Tamuleviciene, A. | bioRxiv Science

bioRxiv2024

Lateral Flow Assay Sensitivity and Signal Enhancement via Laser Micro-Machined Constrains in Nitrocellulose Membrane

Multiplex lateral flow assay (LFA) is a handful diagnostic technology that can identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other common respiratory viruses in one strip, which can be tested at the point-of-care without the need for equipment or skilled personnel outside the laboratory. Although its simplicity and practicality make it an appealing solution, it remains a grand challenge to substantially enhance the colorimetric LFA sensitivity. The local flow rate constraints imposed in nitrocellulose (NC) membranes via a number of vertical femtosecond laser micromachined microchannels are important for prolonged specific binding interactions. Porous NC membrane surfaces were structured with different widths and densities -channels employing a second harmonic of the Yb:KGW femtosecond laser and sample XYZ translation over a microscope objective-focused laser beam. The influence of the microchannel parameters on the vertical wicking speed was evaluated from the video recordings. The obtained results indicated that -channel length, width, and density in NC membranes controllably increased the immunological reaction time between the analyte and the labeled antibody by 950%. Image analysis of the colorimetric indicators confirmed that the flow rate delaying strategy enhanced the signal sensitives by 40% compared with pristine NC LFA. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/593095v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@a6105forg.highwire.dtl.DTLVardef@7cf449org.highwire.dtl.DTLVardef@189fa69org.highwire.dtl.DTLVardef@1973dbb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Antiviral and Antibacterial Efficacy of Nanocomposite Amorphous Carbon Films with Copper Nanoparticles

Copper compound-rich films and coatings are effective against widespread viruses and bacteria. Even though the killing mechanisms are still debated it is agreed that the metal ion, nanoparticle release, and surface effects are of paramount importance in the antiviral and antibacterial efficacy of the surfaces. In this work we have investigated the behaviour of the reactive magnetron sputtered nanocomposite diamond-like carbon thin films with copper nanoparticles (DLC:Cu). The films were etched employing oxygen plasma and/or exposed to ultra-pure water aiming to investigate the differences of the Cu release in the medium and changes in film morphology. The presence of metallic copper and Cu2O phases were confirmed by multiple analytical methods. Pristine films were more effective in the Cu release reaching up to 1.3 mg/L/cm2 concentration. Plasma processing resulted in the oxidation of the films which released less Cu but after exposure to water, their average roughness increased more, up to 5.5 nm. Pristine and O2 plasma processed DLC:Cu films were effective against both model coronavirus and herpesvirus after 1-hour contact time and reached virus reduction up to 2.23 and 1.63 log10, respectively. Pristine DLC:Cu films were more effective than plasma-processed ones against herpesvirus, while less expressed difference was found for coronavirus. The virucidal efficacy over up to 24 h exposures in the aqueous medium was validated. A bactericidal study confirmed that pristine DLC:Cu films were effective against gram-negative E. coli and gram-positive E. faecalis bacteria. After 3 hours 100% antibacterial efficiency (ABE) was obtained for E. coli and 99.97% for E. faecalis. After 8 hours and longer exposures, 100% ABE was reached. The half-life inactivation of viruses was 8.10 - 11.08 minutes and for E. faecalis 15.1 - 72.2 minutes.

microbiology↗