•The RNA riboswitch based electrochemical biosensor could realize label-free c-di-GMP detection.•The biosensor can detect c-di-GMP with highly sensitivity and specificity.•The biosensor can be easily fabricated with low cost.•The designed biosensor has an effective measuring range with low detection limit than previous reports.Cyclic diguanylate monophosphate (c-di-GMP) is an important second messenger that regulates a variety of complex physiological processes involved in motility, virulence, biofilm formation and cell cycle progression in several bacteria. Herein we report a simple label-free and self-assembled RNA riboswitch-based biosensor for sensitive and selective detection of c-di-GMP. The detectable concentration range of c-di-GMP is from 50 nM to 1 μM with a detection limit of 50 nM.

•The RNA aptamer based electrochemical biosensor could realize label-free cAMP detection.•The biosensor can detect cAMP with highly sensitivity and specificity.•The biosensor can be easily fabricated with low cost and repeated usability.•The designed aptasensor has a wide effective measuring range with extremely low detection limit.Cyclic adenosine monophosphate (cAMP) is an important small biological molecule associated with the healthy state of living organism. In order to realize highly sensitive and specific detection of cAMP, here an RNA aptamer and electrochemical impedance spectroscopy (EIS) based biosensor enhanced by gold nanoparticles electrodeposited on the surface of gold electrode is designed. The designed aptasensor has a wide effective measuring range from 50 pM to 250 pM with a detection limit of 50 pM in PBS buffer, and an effective measuring range from 50 nM to 1 μM with a detection limit of 50 nM in serum. The designed biosensor is also able to detect cAMP with high sensitivity, specificity, and stability. Since the biosensor can be easily fabricated with low cost and repeatedly used for at least two times, it owns great potential in wide application fields such as clinical test and food inspection, etc.

Phase distribution detection of cells and tissues is concerned since it is an important auxiliary method for observing biological samples. High speed and large amount cell detection is needed for its high detecting efficiency. In this paper, we have proposed a simple large scale biological sample phase detection device called gravity driven high throughput phase detecting cytometer based on quantitative interferometric microscopy to obtain flowing red blood cells phase. The system could realize high throughput phase detecting and statistical analysis with high detecting speed and in real time. The statistical characteristics of red blood cells could be obtained which might be helpful for biological analysis and disease detection. We believe this method is a powerful tool to quantitatively measure the phase distribution of biological samples.

•We reported beacon–AuNPs for highly sensitive and rapid bacterial detection.•The beacon–AuNPs are 1000-folds sensitive than using molecular beacon directly.•The beacon–AuNPs can recognize bacteria within an hour.•The beacon–AuNPs have high specificity and anti-interference.Since many diseases are caused by pathogenic bacterial infections, accurate and rapid detection of pathogenic bacteria is in urgent need to timely apply appropriate treatments and to reduce economic costs. To end this, we designed molecular beacon–Au nanoparticle hybrid nanoprobes to improve the bacterial detection efficiency and sensitivity. Here, we show that the designed molecular beacon modified Au nanoparticles could specifically recognize synthetic DNAs targets and can readily detect targets in clinical samples. Moreover, the hybrid nanoprobes can recognize Escherichia coli within an hour at a concentration of 102 cfu/ml, which is 1000-folds sensitive than using molecular beacon directly. Our results show that the molecular beacon–Au nanoparticle hybrid nanoprobes have great potential in medical and biological applications.