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Drug uptake by polymer was modeled using a molecular dynamics (MD) simulation technique. Three drugs--doxorubicin (water soluble), silymarin (sparingly water soluble) and gliclazide (water insoluble)--and six polymers with varied functional groups--alginic acid, sodium alginate, chitosan, Gantrez AN119 (methyl-vinyl-ether-co-malic acid based), Eudragit L100 and Eudragit RSPO (both acrylic acid based)--were selected for the study. The structures were modeled and minimized using molecular mechanics force field (MM+). MD simulation (Gromacs-forcefield, 300 ps, 300 K) of the drug in the vicinity of the polymer molecule in the presence of water molecules was performed, and the interaction energy (IE) between them was calculated. This energy was evaluated with respect to electric-dipole, van der Waals and hydrogen bond forces. A good linear correlation was observed between IE and our own previous data on drug uptake(*) [R² = 0.65, R²adj = 0:65; R²pre = 0:56 and a F ratio of 30.25, P < 0.001; Devarajan et al. (2005) J Biomed Nanotechnol 1:1-9]. Maximum drug uptake by the polymeric nanoparticles (NP) was achieved in water as the solvent environment. Hydrophilic interaction between NP and water was inversely correlated with drug uptake. The MD simulation method provides a reasonable approximation of drug uptake that will be useful in developing polymer-based drug delivery systems.

Ureteral stents find wide application in urology. The majority of patients with indwelling ureteral stents are at an increased risk of urinary tract infection. Stent encrustation and its associated complications lead to significant morbidity. This review critically evaluates various polymers that find their application as ureteral stents with regard to various issues such as encrustation, bacterial colonization, urinary tract infections, and related clinical issues. A complete literature survey was performed, and all the relevant articles were scrutinized thoroughly. We discuss issues of encrustation/biofilm formation, new approaches to their testing, polymers currently available for use, new biomaterials, coatings, and novel ureteral stent designs, thereby providing a complete update on recent advances in the development of stents. Finally, we discuss the future of biomaterial use in the urinary tract.

Two fungal strains isolated from soil and a commercial white-rot fungus, Phanerochaete chrysosporium NCIM 1170 (SF2), were tested for biodegradation of untreated, UV-, and thermal-treated bisphenol A polycarbonate (PC). The isolated strains based on 18S rDNA analysis were characterized as Engyodontium album MTP091 (SF1) and Pencillium spp. MTP093 (SF3). About 5.4% weight loss and 40% reduction in M(n) were observed for UV-treated polycarbonate in one year with SF2 strain. An increase in surface energy and oxygen content and a reduction in methyl index indicated oxidation of PC during this period. PC exposed to the SF1 strain showed a 15 degrees C decrease in glass transition temperature, indicating an increase in the number of chain ends and, hence, an increase in the free volume of polymer. No bisphenol A, the monomer of PC, was detected during the study. NMR and FTIR spectra showed the formation of methyl groups due to pretreatments. EDAX analysis exhibited surface oxidation of the PC. The current study advocates that biodegradation of PC can be enhanced by pretreatments.

Several polymeric materials find application in biomedical implants and devices due to their superior physicochemical properties. The main requirement for these polymers is that they should be biocompatible, which means they prevent bacterial adhesion and are blood compatible. Many parameters contribute to the degree of biocompatibility. This paper discusses the mechanism of the formation of biofilms and lists the factors that influence the bacterial adhesion and haemocompatibility. Polymer surfaces are also modified to enhance adsorption of host cells. The physical, chemical and biological techniques are meant to modify the surface of the biomaterial but at the same time retain the key properties. The various polymer treatment processes have advantages and disadvantages and a few techniques have been proved to be both highly effective at treatment and found suitable for various in vivo environments. The current research focus pertaining to smart materials, biodegradable polymers, combinatorial chemistry, computational modelling and newer analytical techniques to understand polymer-cell interaction holds promise in designing better, cost effective and biocompatible polymers.

Langmuir-Blodgett (LB) films of the water-soluble dye phenosafranine (PS) have been prepared by its adsorption from aqueous dye solution to an arachidic acid (AA) monolayer at the air-water interface. Atomic force microscopy (AFM) images of the LB films revealed the effect of change in pH of deposition on the degree of complexation of AA with the PS dye. Well-defined circular islands and holes were observed which disappeared with the increase in pH. Polarized absorption studies indicated that the dye molecules are oriented uniaxially with their long axis titled at a constant angle to the surface normal of the LB film. Within the restricted geometry of the LB film, the PS dye was electropolymerized to form a two-dimensional film of poly(phenosafranine) sandwiched between arachidic acid layers. The film was characterized by IR spectroscopy, cyclic voltammetry, and AFM. X-ray diffraction studies reveal the presence of a layer structure in the AA-PS LB film before and after polymerization. The polymer film showed highly anisotropic electrical conductivity of ca. 10 orders of magnitude. This indicates the formation of two-dimensional polyPS layers between arachidic acid layers resulting in a layered heterostructure film having alternate conducting and insulating regions. Also, the conductivity of the polyPS prepared from LB film was found to be approximately 2.5 times higher than the conductivity of polyPS prepared by solution polymerization method.

Additive manufacturing (AM) is integrated into almost each industry, with an objective to improve product functionality and decrease costs. Ever since from its introduction four decades ago, AM technologies have used numerous kinds of materials in polymers and composite materials to create complex 3D structures which were almost impossible to manufacture through conventional techniques. However, many concerns remain for widespread applications of 3D-printed materials, which include inhomogeneous distribution of particles, unavailability of spherical particles, poor surface finish, inadequate accuracy, shrinkage in the material, and mismatch in desired mechanical properties. To meet the high standards of part quality, immediate emphasize should be given to these pertaining issues and challenges needs to addressed from the grassroots level. It is understood that, electrospraying, a powder particle production technique, may hold great potential to address these challenges and needs of AM by synthesizing fine spherical particles of any material with high scalability and reproducibility. A comprehensive review has been done to discuss the necessity of electrospraying for AM by providing an extensive summary/insight in current material advances and also attempted to bring the connection between the electrospraying and commercialized AM methods. This article also encourages the readers in obtaining an understanding the leading-edge technology electrospraying and makes them to contribute toward the future generations more effectively. [ABSTRACT FROM AUTHOR]

This study investigated biodegradation of physically pretreated polypropylene (PP) by using two different combinations of microorganisms, namely,Bacillus flexus + Pseudomonas azotoformans(B1) andB. flexus + B. subtilis(B2), for a period of 12 months. The growth rate of (B1) was found to be high throughout the study period, and reached a maximum of 1 × 1014colony-forming units (CFU)/mL. At the end of the experiment, the polymers become hydrophilic. Carbonyl indices showed that ultraviolet (UV)-treated polymers started degrading faster than the thermally treated PP. The thermogravimetric analysis also revealed that UV-treated PP exposed to theB. flexus + P. azotoformanscombination for 1 year exhibited maximum degradation (22.7%). The gravimetric weight loss method showed 1.95% weight loss followed by 1.45% withB. flexus + B. subtilis. The changes in the carbonyl indices of the polymer through Fourier-transform infrared (FTIR) analysis also support the degradation. [ABSTRACT FROM PUBLISHER]

Silver and gold nanoparticles (of average size ∼20–27 nm) were incorporated in PU (Polyurethane), PCLm (Polycaprolactam), PC (polycarbonate) and PMMA (Polymethylmethaacrylate) by swelling and casting methods under ambient conditions. In the latter method the nanoparticle would be present not only on the surface, but also inside the polymer. These nanoparticles were prepared initially by using a cosolvent, THF. PU and PCLm were dissolved and swollen with THF. PC and PMMA were dissolved in CHCl3 and here the cosolvent, THF, acted as an intermediate between water and CHCl3. FTIR indicated that the interaction between the polymer and the nanoparticle was through the functional group in the polymer. The formation of E.coli biofilm on these nanocomposites under low (in a Drip flow biofilm reactor) and high shear (in a Shaker) conditions indicated that the biofilm growth was higher (twice) in the former than in the latter (ratio of shear force = 15). A positive correlation between the contact angle (of the virgin surface) and the number of colonies, carbohydrate and protein attached on it were observed. Ag nanocomposites exhibited better antibiofilm properties than Au. Bacterial attachment was highest on PC and least on PU nanocomposite. Casting method appeared to be better than swelling method in reducing the attachment (by a factor of 2). Composites reduced growth of organisms by six orders of magnitude, and protein and carbohydrate by 2–5 times. This study indicates that these nanocomposites may be suitable for implant applications. [ABSTRACT FROM AUTHOR]

Betanin was immobilized on LDPE by UV cross-linking and tested as food wrapper. The attachment of live Staphylococcus aureu and Escherichia coli bacterial colonies were 2.3 and 1.5 times less respectively on this film when compared to bare polymer. The corresponding reduction in the carbohydrate in the biofilm formed on the surface was 1.6 and 1.9 respectively and that of protein was 2.5 and 2.3 respectively. The modified polymer reduced the growth of S. aureus in cottage cheese and beef by three and four times respectively when wrapped with it for ten days when compared to the food wrapped with unmodified polymer. The phytochemical makes the surface antibacterial, antioxidant and anti-adhesive and can help in extending the shelf life of food. [ABSTRACT FROM AUTHOR]

Developing an effective antibacterial surface with the help of drugs that prevent bacterial adhesion, colonization, and proliferation into the surrounding tissues is of great demand. Rifampicin (Rf) is effective antibiotic drug proved has proved its potential in treating bacteria in biofilms, especially against the microbes causing bone infections. Hydroxyapatite (HA), a biocompatible osteoconductive ceramic, has been verified to be a significant material for bioactivity enhancement. Electrospinning is an effective inexpensive method for incorporating nanoparticles into nanofibers with uniform distribution for the drug delivery system for tissue engineering applications. In the current study, for improving bioactivity and antibacterial properties, novel functional polycaprolactone (PCL) composite nanofibers loaded HA and Rf was developed and coated on titanium (Ti). Different characterization techniques such as SEM, EDS, XRD, FITR were used to analyze these PCL/Rf/HA nanocomposites. The results showed that the bioactivity and tensile strength of the composite scaffold increased with the addition of HA nanoparticles. In vitro bioactivity demonstrated that the PCL/HA/Rf composite nanofibers possess enhanced calcium deposition when compared to the pure sample. Cellular interactive responses such as adhesive and proliferation were evaluated using hFOB human fetal osteoblast cell lines. After 6 days of culturing, the cellular properties on Ti sample coated with PCL/HA/Rf was significantly improved. Antibacterial evaluations on the substrates showed that Rf-loaded PCL/HA fibers displayed >3 log reduction against S. aureus MRSA, and S.epidermidis bacterial strain and >2 log reduction against P.aeruginosa bacteria. In vitro drug release study shows initial burst release of Rf, followed by sustained released of 62% at the end of 32 days. The cell viability, adhesion, and proliferation evaluation suggest that the PCL/HA/Rf coated substrate possess good cytocompatibility. Further incorporation of Rf enhanced the antibacterial property of this nanofibrous scaffold. [ABSTRACT FROM AUTHOR]

Abstract: Effect of biofouling on various polymers and composites such as, Polyurethane (PU), Silicone rubber (SR), Polyester (PET), Glass Fiber Reinforced Polymer (GFRP), Carbon fibre Reinforced Plastic (CFRP) and Syntactic foams (SF) deployed for a period of one year in marine waters at a depth of 1 m was studied. These materials find wide marine applications. SR with lowest surface energy was the least fouled. Maximum barnacle attachment was seen on hard surface (GFRP) and minimum on flexible surface (SR). Attachment of barnacles and polychaetes are positively correlated with surface energy. Fouling load is positively correlated with Surface energy and hardness. The surface energy, hardness and tensile strength reduced while surface roughness considerably increased during this period. Maximum gravimetric weight loss was seen in PET (7.49%) followed by PU (4.25%) and minimum in CFRP (0.45%). Maximum thermogravimetric weight loss was observed in PET (73.5% at 400 °C) followed by PU (71.1%) and least in SR (2.4%). Fourier Transform infrared spectrum revealed that carbonyl/oxidation indices decreased for PET, GFRP, CFRP, and SR indicating biotic degradation. The same index increased for PU indicating abiotic oxidation. [Copyright &y& Elsevier]

Abstract: Unpretreated and Aquaregia, Fenton, thermal and short UV pretreated polypropylene films of 0.05mm thickness were subjected to biodegradation in vitro in minimal medium with four soil cultures, namely Pseudomonas azotoformans, Pseudomonas stutzeri, Bacillus subtilis and Bacillus flexus separately for 12 months. P. azotoformans and B. subtilis are relatively hydrophobic, produce biosurfactant and form biofilm on the polymer with comparatively higher carbohydrate and protein than the other two organisms. All the organisms make use of the polymer as their carbon source. Highest weight loss (2.5%) was observed in the case of short UV treated polymer exposed to B. flexus after one year. The carbonyl indices decreased in one year in the case of pretreated polymer and increased in the case of untreated polymer, indicating only abiotic oxidation in the absence of pretreatment. Increase in surface energy indicated that the polymer became more hydrophilic when compared to the original. P. stutzeri had marginal effect on the polymer. [Copyright &y& Elsevier]

Abstract: Antimicrobial property of chalcone coated high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and polyurethane (PU) against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa is reported here. The presence of chalcone on the surface was confirmed from fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Bacterial adhesion decreased considerably on all the coated surfaces. Bacterial adhesion was highest on PU surface (most hydrophobic) and lowest on HDPE (most hydrophilic) surface. Chalcone seems to damage the membrane of the bacteria as well as exhibit slimicidal activity. Reasonably good correlation was observed between the CFU (Colony Forming Units) ratio (it is defined as the ratio of CFU on coated surface to the chalcone uncoated surface) at the 24th hour against both hydrophobicity of the microorganism and roughness of the coated polymeric surfaces. Increasing roughness of the polymer and hydrophobicity of the microorganisms were positively and negatively correlated respectively with CFU ratio. Hence, the chalcone coated polymers can be used in the development of newer biomaterials. [Copyright &y& Elsevier]

Abstract: Commercial synthetic polymers namely Polycarbonate (PC), Low density polyethylene (LDPE), High density polyethylene (HDPE), and Polypropylene (PP) coupons were immersed for a period of 12 months (Feb 2006 – Feb 2007) in Bay of Bengal, East coast, India. Samples were retrieved every month and the extent of biofouling and biodegradation were monitored. Biofouling was found to depend not only on the season but also on the chemical nature of the polymer. Surface energy of all the four polymers is positively correlated with fouling only at the initial stages (three months) while surface roughness had a negative correlation. The later increased during the study period. Total suspended solids and organic matter were more abundant on HDPE, followed by PP and LDPE, indicating that among polyolefins hydrophobic surfaces (lower surface energy) favor biofouling over one year. Maximum fouling was observed on polycarbonate during initial three months. Chlorophyll a showed a decreasing trend during the study, as secondary foulers such as Balanus amphitrite, were dominant after the monsoon (6th month in the present study). Maximum weight loss was seen in LDPE (1.9%), followed by that in HDPE (1.6%), PC (0.69%) and finally in PP (0.65%) samples in the 12 months time period. FTIR spectra of PC displayed a decrease in carbonate carbonyl index, while an initial increase and a decrease in carbonyl index of polyolefins as a function of time indicated biodegradation. [Copyright &y& Elsevier]