Analytical Chemistry最新文献

Near-infrared light (NIR)-driven photoelectrochemical (PEC) processes are mainly faced with the limitation of weak photocurrents. Here, N-deficient B-doped g-C₃N₄/CdS (NB-g-C₃N₄/CdS) is proposed to construct a NIR-driven PEC biosensor assisted by CRISPR-Cas12a system for the determination of microRNA-21 (miRNA-21). To promote the optical absorption as well as the separation of photogenerated electrons and holes of g-C₃N₄, NB-g-C₃N₄/CdS is constructed via engineering the electronic and band structure in terms of N defect, B doping, and heterojunction, achieving high PEC performance. To obtain the high luminescence efficiency for exciting NB-g-C₃N₄/CdS under NIR, the core-shell NaYF₄:Yb³⁺, Tm³⁺@NaYF₄ upconversion nanoparticles (UCNPs) with repaired defects are prepared. Furthermore, the rolling circle amplification (RCA)-assisted CRISPR-Cas12a system is integrated to fragment the DNA on UCNPs, achieving sensitive detection of miRNA-21. On the one hand, the uncleavaged signal probes on UCNPs combined with NB-g-C₃N₄/CdS through π-π stacking interaction, generating photocurrents under the irradiation of NIR. On the other hand, the cleavaged signal probes which cannot link with NB-g-C₃N₄/CdS exhibited the fluorescence (FL) signals. The proposed PEC-FL dual-mode biosensor provides a mutual authentication of testing results and demonstrates ultrasensitivity (the detection limit of 1.1 fM for PEC mode and 7.0 fM for FL mode) and excellent specificity, which is promising in the clinical analysis of miRNA.

As a highly aggressive malignancy, the issue of curing melanoma at an advanced stage could suffer from severe metastasis and a lower 5-year survival rate. Therefore, the early diagnosis of melanoma with high accuracy is vital and contributes to a significantly improved 5-year survival rate. This work reports a dual-locked receptor, m-BA-Hcy, which releases the near-infrared (NIR) fluorophore Hcy-OH upon the dual activation of reactive oxygen species (ROS) and tyrosinase (TYR). The substitution of boric acid on the phenyl ring was studied, which influences the feasibility of the performance of the envisaged cascade reaction. The sensing behavior was discussed in terms of optical spectroscopy and reaction mechanism, and imaging was fully performed at the cellular and organism levels. Receptor m-BA-Hcy was hence clarified to possess supreme sensitivity and accuracy for melanoma detection.

The pore microstructure of mesoporous materials has a vital influence on molecular movement and assembly as well as crystallization. Nonetheless, previous studies have predominantly concentrated on the impact of pore size and pore shape on molecular assembly and nucleation outcomes; investigations delving into the effects of more complex pore structures on molecular assembly and nucleation behaviors were absent. In this study, evolution of the molecular self-assembly process of flufenamic acid (FFA) confined in mesoporous materials with different microstructures was monitored by in situ ¹⁹F solid-state NMR spectroscopy. It was demonstrated that tortuosity, as a microstructural parameter of porous materials, has the ability to determine the molecular assembly process and nucleation behaviors of FFA. The results indicated that molecules in pores with high tortuosity tend to aggregate to an amorphous plug, while those in less tortuous nanopores are inclined to adsorb on the pore surface forming molecular layers. Besides that, this work provides the first direct proof that a mixture of two molecular layer structures exists on the FFA-silica surface through ¹⁹F solid-state NMR spectroscopy. This study explores the relationship between the microstructure of porous materials and molecular assembly, which can inform drug delivery, electronic deposition, and biomineralization.

The acetone present in exhaled breath is a promising indicator for diagnosing human health. The fluorescent hydrogel sensor-based portable sensing platform is a highly effective tool for the on-site detection of acetone. However, existing hydrogel sensors are often limited by their irreversibility and autofluorescence. This study constructed an upconversion nanoprobe with reversibility for dual-mode detection of acetone by simply combining upconversion nanoparticles (UCNPs), hydroxylamine sulfate, and thymol blue (TB). The nanoprobe was further embedded into a hydrogel network to construct the background-free hydrogel nanosensor for the portable detection of acetone. The hydrogel nanosensor utilized long-wavelength-excited UCNPs to avoid self-luminescence interference. Hydroxylamine sulfate, as a specific recognition unit, reacted with acetone to induce the protonation of TB, resulting in an increase in absorbance at 548 nm and a decrease in luminescence at 540 nm, enabling visual colorimetric and precise luminescent detection of acetone. Moreover, the hydrogel nanosensor could be restored to its initial state through the deprotonation of TB, thereby achieving reversible detection. Additionally, 3D printing technology was utilized to construct a portable sensing platform for real-time acetone monitoring. The proposed upconversion hydrogel nanosensor in this study paves a new way for developing hydrogel sensors with high sensitivity and reversibility.