Chitosan Micro-Membranes with Integrated Gold Nanoparticles as an LSPR-Based Sensing Platform

Fiber Optic Localized Surface Plasmon Resonance Sensor Based on Carboxymethylated Dextran Modified Gold Nanoparticles Surface for High Mobility Group Box 1 (HMGB1) Analysis

Rapid, sensitive, and reliable detection of high mobility group box 1 (HMGB1) is essential for medical and diagnostic applications due to its important role as a biomarker of chronic inflammation. Here, we report a facile method for the detection of HMGB1 using carboxymethyl dextran (CM-dextran) as a bridge molecule modified on the surface of gold nanoparticles combined with a fiber optic localized surface plasmon resonance (FOLSPR) biosensor. Under optimal conditions, the results showed that the FOLSPR sensor detected HMGB1 with a wide linear range (10^-10 to 10^-6 g/mL), fast response (less than 10 min), and a low detection limit of 43.4 pg/mL (1.7 pM) and high correlation coefficient values (>0.9928). Furthermore, the accurate quantification and reliable validation of kinetic binding events measured by the currently working biosensors are comparable to surface plasmon resonance sensing systems, providing new insights into direct biomarker detection for clinical applications.

Exploring Low-Power Single-Pulsed Laser-Triggered Two-Photon Photodynamic/Photothermal Combination Therapy Using a Gold Nanostar/Graphene Quantum Dot Nanohybrid

Combined photodynamic/photothermal therapy (PDT/PTT) has emerged as a promising cancer treatment modality due to its potential synergistic effects and identical treatment procedures. However, its clinical application is hindered by long treatment times and complicated treatment operations when separate illumination sources are required. Here, we present the development of a new nanohybrid comprising thiolated chitosan-coated gold nanostars (AuNS-TCS) as the photothermal agent and riboflavin-conjugated N,S-doped graphene quantum dot (Rf-N,S-GQD) as the two-photon photosensitizer (TP-PS). The nanohybrid demonstrated combined TP-PDT/PTT when a low-power, single-pulsed laser irradiation was applied, and the localized surface plasmon resonance of AuNS was in resonance with the TP-absorption wavelength of Rf-N,S-GQD. The TCS coating significantly enhanced the colloidal stability of AuNSs while providing a suitable substrate to electrostatically anchor negatively charged Rf-N,S-GQDs. The plasmon-enhanced singlet oxygen (¹O₂) generation effect led to boosted ¹O₂ production both extracellularly and intracellularly. Notably, the combined TP-PDT/PTT exhibited significantly improved phototherapeutic outcomes compared to individual strategies against 2D monolayer cells and 3D multicellular tumor spheroids. Overall, this study reveals a successful single-laser-triggered, synergistic combined TP-PDT/PTT based on a plasmonic metal/QD hybrid, with potential for future investigation in clinical settings.

Recent Advances in Colorimetric Sensors Based on Gold Nanoparticles for Pathogen Detection

Infectious pathogens cause severe threats to public health due to their frightening infectivity and lethal capacity. Rapid and accurate detection of pathogens is of great significance for preventing their infection. Gold nanoparticles have drawn considerable attention in colorimetric biosensing during the past decades due to their unique physicochemical properties. Colorimetric diagnosis platforms based on functionalized AuNPs are emerging as a promising pathogen-analysis technique with the merits of high sensitivity, low-cost, and easy operation. This review summarizes the recent development in this field. We first introduce the significance of detecting pathogens and the characteristics of gold nanoparticles. Four types of colorimetric strategies, including the application of indirect target-mediated aggregation, chromogenic substrate-mediated catalytic activity, point-of-care testing (POCT) devices, and machine learning-assisted colorimetric sensor arrays, are systematically introduced. In particular, three biomolecule-functionalized AuNP-based colorimetric sensors are described in detail. Finally, we conclude by presenting our subjective views on the present challenges and some appropriate suggestions for future research directions of colorimetric sensors.