Control of microbial agents by functionalization of commercial air filters with metal oxide particles

Role of Antimicrobial Air Purifier in Reducing the Microbial Load in the Critical Care Unit in Oncology Center: An Intervention Study

Introduction

High quality and effective ventilation system operation plays a major role in maintaining indoor air quality in critical care unit (CCU). Aim of this study was to detect the role of antimicrobial-air-purifier in reducing the colony counts of microbes in air and high surface.

Methods

This prospective study was conducted in CCU over a period of 18 months from November 2022 to May 2024 after approval from Hospital Ethics Committee. Microbial load was tested in CCU in the presence of and absence of purifier and air/high touch surface sampling was done by using settle-plate method on consecutive days in two phases (with/without purifier). Microorganism culture and identification was done using VITEK-2, and colony counting was performed using Omeliansky formula.

Results

The comparison of microbial load in the CCUs between two phases revealed significant difference in the air and surface on days 1, 7, 14, 30, and 60 (p < 0.0001). Among gram-positive cocci (GPC), the most common isolate identified was coagulase-negative Staphylococcus species [35 (92.10%)], followed by Micrococcus luteus [5 (13.15%)] and Staphylococcus aureus [1 (2.63%)]. All GPC were resistant to methicillin and erythromycin while 1 (5%) strain was resistant to vancomycin, teicoplanin, and linezolid. Among gram-negative bacilli (GNB), the most common isolate was Acinetobacter species [8/23 (34.78%)], followed by P. species [5 (21.74%)]. About 19-23 (85-100%) GNB strains were resistant to third-generation cephalosporins and beta-lactam and beta-lactamase inhibitors. About 9-15 (42.3-67.64%) were resistant to tigecycline and carbapenems. Decreased bloodstream infections/catheter-associated urinary tract infections (CAUTI) rate of 3.49-2.92/3.97-1.95/1,000 patient-days was observed in CCU, while the device utilization ratio was same.

Conclusion

Antimicrobial air purifier showed an effective role in decreasing the central line-associated blood stream infections and CAUTI rates in CCU.

How to cite this article

Batra VB, Kirtania J, Tiwari S, Kumar P, Kumar A, Chakraborty S. Role of Antimicrobial Air Purifier in Reducing the Microbial Load in the Critical Care Unit in Oncology Center: An Intervention Study. Indian J Crit Care Med 2025;29(4):327-332.

Opportunities for nanomaterials in more sustainable aviation

New materials for electrical conductors, energy storage, thermal management, and structural elements are required for increased electrification and non-fossil fuel use in transport. Appropriately assembled as macrostructures, nanomaterials can fill these gaps. Here, we critically review the materials science challenges to bridge the scale between the nanomaterials and the large-area components required for applications. We introduce a helpful classification based on three main macroscopic formats (fillers in a matrix, random sheets or aligned fibres) of high-aspect ratio nanoparticles, and the corresponding range of bulk properties from the commodity polymer to the high-performance fibre range. We review progress over two decades on macroscopic solids of nanomaterials (CNTs, graphene, nanowires, etc.), providing a framework to rationalise the transfer of their molecular-scale properties to the scale of engineering components and discussing strategies that overcome the envelope of current aerospace materials. Macroscopic materials in the form of organised networks of high aspect ratio nanomaterials have higher energy density than regular electrodes, superior mechanical properties to the best carbon fibres, and electrical and thermal conductivity above metals. Discussion on extended electrical properties focuses on nanocarbon-based materials (e.g., doped or metal-hybridised) as power or protective conductors and on conductive nanoinks for integrated conductors. Nanocomposite electrodes are enablers of hybrid/electric propulsion by eliminating electrical transport limitations, stabilising emerging high energy density battery electrodes, through high-power pseudocapacitive nanostructured networks, or downsizing Pt-free catalysts in flying fuel cells. Thermal management required in electrified aircraft calls for nanofluids and loop heat pipes of nanoporous conductors. Semi-industrial interlaminar reinforcement using nanomaterials addresses present structural components. Estimated improvements for mid-range aircraft include > 1 tonne weight reduction, eliminating hundreds of CO2 tonnes released per year and supporting hybrid/electric propulsion by 2035.

Construction of Vine-Inspired Antimicrobial Filter with Multiscale 3D Nanonetwork for High-Efficiency Air Filtration

Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuOx) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuOx was spontaneously enwound on GF, and ChNF@CuOx itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuOx/GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus, Escherichia coli, and Candida albicans due to the urchin-like in situ grown CuOx on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuOx enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.