Development of advanced antimicrobial and sterilized plasma polypropylene grafted muga (Antheraea assama) silk as suture biomaterial.

Surface modification of silk fibroin (SF) materials using environmentally friendly and non-hazardous process to tailor them for specific application as biomaterials has drawn a great deal of interest in the field of biomedical research. To further explore this area of research, in this report, polypropylene (PP) grafted muga (Antheraea assama) SF (PP-AASF) suture is developed using plasma treatment and plasma graft polymerization process. For this purpose, AASF is first sterilized in argon (Ar) plasma treatment followed by grafting PP onto its surface. AASF is a non-mulberry variety having superior qualities to mulberry SF and is still unexplored in the context of suture biomaterial. AASF, Ar plasma treated AASF (AASFAr) and PP-AASF are subjected to various characterization techniques for better comparison and the results are attempted to correlate with their observed properties. Excellent mechanical strength, hydrophobicity, antibacterial behavior, and remarkable wound healing activity of PP-AASF over AASF and AASFAr make it a promising candidate for application as sterilized suture biomaterial.

Chitosan coated silk fibroin surface modified by atmospheric dielectric-barrier discharge (DBD) plasma: a mechanically robust drug release system.

The current study is designed to develop mechanically strong chitosan (Cs) coated silk based drug delivery system loaded with amoxicillin trihydrate (AMOX). For this purpose, surface modification of Antherarea assama silk fibroin (AASF) yarn is carried out using dielectric barrier discharge (DBD) oxygen (O2) plasma at atmospheric pressure followed by coating with drug incorporated Cs (AASF/O2/Cs-AMOX). It is observed that O2 plasma treatment results in altering surface chemistry and morphology of silk fibroin surface which subsequently improves mechanical properties of AASF/O2/Cs-AMOX yarn. The AASF/O2/Cs-AMOX yarn exhibits strong antibacterial activities against gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria. In vitro drug release profile reveals biphasic release behavior of AASF/O2/Cs-AMOX yarn consisting of immediate followed by controlled and sustained release of AMOX up to the observation period of 168 hours. MTT cell viability study further reveals that O2 plasma treatment and incorporation of AMOX do not have any adverse effect on cytocompatibility of AASF/O2/Cs-AMOX yarn. Together, all these results suggest that AASF/O2/Cs-AMOX yarn can be explored in treatment of bacterial infected wounds as potential surgical suture.

Surface modification of electrospun PVA/chitosan nanofibers by dielectric barrier discharge plasma at atmospheric pressure and studies of their mechanical properties and biocompatibility.

In this paper, surface of electrospun PVA/Cs nanofibers is modified using dielectric barrier discharge (DBD) plasma and the relationship between the observed mechanical properties and biocompatibility of the nanofibers and plasma-induced surface properties is discussed. Plasma treatment of electrospun PVA/Cs nanofibers is carried out with both inert (argon, Ar) and reactive (oxygen, O2) gases at atmospheric pressure. Incorporation of oxygen-containing polar functional groups on the surface of Ar-plasma treated (PVA/Cs/Ar) and O2-plasma treated (PVA/Cs/O2) nanofibers and increase in surface roughness contribute to the improvement of surface wettability and the decrease of contact angle with water of the nanofibers. Both PVA/Cs/Ar and PVA/Cs/O2 nanofibers show high tensile strength (11.6-15.6%) and Young's modulus (33.8-37.3%) as compared to the untreated one. Experimental results show that in terms of haemolytic activity the PVA/Cs/Ar and PVA/Cs/O2 nanofibers do not cause structural changes of blood cells and meet the biocompatibility requirements for blood-contacting polymeric materials. MTT cell viability results further reveals improvement in biocompatibility of PVA/Cs nanofibers after Ar and O2 plasma treatment. The results suggest that DBD plasma treated electrospun PVA/Cs nanofibers have the potential to be used as wound dressing and scaffolds for tissue engineering.

Penicillin impregnation on oxygen plasma surface functionalized chitosan/Antheraea assama silk fibroin: Studies of antibacterial activity and antithrombogenic property.

Low temperature plasma can effectively tailor the surface properties of natural polymeric biomaterials according to the need for various biomedical applications. Non-mulberry silk, Antheraea assama silk fibroin (AASF) is a natural polymer having excellent biocompatibility and mechanical strength yet unlike mulberry silk, Bombyx mori silk fibroin, has drawn less interest in biomedical research. In the quest for developing as potential biomaterial, surface functionalization of plasma induced chitosan (Cs) grafted AASF ((AASF/O2-CS)g/O2) yarn is carried out using oxygen (O2) plasma. The (AASF/O2-CS)g/O2 yarn exhibits enhanced antithrombogenic property as well as antimicrobial activity against Gram positive (Bacillus subtilis) and Gram negative (Escherichia coli) bacteria as compared to AASF yarn. Moreover, impregnation of antibiotic drug (penicillin G sodium salt, PEN) on (AASF/O2-CS)g/O2 yarn further improves the observed properties. In-vitro hemolysis assay reveals that O2 plasma treatment and subsequent impregnation of PEN do not affect the hemocompatibility of AASF yarn. The present research findings demonstrate that plasma induced grafting of Cs followed by penicillin impregnation could significantly improve the potential applicability of AASF in the field of surgical research.

Controlled antibiotic-releasing Antheraea assama silk fibroin suture for infection prevention and fast wound healing.

BACKGROUND: The quest for developing silk fibroin as a biomaterial for drug release systems continues to draw research interest owing to its impressive mechanical properties as well as biocompatibility and biodegradability. The aim of this study is to develop low-temperature O2 plasma-treated muga (Antheraea assama) silk fibroin (AASF) yarn impregnated with amoxicillin trihydrate as controlled antibiotic-releasing suture (AASF/O2/AMOX) for preventing postoperative site bacterial infection and fast wound healing. METHODS: In this experimental study, AASF and AASF/O2/AMOX sutures are used to close the surgical wounds of adult male Wistar rats of 4 months old and weighing 200-230 g. RESULTS: Surface hydrophilicity induced by O2 plasma results in an increase in drug-impregnation efficiency of AASF/O2 yarn by 16.7%. In vitro drug release profiles show continuous and prolonged release of AMOX from AASF/O2/AMOX yarn up to 336 hours. In vitro hemolysis assay reveals that O2 plasma treatment and subsequent impregnation of AMOX do not affect the heertetmocompatibility of AASF yarn. The AASF/O2/AMOX yarn proves to be effective for in vitro growth inhibition of Staphylococcus aureus and Escherichia coli, whereas AASF offers no antibacterial activity against both types of bacteria. In vivo histopathology studies and colony-forming unit count data revealed accelerated wound healing activity of AASF/O2/AMOX over AASF yarn through rapid synthesis and proliferation of collagen, hair follicle, and connective tissues. CONCLUSION: Outcomes of this work clearly demonstrate the potential use of AASF/O2/AMOX yarn as a controlled antibiotic-releasing suture biomaterial for superficial surgical applications.

Highly effective antibiofilm coating of silver-polymer nanocomposite on polymeric medical devices deposited by one step plasma process.

Foley's catheters were coated with Silver (Ag), plasma polymerized aniline (PPAni) and Ag-PPAni composite by plasma based deposition processes which were characterized by XRD, EDX, SEM, and FT-IR spectroscopy and bioassays were performed to validate their efficacies to kill planktonic cells as well as to remove biofilm. The analyses confirmed the formation of Ag nanoparticles (AgNPs), PPAni and Ag-PPAni composite and also corroborated their successful deposition over the catheters. Antibacterial assays showed that coated catheters were capable of killing planktonic cells of most commonly encountered uropathogens and equally capable of eradicating biofilm formation by the uropathogens as evident from the reduced cfu/ml. UV-vis spectroscopy results showed that the nanoparticle coated catheters were capable of gradual release of AgNPs, killing all planktonic cells in solution over the time. Foley's catheters coated with AgNPs and their composites by one step plasma process were non-toxic devices capable of killing planktonic cells and proficient in eradicating biofilm formation which could be used to cutback the likelihood of the catheter related complications.

Immobilization of trypsin on plasma prepared Ag/PPAni nanocomposite film for efficient digestion of protein.

This work demonstrates the efficacy of a support matrix prepared by plasma process for trypsin immobilization without any surface activator. Plasma polymerization cum sputtering process is used to prepare the nanocomposite support matrix. Plasma sputtered silver nanoparticles (AgNPs) are uniformly embedded into plasma polymerized aniline (PPAni) film. Various characterization tools are employed to study the surface morphology, microstructure and chemical composition of the support matrices. Trypsin is immobilized onto the support matrix via the formation of covalent bond between them. Plasma generated free radicals on composite films activate the support matrix and make it efficient for increasing the tertiary enzyme stability via multipoint covalent attachment. Trypsin immobilized onto Ag/PPAni matrix has more hydrolyzing capacity of bovine serum albumin (BSA) than free trypsin as well as trypsin immobilized onto PPAni films.