Comparison of isothermal microcalorimetry and BACTEC MGIT960 for the detection of the metabolic activity of Mycobacterium tuberculosis in sputum samples

The construction of CRISPR/Cas9-mediated FRET 16S rDNA sensor for detection of Mycobacterium tuberculosis

The simple and efficient detection of nucleic acids is important in the diagnosis of tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tuberculosis). However, base mismatch will lead to false positive and false negative nucleic acid test, which seriously interferes with the accuracy of the final results. Herein, we demonstrated a CRISPR/Cas-9-mediated fluorescent strategy utilizing fluorescence resonance energy transfer (FRET) for the detection of bacteria. High-variable region of M. tuberculosis 16S rDNA fragment was used as the target, and CRISPR/Cas9 was used as the recognition element. The binding of the P1 probe of upconversion nanoparticles (UCNPs) @SiO₂-P1 and the P2 probe of Fe₃O₄@Au-P2 caused the fluorescence quenching of UCNPs. In the presence of the target, the P2 probe hybridized with the target to form double-stranded DNA (dsDNA), which was recognized and cleaved by CRISPR/Cas9, resulting in the breaking of the P1-P2 duplex linkage. UCNPs moved away from Fe₃O₄@Au under a magnetic field, and the fluorescence signal was restored; bacteria were detected under the excitation of a 980 nm laser source. Using the CRISPR/Cas-9-mediated system, the sensor could distinguish single-base mismatches in 10 bases from the protospacer adjacent motif (PAM) region. The limit of detection (LOD) was 20 CFU mL^-1 and the detection time was 2 h. It developed a new way of accurate nucleic acid detection for disease diagnosis.

Analytical methods for assessing antimicrobial activity of nanomaterials in complex media: advances, challenges, and perspectives

Assessing the antimicrobial activity of engineered nanomaterials (ENMs), especially in realistic scenarios, is of great significance for both basic research and applications. Multiple analytical methods are available for analysis via off-line or on-line measurements. Real-world samples are often complex with inorganic and organic components, which complicates the measurements of microbial viability and/or metabolic activity. This article highlights the recent advances achieved in analytical methods including typical applications and specifics regarding their accuracy, cost, efficiency, and user-friendliness. Methodological drawbacks, technique gaps, and future perspectives are also discussed. This review aims to help researchers select suitable methods for gaining insight into antimicrobial activities of targeted ENMs in artificial and natural complex matrices.

Integrating Thermal Sensors in a Microplate Format: Simultaneous Real-Time Quantification of Cell Number and Metabolic Activity

Microplates have become a standard tool in the pharmaceutical industry and academia for a broad range of screening assays. One of the most commonly performed assays is the cell proliferation assay, which is often used for the purpose of drug discovery. Microplate readers play a crucial role in this field, as they enable high-throughput testing of large sample numbers. Common drawbacks of the most popular plate reader technologies are that they are end-point-based and most often require the use of detection reagents. As a solution, with this work, we aim to expand the possibilities of real-time and label-free monitoring of cell proliferation inside a microplate format by introducing a novel thermal-based sensing approach. For this purpose, we have developed thin-film sensors that can easily be integrated into the bottom of standard 96-well plates. First, the accuracy and precision of the sensors for measuring temperature and thermal effusivity are assessed via characterization experiments. These experiments highlight the fast response of the sensors to changes in temperature and thermal effusivity, as well as the excellent reproducibility between different sensors. Later, proof-of-principle measurements were performed on the proliferation of Saccharomyces cerevisiae. The proliferation measurements show that the thermal sensors were able to simultaneously detect relative changes in cell number as well as changes in metabolic activity. This dual functionality makes the presented sensor technology a promising candidate for monitoring microplate assays.

Cell Temperature Measurement for Biometabolism Monitoring

Temperature is an important factor in the process of life, as thermal energy transfer participates in all biological events in organisms. Due to technical limitations, there is still a lot more information to be explored regarding the correlation between life activities and temperature changes. In recent years, the emergence of a variety of new temperature measurement methods has facilitated further research in this field. Here, we introduce the latest advances in temperature sensors for biological detection and their related applications in metabolic research. Various technologies are discussed in terms of their advantages and shortcomings, and future prospects are presented.