Ultrasmall metal nanoclusters (NCs, <2 nm) have emerged as a novel class of luminescent probes due to their atomically precise size and tailored physicochemical properties. The rapid advancements in the design and utilization of metal NC-based luminescent probes are facilitated by the atomic-level manipulation of metal NCs. This review article explores (i) the engineering of metal NCs' functions for bioimaging applications, and (ii) the diverse uses of metal NCs in bioimaging. We begin by presenting an overview of the engineering functions of metal NCs as luminescent probes for bioimaging applications, highlighting key strategies for enhancing NCs' luminescence, biocompatibility and targeting capabilities towards biological specimens. Our discussion then centers on the bioimaging applications of metal NCs in subcellular organelles, individual cells, tissues, and entire organs. Finally, we offer a perspective on the challenges and potential developments in the future use of metal NCs for bioimaging applications.
Being abundant in many tropical part of the world, Dioscorea sp. as food is limited due to its toxicity. However polysaccharides derive from these tubers could be important for other applications. Here we developed a Highly Luminescent Carbon Nanodots (C-dots) via acid hydrolysis of Gadong starch (GS). The hydrolysis rate of GS increased from 49% to 86% within 7 days while the X-ray diffraction showed the native GS particle is a C-crystalline type. The GS particles were either round or oval with diameters ranging from 50-90 nm. Further acid dehydration and surface oxidation reduced the size of GS nanoparticles to 6-25 nm. The C-dots produced a fluorescent emission at wavelength 441 nm. Toxicity tests demonstrate that zebrafish embryo were able to tolerate the C-dots for 48 h after exposure. This study has successfully demonstrated a novel approach of converting GS into excellent fluorescent C-dot.
Chemiluminescence was evaluated as a diagnostic aid in the detection of oral cancer and potentially malignant epithelial lesions (PMELs) by comparing it against 1% tolonium chloride mouth rinse. Forty-six clinically identified lesions [14 primary squamous cell carcinoma (SCC), 26 PMELs and 6 benign lesions] and five cases of normal oral mucosa from 40 subjects (inclusive of 10 previously treated SCC cases) were examined with a commercial chemiluminescent kit (Vizilite) and tolonium chloride. Biopsy and histological verification of 31 lesions disclosed 14 SCC (45.2%), 10 epithelial dysplasias (32.3%), 5 lichen planus (16.1%) and 2 benign lesions (6.4%). For the remaining 15 lesions, a biopsy was not performed owing to patient's lack of consent or ill-health. The five cases of normal oral mucosa which tested negative for both tools were also not biopsied for ethical reasons. Sensitivity for Vizilite and tolonium chloride was 100% and 70.3%, respectively; and specificity was 14.2% for Vizilite and 25% for tolonium chloride. Their accuracy was 80.6% and 64.5%, respectively. Current findings suggest that chemiluminescence is a more reliable diagnostic tool than tolonium chloride in the detection of oral cancer and PMELs, and for follow-up of patients treated for the same.