Introduction: There is a growing concern in using zinc oxide nanoparticles (ZnO NPs) for medical devices as alternative options in reducing hospital-acquired infections (HAIs). The commensal HAIs; Staphylococcus aureus (S.aureus) infect patients and lead to increased rates of morbidity and mortality. This study aims to investigate the antibacterial action of ZnO NPs in three different shapes; nanorod, nanoflakes and nanospheres impregnated in low-density polyethylene (LDPE) against S.aureus ATCC 25923. Methods: The antibacterial efficiency of ZnO NPs was studied through two standard test methods included were based on Clinical Laboratory Standards Institute (CLSI) guidelines MO2-A11 under light conditions of 5.70 w/m2 and American standard test method (ASTM) E-2149. Results: Preliminary screening did show a significant growth inhibition against S.aureus with ZnO NPs nanorod and nanoflakes, approximately in 7 to 8 mm zones of inhibition. Further analysis using ASTM E-2149 in dynamic conditions revealed variable activity depending on incubation treatment periods. It demonstrated the ZnO NPs in nanoflakes and nanosphere shape showed better inhibition against S.aureus with maximum reduction (100%). The FESEM results strongly suggest that the structure of ZnO nanoflakes and nanosphere played an importance role in nanomaterial-bacteria interaction which consequently cause cell membrane damage. Additionally, the irradiation under light treatment also enhance the generation of ROS and free radicals which helps the bactericidal activity against S.aureus. Conclusion: This study provides new insights for the antibacterial action of ZnO NPs/LDPE thin films in future biomedical appliances to reduce HAIs risks.
Antibacterial nanoparticle

Introduction: This study aims to investigate different residue sizes of β-tricalcium phosphate (β-TCP) micro-granules as carriers to assess antibacterial activity and drug-control release behavior of ampicillin (AMP-) and antimycotic (AMC-). Incorporation of antibiotic into the β-TCP micro-granules and it sustain release behavior could be used as alternative solution to reduce the risk of osteomyelitis and bone infections risks. Methods: Three different residue sizes (less than 300 µm, 300 µm and 600 µm) were prepared and coated with antibiotics solution (20 µg/µl of ampicillin and 100X antimycotic solution) by using two methods; dip and stream coating. After 72 h, 1.5 mL of distilled water was added to the treated (β-TCP) micro-granules at two different pH value (5.0 and 7.4). The extracted solution was further analyzed by Kirby Bauer disc diffusion test and spectrophotometer assay. Results: The solution containing AMC-(β-TCP) micro-granules with the size of 300 µm residue produced the largest inhibition zones against Escherichia coli (E. coli). All residue sizes coated with AMP- showed no antibacterial activity against both strains; Staphylococcus aureus (S. aureus) and E.coli. Additionally, the release behavior of AMC-(β-TCP) micro-granules was found not depending on the pH, but on the size of residue. Complete drug release was rapidly observed within 48 h. Conclusion: Based on this findings, it showed AMC-(β-TCP) micro-granules had an antibacterial activity against Gram-negative strain. Specifically, it can reduced the growth rate of E. coli and the rapid release behavior of AMC(β-TCP) micro-granules help in minimizing the risk-infections in early stage of implantation.