Latest ArticlesEnvironment-sensitive fluorescent probes are commonly utilized in various fields, including fluorescence sensing and imaging. This paper describes the synthesis and photophysical properties of a novel class of solvatochromic fluorophores that incorporate biisoindolylidene as the core backbone. This study investigates the structure-property relationships of these newly developed fluorophores. The central biisoindolylidene acts as an efficient electron acceptor, and by modifying the aryl ring substituent at the 3,3′ position, the photophysical properties of the fluorophores can be significantly enhanced, particularly in terms of photoluminescence quantum efficiency. Furthermore, when an electron-donor group replaces the aryl ring at the 3,3′ position, intriguing solvatochromic behavior is observed. This leads to a red-shift in the maximum emission wavelength and an increase in the Stokes shift with increasing solvent polarity. In solvent dimethyl sulfoxide (DMSO), the maximum emission wavelength can reach up to 750 nm, with a Stokes shift of approximately 150 nm. Finally, the potential application of the fluorophore in the detection of volatile acids is explored in a preliminary manner.
Ultrasensitive detection of nucleic acids is of great significance for precision medicine. Digital polymerase chain reaction (dPCR) is the most sensitive method but requires sophisticated and expensive instruments and a long reaction time. Digital PCR-free technologies, which mean the digital assay not relying on thermal cycling to amplify the signal for quantitative detection of nucleic acids at the single-molecule level, include the digital isothermal amplification techniques (dIATs) and the digital clustered regularly interspaced short palindromic repeats (CRISPR) technologies. They combine the advantages of dPCR and IATs, which could be fast and simple, enabling absolute quantification of nucleic acids at a single-molecule level with minimum instrument, representing the next-generation molecular diagnostic technology. Herein, we systematically summarized the strategies and applications of various dIATs, including the digital loop-mediated isothermal amplification (dLAMP), the digital recombinase polymerase amplification (dRPA), the digital rolling circle amplification (dRCA), the digital nucleic acid sequence-based amplification (dNASBA) and the digital multiple displacement amplification (dMDA), and evaluated the pros and cons of each method. The emerging digital CRISPR technologies, including the detection mechanism of CRISPR and the various strategies for signal amplification, are also introduced comprehensively in this review. The current challenges as well as the future perspectives of the digital PCR-free technology were discussed.
The extracellular vesicles show great potential as a noninvasive biomarker for the early detection of cancer. Hence, there is an urgent requirement to create biosensors that are time-saving, simple, and easily scalable in order to accomplish rapid, sensitive, and quantitative detection of extracellular vesicles. In this study, we present a self-propelled DNA walker powered by endonuclease Nt.BbvCI, which enables the development of a "signal on" sensing platform for the rapid and highly sensitive detection of extracellular vesicles. The DNA motor employed tracks made of streptavidin magnetic beads, which consisted of substrate strands labeled with fluorescein and motor strands locked by aptamers. The aptamer recognition of the target protein on extracellular vesicles unlocked the motor strand, initiating the DNA motor process. After replacing the optimal buffer solution containing the endonuclease Nt.BbvCI, the motor strands autonomously moved along the streptavidin magnetic beads track, continuously releasing fluorescent molecules and producing detectable fluorescence signals. Under optimal conditions, the detection range was from 2×104 particles/mL to 2×109 particles/mL, with a detection limit of 2.9×103 particles/mL, demonstrating excellent selectivity. This method has demonstrated good selectivity in different tumor-derived extracellular vesicles and performs well in complex biological samples. The ability to effectively analyze surface proteins of extracellular vesicles in a short period of time gives our DNA walker a tremendous potential for developing simple and cost-effective clinical diagnostic devices.
The interface modulation significantly affects the photocatalytic performances of supported metal phthalocyanines (MPc)-based systems. Herein, ZnPc was loaded on nanosized Au-modified TiO2 nanosheets (Au-T) to obtain wide-spectrum ZnPc/Au-T photocatalysts. Compared with large Au NP (8 nm)-mediated ZnPc/Au-T photocatalyst, ultrasmall Au NP (3 nm)-mediated one shows advantageous photoactivity, achieving 3- and 10-fold CO2 conversion rates compared with reference ZnPc/T and pristine TiO2 nanosheets, respectively. Employing monochromatic beam-assisted surface photovoltage and photocurrent action, etc., the introduction of ultrasmall Au NPs more effectively facilitates intrinsic interfacial charge transfer. Moreover, ZnPc molecules are found more dispersed with the existence of small Au NPs hence exposing abundant Zn2+sites as the catalytic center for CO2 reduction. This work provides a feasible design strategy and renewed recognition for supported MPc-based photocatalyst systems.
Innovative anti-cancer therapies that activate the immune system show promise in combating cancers resistant to conventional treatments. Photodynamic therapy (PDT) is one such treatment, which not only directly eliminates tumor cells but also functions as an in situ tumor vaccine by enhancing tumor immunogenicity and triggering anti-tumor immune responses through immunogenic cell death (ICD). However, the effectiveness of PDT in enhancing immune responses is influenced by factors, such as photosensitizers and the tumor microenvironment, particularly hypoxia. Current clinically used PDT heavily relies on oxygen (O2) availability and can be limited by tumor hypoxia. Additionally, the tumor immunosuppressive microenvironment induced by hypoxia affects the anti-tumor immunity of tumor-infiltrating effector T cells. Meanwhile, the immunosuppressive myeloid-lineage cells are recruited to the hypoxic tumor tissue and exhibit higher immunosuppressive capabilities under hypoxia conditions. Consequently, numerous strategies have been developed to modulate tumor hypoxia or to create hypoxia-compatible PDT, aiming to reduce the effects of tumor hypoxia on PDT-driven immunotherapy. This review investigates these strategies, including approaches to alleviate, exploit, and disregard tumor hypoxia within the context of PDT/immunotherapy. It also emphasizes the role of advanced nanomedicine and its benefits in these strategies, while outlining current challenges and future prospects in the field.
In this work, an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction (eNO3RR) for synthesis of ammonia (NH3) under ambient conditions. The substrate of MnOOH plays an important role on the size and electronic structure of Cu nanoparticles, where Cu has the ultrafine size of 2.2 nm and positive shift of its valence states, which in turn causes the increased number of Cu active sites and enhanced intrinsic activity of every active site. As a result, this catalyst realizes an excellent catalytic performance on eNO3RR with the maximal NH3 Faraday efficiency (FE) (96.8%) and the highest yield rate (55.51 mg h−1 cm−2) at a large NH3 partial current density of 700 mA/cm2, which could help to promote the industrialization of NH3 production under ambient conditions.
The complexity of living environment system demands higher requirements for the sensitivity and selectivity of the probe. Therefore, it is of great importance to develop a universal strategy for high-performance probe optimization. Herein, we propose a novel “Enrichment-enhanced Detection” strategy and use carbon dots-dopamine detection system as a representative model to evaluate its feasibility. The composite probe carbon dots (CDs)-encapsulated in glycol-chitosan (GC) (i.e., CDs@GC) was obtained by simply mixing GC and CDs through noncovalent interactions, including electrostatic interactions and hydrogen bonding. Dopamine (DA) could be detected through internal filter effect (IFE)-induced quenching of CDs. In the case of CDs@GC, noncovalent interactions (electrostatic interactions) between GC and the formed quinone (oxide of DA) could selectively extract and enrich the local concentration of DA, thus effectively improving the sensitivity and selectivity of the sensing system. The nanosensor had a low detection limit of 3.7 nmol/L, which was a 12-fold sensitivity improvement compared to the bare CDs probes with similar fluorescent profiles, proving the feasibility of the “Enrichment-enhanced Detection” strategy. Further, to examine this theory in real case, we designed a highly portable sensing platform to realize visual determination of DA. Overall, our work introduces a new strategy for accurately detecting DA and provides valuable insights for the universal design and optimization of superior nanoprobes.
Current research primarily focuses on emerging organic pollutants, with limited attention to emerging inorganic pollutants (EIPs). However, due to advances in detection technology and the escalating environmental and health challenges posed by pollution, there is a growing interest in treating waters contaminated with EIPs. This paper explores biochar characteristics and modification methods, encompassing physical, chemical, and biological approaches for adsorbing EIPs. It offers a comprehensive review of research advancements in employing biochar for EIPs remediation in water, outlines the adsorption mechanisms of EIPs by biochar, and presents an environmental and economic analysis. It can be concluded that using biochar for the adsorption of EIPs in wastewater exhibits promising potential. Nonetheless, it is noteworthy that certain EIPs like Au(Ⅲ), Rh(Ⅲ), Ir(Ⅲ), Ru(Ⅲ), Os(Ⅲ), Sc(Ⅲ), and Y(Ⅲ), have not been extensively investigated regarding their adsorption onto biochar. This comprehensive review will catalyze further inquiry into the biochar-based adsorption of EIPs, addressing current research deficiencies and advancing the practical implementation of biochar as a potent substrate for EIP removal from wastewater streams.
Carbon dioxide photocatalytic reduction (CO2-PR) is an efficient method for controlling CO2 emissions and generating cleaner energy while mitigating global warming. Tungsten oxides (WxOy) have attracted considerable attention for CO2-PR due to their excellent spectral absorbance. However, comprehensive reviews are lacking on the use of WxOy for CO2-PR. Therefore, this review provides a detailed summary of t research progress made with WxOy-based catalysts in CO2-PR. It also explains the fundamental principles of CO2-PR and evaluates key performance indicators that affect the activity of WxOy-based photocatalysts, including yield, selectivity, stability, and apparent quantum yield. Additionally, this review explores opportunities for synthesizing high-performance WxOy-based photocatalysts and highlights their potential for the green preparation of C1/C2 products through CO2-PR. These innovative strategies aim to address the challenges and pressures associated with energy and environmental issues, particularly by enhancing artificial photosynthesis efficiency.
Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field. Here using surface-enhanced infrared absorption (SEIRA) spectroscopy, attenuated total reflection (ATR) spectroscopy and molecular dynamics (MD), we reveal the assembled CN at gold nanofilm exhibits a reduced Stark tuning rate (STR) referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au. These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.
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