Design of an antibacterial gelatin based on a covalent protein-protein coupling

A grafting approach for nisin-chitosan bio-based antibacterial films: preparation and characterization

Nisin is a bacteriocin produced by Gram-positive lactic acid bacterium,Lactococcus lactisand currently recognized in the Generally Recognızed as Safe (GRAS) category due to its non-toxicity. Herein, nisin has been grafted to chitosan structure to obtain natural bio-active films with enhanced antibacterial activity. Grafting was performed using ethyl ester lysine diisocyanate and dimer fatty acid-based diisocyanate (DDI); two different close to fully bio-based diisocyanates and Disuccinimidyl suberate; a homo-bifunctional molecule acting as a crosslinker between amino groups. The grafting process allowed the chemical immobilization of nisin to chitosan structure. Physicochemical characterization studies showed the successful grafting of nisin. The antibacterial activity againstStaphylococcus aureuswas evident for all nisin modified chitosan films and best pronounced when DDI was used as a crosslinker with a maximum zone of inhibition of ∼13 mm. All nisin grafted chitosan films were cytocompatible and the cell viability of L929 fibroblasts were >80% pointing out the non-toxic structure. Considering the results of the presented study, bio-based diisocyanates and homo-bifunctional crosslinkers are effective molecules in synthesis of nisin grafted chitosan structures and the new chitosan based antibacterial biopolymers obtained after nisin modification come forward as promising non-toxic and bioactive candidates to be applied in medical devices, implants, and various food coating products.

Synthesis and evaluation of alendronate-modified gelatin biopolymer as a novel osteotropic nanocarrier for gene therapy

AIM

To synthesize an osteotropic alendronate functionalized gelatin (ALN-gelatin) biopolymer for nanoparticle preparation and targeted delivery of DNA to osteoblasts for gene therapy applications.

MATERIALS & METHODS

Alendronate coupling to gelatin was confirmed using Fourier transform IR, (31)PNMR, x-ray diffraction (XRD) and differential scanning calorimetry. ALN-gelatin biopolymers prepared at various alendronate/gelatin ratios were utilized to prepare nanoparticles and were optimized in combination with DNA and gemini surfactant for transfecting both HEK-293 and MG-63 cell lines.

RESULTS

Gelatin functionalization was confirmed using the above methods. Uniform nanoparticles were obtained from a nanoprecipitation technique. ALN-gelatin/gemini/DNA complexes exhibited higher transfection efficiency in MG-63 osteosarcoma cell line compared with the positive control.

CONCLUSION

ALN-gelatin is a promising biopolymer for bone targeting of either small molecules or gene therapy applications.