There
is a significant and growing research interest in the isolation of
extracellular vesicles (EVs) from large volumes of biological samples
and their subsequent concentration into clean and small volumes of
buffers, especially for applications in medical diagnostics. Materials
that are easily incorporated into simple sampling devices and which
allow the release of EVs without the need for auxiliary and hence
contaminating reagents are particularly in demand. Herein, we report
on the design and fabrication of a flexible, microporous, electrochemically
switchable cloth that addresses the key challenges in diagnostic applications
of EVs. We demonstrate the utility of our electrochemically switchable
substrate for the fast, selective, nondestructive, and efficient capture
and subsequent release of EVs. The substrate consists of an electrospun
cloth, infused with a conducting polymer and decorated with gold particles.
Utilizing gold–sulfur covalent bonding, the electrospun substrates
may be functionalized with SH-terminated aptamer probes selective
to EV surface proteins. We demonstrate that EVs derived from primary
human dermal fibroblast (HDFa) and breast cancer (MCF-7) cell lines
are selectively captured with low nonspecific adsorption using an
aptamer specific to the CD63 protein expressed on the EV membranes.
The specific aptamer–EV interactions enable easy removal of
the nonspecifically bound material through washing steps. The conducting
polymer component of the cloth provides a means for efficient (>92%)
and fast (<5 min) electrochemical release of clean and intact captured
EVs by cathodic cleavage of the Au–S bond. We demonstrate successful
capture of diluted EVs from a large volume sample and their release
into a small volume of clean phosphate-buffered saline buffer. The
developed cloth can easily be incorporated into different designs
for separation systems and would be adaptable to other biological
entities including cells and other EVs. Furthermore, the capture/release
capability holds great promise for liquid biopsies if used to targeted
disease-specific markers.
The increase in health care-associated infections and antibiotic resistance has led to a growing interest in the search for innovative technologies to solve these problems. In recent years, the interest of the scientific community has focused on violet–blue light at 405 nm (VBL405). This study aimed to assess the VBL405 efficiency in reducing microbial growth on surfaces and air. This descriptive study run between July and October 2020. Petri dishes were contaminated with P. aeruginosa, E. coli, S. aureus, S. typhimurium, K. pneumoniae and were placed at 2 and 3 m from a LED light source having a wavelength peak at 405 nm and an irradiance respectively of 967 and 497 µW/cm2. Simultaneously, the air in the room was sampled for 5 days with two air samplers (SAS) before and after the exposition to the VBL405 source. The highest microbial reduction was reached 2 m directly under the light source: S. typhimurium (2.93 log10), K. pneumoniae (2.30 log10), S. aureus (3.98 log10), E. coli (3.83 log10), P. aeruginosa (3.86 log10). At a distance of 3 m from the light source, the greatest reduction was observed for S. aureus (3.49 log10), and P. aeruginosa (3.80 log10). An average percent microbial reduction of about 70% was found in the sampled air after 12 h of exposure to VBL405. VBL405 has proven to contrast microbial growth on the plates. Implementing this technology in the environment to provide continuous disinfection and to control microbial presence, even in the presence of people, may be an innovative solution.
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