High-fidelity biosensing of dNTPs and nucleic acids by controllable subnanometer channel PaMscS

Direct and Continuous Monitoring of Multicomponent Antibiotic Gentamicin in Blood at Single-Molecule Resolution

Point-of-care monitoring of small molecules in biofluids is crucial for clinical diagnosis and treatment. However, the inherent low degree of recognition of small molecules and the complex composition of biofluids present significant obstacles for current detection technologies. Although nanopore sensing excels in the analysis of small molecules, the direct detection of small molecules in complex biofluids remains a challenge. In this study, we present a method for sensing the small molecule drug gentamicin in whole blood based on the mechanosensitive channel of small conductance in Pseudomonas aeruginosa (PaMscS) nanopore. PaMscS can directly detect gentamicin and distinguish its main components with only a monomethyl difference. The 'molecular sieve' structure of PaMscS enables the direct measurement of gentamicin in human whole blood within 10 min. Furthermore, a continuous monitoring device constructed based on PaMscS achieved continuous monitoring of gentamicin in live rats for approximately 2.5 h without blood consumption, while the drug components can be analyzed in situ. This approach enables rapid and convenient drug monitoring with single-molecule level resolution, which can significantly lower the threshold for drug concentration monitoring and promote more efficient drug use. Moreover, this work also lays the foundation for the future development of continuous monitoring technology with single-molecule level resolution in the living body.

Direct single-molecule detection of CoA-SH and ATP by the membrane proteins TMEM120A and TMEM120B

Membrane proteins are vital resources for developing biosensors. TMEM120A is a membrane protein associated with human pain transmission and lipid metabolism, and recent studies have demonstrated its ability to transport ions and bind to coenzyme A (COA-SH), indicating its potential to develop into a single-molecule sensor based on electrical methods. In this study, we investigated the ion transport properties of TMEM120A and its homolog TMEM120B on an artificial lipid bilayer using single-channel recording. The results demonstrate that both proteins can fuse into the lipid bilayer and generate stable ion currents under a bias voltage. Based on the stable ion transport capabilities of TMEM120A and TMEM120B, as well as the feature of TMEM120A binding with COA-SH, we developed these two proteins into a single-molecule sensor for detecting COA-SH and structurally similar molecules. We found that both COA-SH and ATP can reversibly bind to single TMEM120A and TMEM120B proteins embedded in the lipid bilayer and temporarily block ion currents during the binding process. By analyzing the current blocking signal, COA-SH and ATP can be identified at the single-molecule level. In conclusion, our work has provided two single-molecule biosensors for detecting COA-SH and ATP, offering insights for exploring and developing bio-inspired small molecule sensors.

Anti-bacterial mechanism of baicalin-tobramycin combination on carbapenem-resistant Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa (P. aeruginosa) is an important cause of nosocomial infections, and contributes to high morbidity and mortality, especially in intensive care units. P. aeruginosa is considered a 'critical' category bacterial pathogen by the World Health Organization to encourage an urgent need for research and development of new antibiotics against its infections.

AIM

To investigate the effectiveness of baicalin combined with tobramycin therapy as a potential treatment method for carbapenem-resistant P. aeruginosa (CRPA) infections.

METHODS

Polymerase chain reaction (PCR) and RT-PCR were used to detect the expression levels of drug-resistant genes (including VIM, IMP and OprD2) and biofilm-related genes (including algD, pslA and lasR) in CRPA that confer resistance to tobramycin, baicalin and tobramycin combined with baicalin (0, 1/8, 1/4, 1/2 and 1MIC).

RESULTS

There was a correlation between biofilm formation and the expression of biofilm-related genes. In addition, VIM, IMP, OprD2, algD, pslA and lasR that confer biofilm production under different concentrations in CRPA were significantly correlated. The synergistic effect of baicalin combined with tobramycin was a significant down-regulation of VIM, IMP, algD, pslA and lasR.

CONCLUSION

Baicalin combined with tobramycin therapy can be an effective treatment method for patients with CRPA infection.

Function Investigations and Applications of Membrane Proteins on Artificial Lipid Membranes

Membrane proteins play an important role in key cellular functions, such as signal transduction, apoptosis, and metabolism. Therefore, structural and functional studies of these proteins are essential in fields such as fundamental biology, medical science, pharmacology, biotechnology, and bioengineering. However, observing the precise elemental reactions and structures of membrane proteins is difficult, despite their functioning through interactions with various biomolecules in living cells. To investigate these properties, methodologies have been developed to study the functions of membrane proteins that have been purified from biological cells. In this paper, we introduce various methods for creating liposomes or lipid vesicles, from conventional to recent approaches, as well as techniques for reconstituting membrane proteins into artificial membranes. We also cover the different types of artificial membranes that can be used to observe the functions of reconstituted membrane proteins, including their structure, number of transmembrane domains, and functional type. Finally, we discuss the reconstitution of membrane proteins using a cell-free synthesis system and the reconstitution and function of multiple membrane proteins.

Biological nanopores for sensing applications

Biological nanopores are proteins with transmembrane pore that can be embedded in lipid bilayer. With the development of single-channel current measurement technologies, biological nanopores have been reconstituted into planar lipid bilayer and used for single-molecule sensing of various analytes and events such as single-molecule DNA sensing and sequencing. To improve the sensitivity for specific analytes, various engineered nanopore proteins and strategies are deployed. Here, we introduce the origin and principle of nanopore sensing technology as well as the structure and associated properties of frequently used protein nanopores. Furthermore, sensing strategies for different applications are reviewed, with focus on the alteration of buffer condition, protein engineering, and deployment of accessory proteins and adapter-assisted sensing. Finally, outlooks for de novo design of nanopore and nanopore beyond sensing are discussed.