Rapid Isolation of Low-Level Carbapenem-Resistant E. coli from Water and Foods Using Glycan-Coated Magnetic Nanoparticles.

Carbapenem-resistant Enterobacterales (CRE) are one of the major global issues needing attention. Among them, carbapenemase-producing (CP) E. coli strains are commonly found in clinical and biological samples. Rapid and cost-effective detection of such strains is critical in minimizing their deleterious impact. While promising progress is being made in rapid detection platforms, separation and enrichment of bacteria are required to ensure the detection of low bacterial counts. The current separation methods, such as centrifugation, filtration, electrophoresis, and immunomagnetic separation, are often tedious, expensive, or ineffective for clinical and biological samples. Further, the extraction and concentration of antimicrobial-resistant bacteria (ARB) are not well documented. Thus, this study assessed the applicability of cost-effective glycan-coated magnetic nanoparticles (gMNPs) for simple and rapid extraction of CP E. coli. The study included two resistant (R)strains: Klebsiella pneumoniae carbapenemase (KPC)-producing E. coli (R: KPC) and New Delhi metallo-ß-lactamase (NDM)-producing E. coli (R: NDM). A susceptible E. coli (S) strain was used as a control, a reference bacterium. The gMNPs successfully extracted and concentrated E. coli (R) and E. coli (S) at low concentrations from large volumes of buffer solution, water, and food samples. The gMNPs concentrated up to two and five times their initial concentration for E. coli (R) and E. coli (S) in the buffer solution, respectively. In water and food samples, the concentration of E. coli (S) and E. coli (R) were similar and ranged 1-3 times their initial inoculation. A variation in the concentration from different food samples was seen, displaying the impact of food microstructure and natural microflora. The cost-effective and rapid bacterial cell capture by gMNPs was achieved in 15 min, and its successful binding to the bacterial cells in the buffer solution and food matrices was also confirmed using Transmission Electron Microscopy (TEM). These results show promising applications of gMNPs to extract pathogens and ARB from biological samples.

Nanoparticle-Based Plasmonic Biosensor for the Unamplified Genomic Detection of Carbapenem-Resistant Bacteria.

Antimicrobial resistance (AMR) is a global public health issue, and the rise of carbapenem-resistant bacteria needs attention. While progress is being made in the rapid detection of resistant bacteria, affordability and simplicity of detection still need to be addressed. This paper presents a nanoparticle-based plasmonic biosensor for detecting the carbapenemase-producing bacteria, particularly the beta-lactam Klebsiella pneumoniae carbapenemase (blaKPC) gene. The biosensor used dextrin-coated gold nanoparticles (GNPs) and an oligonucleotide probe specific to blaKPC to detect the target DNA in the sample within 30 min. The GNP-based plasmonic biosensor was tested in 47 bacterial isolates: 14 KPC-producing target bacteria and 33 non-target bacteria. The stability of GNPs, confirmed by the maintenance of their red appearance, indicated the presence of target DNA due to probe-binding and GNP protection. The absence of target DNA was indicated by the agglomeration of GNPs, corresponding to a color change from red to blue or purple. The plasmonic detection was quantified with absorbance spectra measurements. The biosensor successfully detected and differentiated the target from non-target samples with a detection limit of 2.5 ng/µL, equivalent to ~103 CFU/mL. The diagnostic sensitivity and specificity were found to be 79% and 97%, respectively. The GNP plasmonic biosensor is simple, rapid, and cost-effective in detecting blaKPC-positive bacteria.

Application of DNA sequences in anti-counterfeiting: Current progress and challenges.

Counterfeiting has never been more challenging than during the COVID-19 pandemic as counterfeit test kits and therapeutics have been discovered in the market. Current anti-counterfeiting labels have weaknesses: they can either be duplicated easily, are expensive or ill-suited for the existing complex supply chains. While RFID tags provide for an excellent alternative to current anti-counterfeiting methods, they can prove to be expensive and other routes involving nanomaterials can be difficult to encrypt. A DNA based anticounterfeiting system has significant advantages such as relative ease of synthesis and vast data storage abilities, along with great potential in encryption. Although DNA is equipped with such beneficial properties, major challenges that limit its real-world anti-counterfeiting applications include protection in harsh environments, rapid inexpensive sequence determination, and its attachment to products. This review elaborates the current progress of DNA based anti-counterfeiting systems and identifies technological gaps that need to be filled for its practical application. Progress made on addressing the primary challenges associated with the use of DNA, and potential solutions are discussed.