Proceedings of 26th Annual Technological Advances in Science, Medicine and Engineering Conference 2022

3D-Printed metal implants coated with antibiotics for biomedical applications: Prevention of bacterial colonization and biofilm formation
Ishwor Poudel
Abstract
Surgical grade steel implants have been used for clinical procedures and surgical applications for decades, mainly in biomedical applications, due to their low carbon content, corrosion resistance, predefined safe composition, superior strength, and cost-effectiveness. 3D printing of metallic powder to prototype such constructs generally employs the powder bed fusion principle to melt and add layer by layer, resulting in the desired final implant. Even though advanced orthopedic medical device installation has become common during surgical procedures, complications like post-surgical infections (PSIs), bacterial growth and biofilm formation still result in implantation failures, predominantly due to Staph. species (1). These opportunistic nosocomial bacteria attack the local site, left vulnerable due to surgical openings, resulting in secondary surgery and increased hospital and healthcare burden. A crucial improvement possibility could be focused on bioactive coatings with microstructure modification of the implant surface, which has shown significant improvement in surface roughness for bio-adhesion, enhancing the bioactivity (2). Since PSIs are the primary concerns in implantation failure, adding antibiotics is a much-needed modification for local treatment of bacterial growth and inhibits the formation of notorious biofilm. Gentamicin is a potent model aminoglycoside that can counter bacterial adhesion and growth. The porous and rough 3D-printed surface allows deposition of polymers with improved coating adherence avoiding biofilm formation and also facilitates bone tissue growth around the surface (3). We fabricated 3D-printed SS implants functionalized with gentamicin coating and investigated the degree of antimicrobial efficacy and anti-biofilm efficacy against Staph. aureus and Staph. epidermidis.          3D-Printed implants were fabricated layer by layer from 316L powder using laser powder bed fusion-based Renishaw AM 250 machine. Gentamicin blended in PLGA (PLGA-GEN, 10%, 1.25mg/cm2) was deposited on the implant surface by using the airbrush spray technique. The surface coating was also characterized by morphological properties, surface wettability, and thermal analysis. The in vitro release profile of the drug was investigated in PBS (pH 7.4) as release media for 6 weeks, stirred at physiological temperature, maintaining the sink conditions, and showed sustained release throughout the period. The implants were coated and antimicrobial efficacy was determined using zone of inhibition measurements. The longevity of antimicrobial efficacy and the anti-biofilm efficacy of the coated implant surface was also studied. The implants demonstrated good antibacterial efficacy against Staph. aureus and Staph. epidermidis even while being loaded at lower concentrations, and the efficacy increased proportionally with the increase in drug loading. The initial burst release demonstrated a clear zone of inhibition formation in the first few days, appropriate for acute inhibition of bacterial growth. The longevity of gentamicin efficacy continued for a week when transplanted onto a fresh plate every day. The biofilm inhibition was observed for both species with PLGA-GEN coating compared to uncoated, PLGA-coated, and polished control surfaces. The biofilm inhibition was time-dependent as the extent of biofilm inhibition decreased on incubation in bacterial media for longer than three days.We fabricated 316L SS implants using additive manufacturing, coated with PLGA-GEN coating and tested for their gentamicin elution, antimicrobial efficacy, and biofilm inhibition. The results obtained were promising and radiate potential in biomedical applications.Keywords: 3D-printing, Polymeric-coating, Biofilm-inhibition

Last modified: 2022-08-20
Building: TASME Center
Room: Technology Hall
Date: August 28, 2022 - 11:20 AM – 11:35 AM

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