Two-photon AgNP/DNA-TP dye nanosensing conjugate for biothiol probing in live cells

Functional Nucleic Acid Probes Based on Two-Photon for Biosensing

Functional nucleic acid (FNA) probes have been widely used in environmental monitoring, food analysis, clinical diagnosis, and biological imaging because of their easy synthesis, functional modification, flexible design, and stable properties. However, most FNA probes are designed based on one-photon (OP) in the ultraviolet or visible regions, and the effectiveness of these OP-based FNA probes may be hindered by certain factors, such as their potential for photodamage and limited light tissue penetration. Two-photon (TP) is characterized by the nonlinear absorption of two relatively low-energy photons of near-infrared (NIR) light with the resulting emission of high-energy ultraviolet or visible light. TP-based FNA probes have excellent properties, including lower tissue self-absorption and autofluorescence, reduced photodamage and photobleaching, and higher spatial resolution, making them more advantageous than the conventional OP-based FNA probes in biomedical sensing. In this review, we summarize the recent advances of TP-excited and -activated FNA probes and detail their applications in biomolecular detection. In addition, we also share our views on the highlights and limitations of TP-based FNA probes. The ultimate goal is to provide design approaches for the development of high-performance TP-based FNA probes, thereby promoting their biological applications.

Use of metal nanoparticles for preconcentration and analysis of biological thiols

Metal nanoparticles (NPs) exhibit several unique physicochemical properties, including redox activity, surface plasmon resonance, ability to quench fluorescence, biocompatibility, or a high surface-to-volume ratio. They are being increasingly used in analysis and preconcentration of thiol containing compounds, because they are able to spontaneously form a stable Au/Ag/Cu-S dative bond. They thus find wide application in environmental and particularly in medical science, especially in the analysis of biological thiols, the endogenous compounds that play a significant role in many biological systems. In this review article, we provide an overview of various types of NPs that have been applied in analysis and preconcentration of biological thiols, mainly in human biological fluids. We first discuss shortly the types of NPs and their synthesis, properties, and their ability to interact with thiol compounds. Then we outline the sample preconcentration and analysis methods that were used for this purpose with special emphasis on optical, electrochemical, and separation techniques.

Water soluble fluorophore-carbazole–Au–DNA nanohybrid: enhanced two-photon absorption for living cell imaging application

Water soluble L–Au–DNA nanohybrid exhibits enhanced 2PA properties that can widely and evenly uptake into the lysosome of HepG2 cells.

A novel AgNP/DNA/TPdye conjugate-based two-photon nanoprobe for GSH imaging in cell apoptosis of cancer tissue

By combining DNA with a two-photon dye (TPdye) and silver nanoparticles (AgNPs), a novel two-photon nanoprobe for glutathione (GSH) imaging in cell apoptosis of cancer tissue was designed in the present study.