indicated that the introduction of SKGM and the alternation in the diol's molecular weight bestowed polyurethane hydrogels with promising properties of integrated blood-compatibility, mechanical properties and drug loading-releasing behavior. Therefore, the heparin-mimetic multifunctional polyurethane hydrogels have great potential to be used in biomedical applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Surgical site infections (SSIs) represent the most common nosocomial infection among surgical patients. In order to prevent SSIs in a sustained manner and lessen side effects, we developed a twisting method for generation of nanofiber-based sutures capable of simultaneous delivery of silver and gentamicin. The prepared sutures are composed of core-sheath nanofibers with gentamicin/pluronic F127 in the core and silver/PCL in the sheath produced by co-axial electrospinning. The diameters of obtained sutures range from ~80 μm to ~1.2 mm. The in vitro release profiles of silver and gentamicin exhibit an initial burst followed by a sustained release over 5 weeks. The co-encapsulated sutures were able to kill bacteria much more effectively than gentamicin or silver alone loaded nanofiber sutures, without showing obvious impact on proliferation and migration of dermal fibroblasts and keratinocytes. The gentamicin and silver co-loaded PCL nanofiber sutures may hold great potential for prevention of SSIs., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Gentamicin modified chitosan film (CS-GT) was produced using a three-step procedure comprising: (i) the chitosan solution was air-dried to form a chitosan (CS) film, (ii) using citric acid to generate the amide and carboxyl groups on the surface of CS, (iii) the CS with surface carboxyl groups was modified by grafting of gentamicin. After modification, this CS-GT film has excellent hydrophilicity and biocompatibility. It is very evident that the gentamicin grafting treatment significantly improves the antibacterial properties of the CS film. Our preliminary results suggest that this novel gentamicin modified chitosan film, which can be prepared in large quantities and at low cost, should have potential application in biomedical applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Although single-drug therapy may prove insufficient in treating bacterial infections or inflammation after orthopaedic surgeries, complex therapy (using both an antibiotic and an anti-inflammatory drug) is thought to address the problem. Among drug delivery systems (DDSs) with prolonged drug release profiles, nanoporous anodic titanium dioxide (ATO) layers on Ti foil are very promising. In the discussed research, ATO samples were synthesized via a three-step anodization process in an ethylene glycol-based electrolyte with fluoride ions. The third step lasted 2, 5 and 10min in order to obtain different thicknesses of nanoporous layers. Annealing the as-prepared amorphous layers at the temperature of 400°C led to obtaining the anatase phase. In this study, water-insoluble ibuprofen and water-soluble gentamicin were used as model drugs. Three different drug loading procedures were applied. The desorption-desorption-diffusion (DDD) model of the drug release was fitted to the experimental data. The effects of crystalline structure, depth of TiO 2 nanopores and loading procedure on the drug release profiles were examined. The duration of the drug release process can be easily altered by changing the drug loading sequence. Water-soluble gentamicin is released for a long period of time if gentamicin is loaded in ATO as the first drug. Additionally, deeper nanopores and anatase phase suppress the initial burst release of drugs. These results confirm that factors such as morphological and crystalline structure of ATO layers, and the procedure of drug loading inside nanopores, allow to alter the drug release performance of nanoporous ATO layers., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Nonsense mutations underlie about 10% of rare genetic disease cases. They introduce a premature termination codon (PTC) and prevent the formation of full-length protein. Pharmaceutical gentamicin, a mixture of several related aminoglycosides, is a frequently used antibiotic in humans that can induce PTC readthrough and suppress nonsense mutations at high concentrations. However, testing of gentamicin in clinical trials has shown that safe doses of this drug produce weak and variable readthrough activity that is insufficient for use as therapy. In this study we show that the major components of pharmaceutical gentamicin lack PTC readthrough activity but the minor component gentamicin B1 (B1) is a potent readthrough inducer. Molecular dynamics simulations reveal the importance of ring I of B1 in establishing a ribosome configuration that permits pairing of a near-cognate complex at a PTC. B1 induced readthrough at all three nonsense codons in cultured cancer cells with TP53 (tumor protein p53) mutations, in cells from patients with nonsense mutations in the TPP1 (tripeptidyl peptidase 1), DMD (dystrophin), SMARCAL1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1), and COL7A1 (collagen type VII alpha 1 chain) genes, and in an in vivo tumor xenograft model. The B1 content of pharmaceutical gentamicin is highly variable and major gentamicins suppress the PTC readthrough activity of B1. Purified B1 provides a consistent and effective source of PTC readthrough activity to study the potential of nonsense suppression for treatment of rare genetic disorders.

Commonly used antimicrobials show poor cellular uptake and often have limited access to intracellular targets, resulting in low antimicrobial activity against intracellular pathogens. An efficient delivery system to transport these drugs to the intracellular site of action is needed. Cell-penetrating peptides (CPPs) mediate the internalization of biologically active molecules into the cytoplasm. Here, we characterized two CPPs, α1H and α2H, derived from the Yersinia enterocolitica YopM effector protein. These CPPs, as well as Tat ( trans -activator of transcription) from HIV-1, were used to deliver the antibiotic gentamicin to target intracellular bacteria. The YopM-derived CPPs penetrated different endothelial and epithelial cells to the same extent as Tat. CPPs were covalently conjugated to gentamicin, and CPP-gentamicin conjugates were used to target infected cells to kill multiple intracellular Gram-negative pathogenic bacteria, including Escherichia coli K1, Salmonella enterica serovar Typhimurium, and Shigella flexneri Taken together, CPPs show great potential as delivery vehicles for antimicrobial agents and may contribute to the generation of new therapeutic tools to treat infectious diseases caused by intracellular pathogens., (Copyright © 2017 American Society for Microbiology.)

The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination with gentamicin were assessed using checkerboard assay and time-kill kinetic study. Results of the present study showed that the combination effects of pterostilbene with gentamicin were synergistic (FIC index < 0.5) against three susceptible bacteria strains: Staphylococcus aureus ATCC 25923 , Escherichia coli O157 and Pseudomonas aeruginosa 15442 . However, the time-kill study showed that the interaction was indifference which did not significantly differ from the gentamicin treatment. Furthermore, time-kill study showed that the growth of the tested bacteria was completely attenuated with 2 to 8 h treatment with 0.5 × MIC of pterostilbene and gentamicin. The identified combinations could be of effective therapeutic value against bacterial infections. These findings have potential implications in delaying the development of bacterial resistance as the antibacterial effect was achieved with the lower concentrations of antibacterial agents.

In this paper, Bi 2 S 3 nanospheres with size of 212nm were prepared by a simple hydrothermal process. The selectively enhanced antibacterial effects of Bi 2 S 3 nanospheres with three classes of ineffective antibiotics, β-lactam (cefuroxime, CXM; cefotaxime, CTX and piperacillin, PIP), quinolone (ciprofloxacin, CIP) and aminoglycoside (gentamicin, GEN) against clinical isolated methicillin-resistant Staphylococcus aureus (MRSA) were investigated for the first time. GEN shows significantly synergistic growth inhibition against MRSA when combined with Bi 2 S 3 nanospheres, while CXM, CTX, PIP and CIP do not. Raman spectroscopy and Z potential studies reveal that Bi 2 S 3 could interact with GEN and the combination showed small electronegativity, which probably induced the increase of GEN content in cytoplasm of bacteria. Furthermore, the combination of Bi 2 S 3 nanospheres and GEN can destroy the bacterial membrane function and induce more bactericidal reactive oxygen generation than that of Bi 2 S 3 or GEN alone. The cytotoxicity test indicates that the combination of Bi 2 S 3 and GEN presented low toxicity to human normal hepatocyte L02. This work shows that Bi 2 S 3 nanospheres can be used to enhance the action of ineffective antibiotic GEN against MRSA, thus strengthening the antibiotic capacity for fighting MRSA infections., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Gentamicin is an antibiotic indicated to treat mastitis in dairy cattle and for the treatment of bacterial resistance in the context of hospital infections. The effect caused by gentamicin on the optical properties of gold nanoparticles aqueous dispersions were used to develop quantitative methods to determine this antibiotic. Two different aqueous dispersions, one containing spherical Au nanoparticles (AuNPs) and the other containing Au nanorods (AuNRs), had their conditions adjusted to enable a stable and sensitive response towards gentamicin. The use of AuNPs, with measurement at 681nm of the rising coupling plasmon band, enabled a limit of detection (LOD) of 0.4ngmL -1 (0.02ng absolute LOD), ten times lower than the one achieved by measuring the decreasing of the longitudinal surface plasmon resonance band (at 662nm). The linear analytical response of AuNPs measured at 681nm did not require rationing of signal values to correct for linearity. Stability of the analytical response resulted in intermediary precision below 2%. No significant interference was imposed by excipients traditionally present in injectable solutions for veterinary use. Percent recoveries obtained in such formulations were between 94.5 and 98.2% regardless the existence of any difference in the proportion of the compounds known as gentamicin (C 1 , C 1a and C 2 ) in standard and in the samples. The method requires no derivatization with toxic reagents as usually is required in other spectroscopic approaches., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: No doubt, the prevention of infection is an indispensable aspect of the wound management, but, simultaneous wound pain relief is also required. Therefore, herein this article, incorporation of antibiotic agent 'gentamicin' and pain relieving agent 'lidocaine' into hydrogel wound dressings, prepared by using acacia gum, carbopol and poly(2-hydroxyethylmethacrylate) polymers, has been carried out. The hydrogels were evaluated as a drug carrier for model drugs gentamicin and lidocaine., Method: Synthesis of hydrogel wound dressing was carried out by free radical polymerization technique. The drug loading was carried out by swelling equilibrium method and gel strength of hydrogels was measured by a texture analyzer., Results: Porous microstructure of the hydrogel was observed in cryo-SEM images. The hydrogel showed mesh size 37.29 nm, cross-link density 2.19× 10-5 mol/cm3, molecular weight between two cross-links 60.25× 10-3 g/mol and gel strength 0.625±0.112 N in simulated wound fluid., Conclusion: It is concluded that the pH of swelling medium has influenced the network structure of hydrogel i.e., molecular weight of the polymer chain between two neighboring cross links, crosslink density and the corresponding mesh size. A good correlation was established between gel strength and network parameters. Cryo-SEM images showed porous morphology of hydrogels. These hydrogels were found to be biodegradable and antimicrobial in nature. Drug release occurred through Fickian diffusion mechanism and release profile was best fitted in first order model. Overall it is concluded that modification in GA has led to formation of a porous hydrogels for wound dressing applications., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Aims: Vancomycin is commonly added to acrylic bone cement during revision arthroplasty surgery. Proprietary cement preparations containing vancomycin are available, but are significantly more expensive. We investigated whether the elution of antibiotic from 'home-made' cement containing vancomycin was comparable with more expensive commercially available vancomycin impregnated cement., Materials and Methods: A total of 18 cement discs containing either proprietary CopalG+V; or 'home-made' CopalR+G with vancomycin added by hand, were made. Each disc contained the same amount of antibiotic (0.5 g gentamycin, 2 g vancomycin) and was immersed in ammonium acetate buffer in a sealed container. Fluid from each container was sampled at eight time points over a two-week period. The concentrations of gentamicin and vancomycin in the fluid were analysed using high performance liquid chromatography mass spectrometry., Results: The highest peak concentrations of antibiotic were observed from the 'home-made' cements containing vancomycin, added as in the operating theatre. The overall elution of antibiotic was, fivefold (vancomycin) and twofold (gentamicin) greater from the 'home-made' mix compared with the commercially mixed cement. The use of a vacuum during mixing had no significant effect on antibiotic elution in any of the samples., Conclusion: These findings suggest that the addition of 2 g vancomycin powder to gentamicin-impregnated bone cement by hand significantly increases the elution of both antibiotics compared with commercially prepared cements containing vancomycin. We found no significant advantages of using expensive commercially produced vancomycin-impregnated cement and recommend the addition of vancomycin powder by hand in the operating theatre. Cite this article: Bone Joint J 2017;99-B:73-7., (©2017 The British Editorial Society of Bone & Joint Surgery.)

Knowledge about the elution from antibiotic-loaded cement spacers is an indispensable premise for guarantee of clinical success. A systematic literature search was performed through PubMed. Search terms were "antibiotic elution" and "antibiotic release" in combination with "spacer," "hip spacer," and "knee spacer," respectively. A total of 11 studies could be identified. Seven studies reported on the release of antibiotics after spacer implantation, three studies at spacer removal, and one study on both time points. Seven studies reported on hip spacers, one study on knee spacers, and three studies on both. In eight studies, custom-made spacers have been implanted and in three prefabricated ones. In the majority of the studies, the cement has been loaded with an antibiotic combination, mostly consisting of aminoglycoside (either gentamicin or tobramycin) and vancomycin. Measured concentrations exceeded the minimal inhibitory concentration of the particular pathogen organisms in each case. However, large discrepancies were observed with regard to the height of the antibiotic concentration depending on the antibiotic combination and the antibiotic ratio used. Current literature data indicate a sufficient elution of antibiotics after spacer implantation and at spacer removal, respectively. Future studies are required to optimize the local antibiotic therapy at the site of spacer implantation.

Our aim was to develop a biocompatible bone repair material that has the advantage of preventing postoperative infections. Finally, the porous magnesium (p-Mg) loaded with gentamicin sulphate (GS-loaded Mg-G) was fabricated. The GS release behavior of the GS-loaded Mg-G in phosphate buffer saline (PBS) was investigated. The effective release time of GS reached to 14days. In addition, the effects of porosity and pore diameter of p-Mg on the GS release behavior of the GS-loaded Mg-G were studied. In the initial burst release stage, the GS release rate of the GS-loaded Mg-G increased with the increasing porosity or the increasing pore diameter of p-Mg. The GS-loaded Mg-G with larger original pore diameter has higher burst release of GS. Moreover, the in vitro antibacterial test of the GS-loaded Mg-G indicated that this biomaterial has obvious antibacterial effect. This study can provide information for p-Mg loaded with drug(s) as functional bone repair materials with drug-delivery capabilities., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Microspheres with hollow and/or porous structures have been widely used in various applications. A new method of spraying and freezing emulsions was developed to prepare hollow HA (hydroxyapatite) microspheres with interconnected pores by using PVA (polyvinyl alcohol) as emulsifiers and binders. The relationships between viscosity and shear time or rates were tested and the dispersing stability of oil in water (O/W) emulsions was characterized with comparison to suspensions without the addition of oil phase. The effects of solid loadings of HA and the volume ratio between oil and water on the morphologies of microspheres were investigated. Hollow HA microspheres with particle diameter of ~20μm and pore size of ~0.6μm were successfully obtained by spray freezing method. Besides, drying and sintering processes were crucial to the formation of hollow and porous structures, respectively. The gentamicin loading and releasing of HA porous microspheres with different hollow volumes were tested., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Electrospinning is an emerging technique used for fabrication of nanofibrous mats for skin tissue engineering applications. The aim of this study centered on fabrication of muga fibroin electrospun mats by using ionic liquid and its characterizations. The muga fibroin extracted from cocoon of Antheraea assama is dissolved in 1-butyl, 3-methyl imidazolium acetate (BMIMAc), a green solvent, to prepare a dope solution for electrospinning. The molecular weight, rheology and structural properties of dope solution are characterized. The process parameters of electrospinning machine such as voltage and concentration of dope solution are varied to obtain nanofibrous mats. The nanofibrous mat having average fiber diameter of 160nm are obtained from 10% w/v concentration of muga fibroin in BMIMAc with an applied voltage of 20KV. The mechanical, structural, physical and thermal properties of muga nanofibrous mat (MNF) are analyzed and compare with muga cast film. The cytocompatibility test is performed using L929 fibroblast cells. It is observed that muga nanofibrous mat support higher growth of fibroblast cells (p<0.05) as compared to muga cast film (MCF). Muga nanofibrous mat and cast film are loaded with gentamycin sulphate. The release rate and antimicrobial efficiency of gentamycin sulphate loaded muga nanofibrous mat are found to be significantly higher (p<0.05) as compared to muga cast film. All these results indicate that muga nanofibrous mat would be a promising material for skin tissue engineering., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objectives: Numerous studies have examined the biomechanics of polymethyl methacrylate (PMMA) with added antibiotics, but direct comparison between studies is difficult. Our purpose was to evaluate the effects of the addition of antibiotic drugs and silver on compressive and bending strength of PMMA. Our null hypothesis was that there would be no significant difference in the compressive strength or bending strength of PMMA with the addition of silver or varying amounts of antibiotic drugs., Methods: Polymethyl methacrylate was mixed with cefazolin, gentamicin, vancomycin, or silver; the control was PMMA alone. Antibiotic groups contained 20 g PMMA and 0.5 g, 1 g, 2 g, or 3 g of antibiotic. Silver groups had 0.25 g silver powder alone added to 20 g PMMA or silver with PMMA and 0, 0.5 g or 1 g of antibiotic. Samples underwent four-point bending and compression testing in air at room temperature and prevailing humidity. Pairwise comparisons between groups and to the ASTM and ISO standards were performed., Results: Compression: All antibiotic and silver groups were weaker than the control. Samples with cefazolin tended to be stronger than other antibiotic groups with equivalent doses of antibiotic. All groups were above the ASTM standard, except 3 g vancomycin. Four-point bending: The addition of antibiotics did not significantly affect bending strength in groups with lower doses of antibiotics. The silver + PMMA group was weaker than the control. No groups were significantly below the ISO standard except the 3 g vancomycin group., Clinical Significance: The addition of antibiotic or silver decreased the biomechanical strength in all samples, but not below the ASTM or ISO standard for most groups. The addition of cefazolin appears to affect strength the least, while high doses of vancomycin alter strength the most.

This study was designed to determine the degree and type of bacterial contamination in boar semen (79 ejaculates from Large White and Landrace boars) and its consequences for sperm quality during storage (27 extended semen samples, 16°C for five days) under practical conditions of artificial insemination (AI). The results revealed the presence of aerobic bacteria in 99% of the ejaculates (from 80 to 370 ×106 colony-forming units/mL). Most of the ejaculates contained two or three bacterial contaminants, while the Staphylococcus, Streptococcus, and Pseudomonas bacterial genera were most frequently isolated. Also detected were Enterobacter spp., Bacillus spp., Proteus spp., Escherichia coli, P. fluorescens, and P. aeruginosa. In general, the growth of certain bacterial types isolated prior to semen processing (Enterobacter spp., E. coli, P. fluorescens, and P. aeruginosa) was not discovered on different days of storage, but fluctuations (with a tendency towards increases) were found in the frequencies of Bacillus spp., Pseudomonas spp., and Staphylococcus spp. isolates up to the end of storage. Semen preserved for five days exhibited decreases in sperm motility and increases in the average number of total aerobic bacteria; this was associated with sperm agglutination, plasma membrane disruption, and acrosome damage. We inferred that, due to the different degrees and types of bacterial contaminants in the boar ejaculates, the inhibitory activity of some antimicrobial agents used in swine extenders (such as gentamicin sulfate) may be limited. Because such agents can contribute to the overgrowth of certain aerobic bacteria and a reduction in the quality of stored semen, procedures with high standards of hygiene and microbiological control should be used when processing boar semen.

The aim of this research was to prepare and optimize calcium carbonate (CaCO3) nanoparticles as carriers for gentamicin sulfate. A chemical precipitation method was used to prepare the gentamicin sulfate-loaded CaCO3 nanoparticles. A 3-factor, 3-level Box-Behnken design was used for the optimization procedure, with the molar ratio of CaCl2: Na2CO3 (X1), the concentration of drug (X2), and the speed of homogenization (X3) as the independent variables. The particle size and entrapment efficiency were considered as response variables. Mathematical equations and response surface plots were used, along with the counter plots, to relate the dependent and independent variables. The results indicated that the speed of homogenization was the main variable contributing to particle size and entrapment efficiency. The combined effect of all three independent variables was also evaluated. Using the response optimization design, the optimized Xl-X3 levels were predicted. An optimized formulation was then prepared according to these levels, resulting in a particle size of 80.23 nm and an entrapment efficiency of 30.80%. It was concluded that the chemical precipitation technique, together with the Box-Behnken experimental design methodology, could be successfully used to optimize the formulation of drug-incorporated calcium carbonate nanoparticles.

In this study, pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles samples were prepared by precipitation and co-precipitation methods. These nanoparticles were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), Dynamic light scattering (DLS), UV-visible and photoluminescence (PL) spectroscopy. The synthesized pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles have smart optical properties and average sizes with 3.2, 3.12, 3.08 and 2.97eV of band-gap, 18.1, 23.2, 25.7 and 30.2nm, respectively. Photocatalytic activity of four nanoparticles was studying towards degradation of gentamicin antibiotic under ultraviolet and visible light irradiation. The result showed that Zn,Cu co-doped WO3 possessed high photocatalytic activity. The photocatalytic activity of WO3 nanoparticles could be remarkably increased by doping the Zn and Cu impurity. This can be attributed to the fact that the red shift of absorption edge and the trapping effect of the mono and co-doped WO3 nanoparticles. The research result presents a general and effective way to prepare different photocatalysts with enhanced visible and UV light-driven photocatalytic performance. Antibacterial activity of four different WO3 nanoparticles against Escherichia coli bacterium has been assessed by the agar disc method under light irradiation and dark medium. It is concluded from the present findings that WO3 nanoparticles can be used as an efficient antibacterial agent., (Copyright © 2016 Elsevier B.V. All rights reserved.)