Carbon dots (CDs) are a class of carbon-based nanomaterials undergoing rapid development with broad potential applications across diverse biomedical fields. These materials are highly attractive for diagnostics, therapeutics, and nanomedicine due to their remarkable optical and physicochemical properties, including photoluminescence, biocompatibility, and aqueous dispersibility. CDs can be synthesized using various techniques, ranging from top-down to bottom-up approaches. Among these, biogenic synthesis, utilizing natural sources and waste materials, presents an eco-friendly and sustainable alternative. CDs have exhibited considerable promise in diagnostics, especially with bioimaging and biosensing, providing both high sensitivity and precise identification. CDs are presently being investigated in the pharmaceutical sector for their potential applications in cancer and infection treatment, as well as in photodynamic and thermal therapies. The advancement of CD composites, through enhanced functionality and broader application, facilitates novel research in nanomedicine. This article highlights the advantages of CDs, focusing on their structural properties, classification, and versatility in synthesis methods. Furthermore, the safety and toxicity profiles of CDs are critically analyzed. In conclusion, the innocuity, adaptability, and multifunctionality of CDs position them as a cornerstone in the advancement of nanotechnology and biomedical applications. With their broad applicability and promising potential, CDs stand poised to drive significant innovation across diagnostics, therapeutics, and other domains, heralding a new era in nanomedicine and sustainable material development.

Gold nanorods (GNRs) are ideal choice in biomedical research due to their amenability of synthesis, tunable plasmonic properties, less toxicity and ease of detection but their diverse biological applications necessitate stable structure. Despite two decades' efforts made towards reproducible anisotropic structures synthesis, still the kinetic control during GNRs growth has not been achieved. This study is an attempt to apprehend thermodynamic and kinetic parameters for synthesising mono‐disperse, reproducible and highly stable GNRs with desired aspect ratios. Effects of various growth parameters and assay steps on the facile and reproducible synthesis of GNRs are analysed. GNRs' environmental and biological colloidal stability is studied through UV–Vis spectroscopy based particle instability parameter (PIP < 0.1). The authors hereby report GNRs with tunable longitudinal surface plasmon resonance (682–906 nm) having different aspect ratios (2.5–4.6) that are stable at 28–60°C; however, prolonged high temperature ( > 60°C) and alkaline pH can trigger colloidal instability. GNRs remain stable at higher salt concentration, physiological and slightly acidic pH. GNRs can be stored in 0.001 M cetyltrimethylammonium bromide for 3 months without compromising their stability. PEGylated GNRs are quite stable in cellular media solution (PIP < 0.1). With current optimised growth conditions, no aggregation at physiological pH and stability at high temperatures make GNRs an ideal candidate in biomedical applications.

Two of the limitations associated with cancer treatment are the low efficacy and the high dose-related side effects of anticancer drugs. The purpose of the current study was to fabricate biocompatible multifunctional drug-loaded nanoscale moieties for co-therapy (chemo-photothermal therapy) with maximum efficacy and minimum side effects. Herein, we report in vitro anticancerous effects of doxorubicin (DOX) loaded on gold nanorods coated with the polyelectrolyte poly(sodium-4-styrenesulfonate) (PSS-GNRs) with and without NIR laser (808 nm, power density = 1.5 W/cm² for 2 min) irradiation. The drug-loading capacity of PSS-GNRs was about 76% with a drug loading content of 3.2 mg DOX/mL. The cumulative DOX release significantly increased after laser exposure compared to non-irradiated samples (p < 0.05). The zeta potential values of GNRs, PSS-GNRs and DOX-PSS-GNRs were measured as 42 ± 0.1 mV, −40 ± 0.3 mV and 39.3 ± 0.6 mV, respectively. PSS-GNRs nanocomplexes were found to be biocompatible and showed higher photothermal stability. The DOX-conjugated nanocomplexes with NIR laser irradiation appear more efficient in cell inhibition (93%) than those without laser exposure (65%) and doxorubicin alone (84%). The IC₅₀ values of PSS-GNRs-DOX and PSS-GNRs-DOX were measured as 7.99 and 3.12 µg/mL, respectively, with laser irradiation. Thus, a combinatorial approach based on chemotherapy and photothermal strategies appears to be a promising platform in cancer management.