MPA-capped CdSe QD/mercaptoethylamine-capped AuNP nanocomposite-based sensor for instant detection of trinitrotoluene

A sensitive fluorescence "turn on" nanosensor for glutathione detection based on Ce-MOF and gold nanoparticles

Glutathione (GSH) as an essential biothiol maintains redox homeostasis in human body, the aberrant level of it has been related to various diseases. In this work, we constructed a facile and environment-friendly strategy by using Ce based metal-organic frameworks and gold nanoparticles (AuNPs) for detection of GSH. The fluorescence intensity of the Ce-MOF was quenched by AuNPs, which is ascribed to the existence of fluorescence resonance energy transfer (FRET) and electrostatic interaction between Ce-MOFs and AuNPS. Because of the formation of Au-SH between AuNPs and GSH, the addition GSH induced the Ce-MOF/AuNPs and prevented the occurrence of FRET and electrostatic interaction between Ce-MOFs and AuNPS, which futher recovered the fluorescence of Ce-MOF. Under the optimized conditions, this "turn-on" sensing process revealed a high selectivity toward GSH and displayed good linearity in range of 0.2-32.5 μM with low detection limit of 58 nM. In addition, the practicability of the strategy was testified through analyzing GSH in real human serum samples.

Development of a pulse-induced electrochemical biosensor based on gluconamide for Gram-negative bacteria detection

Pathogenic bacteria can cause the outbreaks of disease and threaten human health, which stimulates the development of advanced detection techniques. Herein, a specific and sensitive electrochemical biosensor for Gram-negative bacteria was established based on the conductive polymer with artificial muscle properties.  The effective recognition was achieved through the specific carbohydrate-carbohydrate interaction between gluconamide and lipopolysaccharide.  The application of impulse voltage enhances the efficiency of recognition and shortens the detection time through the temporary deformation of the electrode surface, with a limit of detection (LOD)  of 1 × 10⁰ CFU/mL and a linear range of 1 × 10⁰ - 1 × 10⁶ CFU/mL for Escherichia coli (E. coli). In addition  to the merits of low cost, high efficiency, and rapidity,  the developed label-free electrochemical biosensor can also be applicable for other Gram-negative bacteria, owning promising potential in the application of portable devices and paving a potential way for the construction of electrochemical biosensors.

Recent Developments in the Field of Explosive Trace Detection

Explosive trace detection (ETD) technologies play a vital role in maintaining national security. ETD remains an active research area with many analytical techniques in operational use. This review details the latest advances in animal olfactory, ion mobility spectrometry (IMS), and Raman and colorimetric detection methods. Developments in optical, biological, electrochemical, mass, and thermal sensors are also covered in addition to the use of nanomaterials technology. Commercially available systems are presented as examples of current detection capabilities and as benchmarks for improvement. Attention is also drawn to recent collaborative projects involving government, academia, and industry to highlight the emergence of multimodal screening approaches and applications. The objective of the review is to provide a comprehensive overview of ETD by highlighting challenges in ETD and providing an understanding of the principles, advantages, and limitations of each technology and relating this to current systems.

Nitrogen-doped carbon quantum dots conjugated isoreticular metal-organic framework-3 particles based luminescent probe for selective sensing of trinitrotoluene explosive

Amine group-containing isoreticular metal-organic framework (IRMOF-3) particles are utilized for the first time as a trinitrotoluene (TNT) sensing material. IRMOF-3 particles are synthesized using zinc nitrate as a metal precursor and 2-amino-1,4-benzenedicarboxylic acid as a linker. The nitrogen-doped carbon quantum dots (NCQDs) are synthesized from citric acid and ethylenediamine as carbon and nitrogen precursor, respectively. The NCQDs are conjugated with IRMOF-3 particles as IRMOF-3/NCQDs. The TEM micrograph revealed the average size of IRMOF-3 particles to be 363.66 nm. The photoluminescence emission intensity of IRMOF-3 particles at λ_em 430 nm is highly increased in the presence of NCQDs (λ_ex 330 nm). Both the as-synthesized IRMOF-3 and IRMOF-3/NCQD particles are explored for TNT detection to compare the effect of NCQDs on the IRMOF-3 particle surface. Lower limit of detection (7.5 × 10^-8 M) and higher Stern-Volmer constant (4.46 × 10⁶ M^-1) are achieved by IRMOF-3/NCQD particles. The association constant also increased from 5.3 × 10⁴ to 2.78 × 10⁶ M^-1 after the conjugation of IRMOF-3 particles with NCQDs. Moreover, enhanced selectivity for TNT over trinitrophenol is achieved using the IRMOF-3/NCQD particles. Graphical Abstract.