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Magnetic hybrid hydrogels have exhibited remarkable efficacy in various areas, particularly in the biomedical sciences, where these inventive substances exhibit intriguing prospects for controlled drug delivery, tissue engineering, magnetic separation, MRI contrast agents, hyperthermia, and thermal ablation. Additionally, droplet-based microfluidic technology enables the fabrication of microgels possessing monodisperse characteristics and controlled morphological shapes. Here, alginate microgels containing citrated magnetic nanoparticles (MNPs) were produced by a microfluidic flow-focusing system. Superparamagnetic magnetite nanoparticles with an average size of 29.1 ± 2.5 nm and saturation magnetization of 66.92 emu/g were synthesized via the co-precipitation method. The hydrodynamic size of MNPs was changed from 142 nm to 826.7 nm after the citrate group’s attachment led to an increase in dispersion and the stability of the aqueous phase. A microfluidic flow-focusing chip was designed, and the mold was 3D printed by stereo lithographic technology. Depending on inlet fluid rates, monodisperse and polydisperse microgels in the range of 20–120 μm were produced. Different conditions of droplet generation in the microfluidic device (break-up) were discussed considering the model of rate-of-flow-controlled-breakup (squeezing). Practically, this study indicates guidelines for generating droplets with a predetermined size and polydispersity from liquids with well-defined macroscopic properties, utilizing a microfluidic flow-focusing device (MFFD). Fourier transform infrared spectrometer (FT-IR) results indicated a chemical attachment of citrate groups on MNPs and the existence of MNPs in the hydrogels. Magnetic hydrogel proliferation assay after 72 h showed a better rate of cell growth in comparison to the control group (p = 0.042).

Methicillin-resistant and Vancomycin-resistant Staphylococcus aureus bacteria (MRSA and VRSA, respectively) can seriously jeopardizes bone implants. This research aimed to examine the potential synergistic effects of Melittin and vancomycin in preventing MRSA and VRSA associated bone implant infections. Chitosan/bioactive glass nanoparticles/vancomycin composites were coated on hydrothermally etched titanium substrates by casting method. The composite coatings were coated by Melittin through drop casting technique. Melittin raised the proliferation of MC3T3 cells, making it an appropriate option as osteoinductive and antibacterial substance in coatings of orthopedic implants. Composite coatings having combined vancomycin and Melittin eliminated both planktonic and adherent MRSA and VRSA bacteria, whereas coatings containing one of them failed to kill the whole VRSA bacteria. Therefore, chitosan/bioactive glass/vancomycin/Melittin coating can be used as a bone implant coating because of its anti-infective properties.

We present a procedure for simultaneous deposition of enzyme-laden chitosan/reduced graphene oxide (rGO) film by electrophoretic deposition (EPD) for fast and efficient detection of glucose. The role of rGO nanosheets is studied on the EPD kinetics of the enzyme-laden suspensions. Investigating the performance of the biosensor by electrochemical techniques indicates its high sensitivity (9700 μA.mM-1.cm-2), low limit of detection (4 µM), and suitable selectivity.

Antibiotics resistant bacteria and biofilm formation on bone implants are the main challenges of present treatment methods in hip or joint replacement surgeries. Recently, antimicrobial peptides (AMPs) have been widely evaluated to degrade resistant bacteria and biofilms. In the present study, chitosan and chitosan/antibiotic were coated on etched titanium specimens by spin coating method and then Melittin thin layer applied on coatings by casting method. Chitosan-Melittin double layer with Melittin higher than 0.2 μg/mL created bactericidal surface and eradicated MRSA bacteria. Melittin, higher than 0.2 μg/mL, showed a toxic effect on MC3T3 pre osteoblast cells. Whereas, coatings with a combination of oxacillin (0.16 μg/mL) and Melittin (0.05 μg/mL) were able to kill MRSA bacteria. Also, coatings with chitosan/vancomycin (0.16 μg/mL)-Melittin (0.05 μg/mL) were able to eradicate VRSA bacteria after 6 h. In conclusion, by the synergistic effect of antibiotics and Melittin, antibiotic-resistant bacterial infections and biofilm formation can be prevented without toxicity.

Multifunctional bone implant coatings are developing for promoting osseointegration and bactericidal efficiency, simultaneously. In present study, chitosan/bioactive glass nanoparticles/vancomycin composite was coated on hydrothermally etched titanium substrate by drop casting method. For prolongation of antibacterial activity during long term, vancomycin was immobilized on bioactive glass nanoparticles, then the modified nanoparticles were deposited with chitosan on hydrothermally etched titanium. SEM, EDS, FT-IR and wettability test were used for materials characterization. The immobilization of vancomycin onto bioactive glass nanoparticles was proved by FT-IR. Release of vancomycin was measured by UV-spectroscopy for up to 14 days. Antibacterial performance against Methicillin Resistance Staphylococcus Aureus (MRSA) strain, both planktonic and in biofilm, was evaluated for up to 14 days. Conjugation of vancomycin revealed a prolonged release profile and bactericidal activity compared to coating without conjugation of the drug. In vitro, coatings with immobilized vancmycin completely eliminated, or reduced the number of planktonic and adherent MRSA by up to 4 and 2 orders of magnitude in initial and later stages, respectively. Vancomycin burst release made a delay in ALP enzyme secretion from MC3T3 cells, while in coating with immobilized vancomycin, the burst release decreased and consequently the delay in ALP enzyme secretion disappeared. The release profile of conjugated vancomycin fitted with Korsmeyer-Peppas model.