Carbon dots (C-dots) are one of the most highlighted carbon-based materials for biological applications such as delivery of therapeutic payloads for cancer treatment mainly due to their biocompatibility and unique optical properties. In this work, we have explored the drug carrying capacity of highly fluorescent sorbitol-derived C-dots for targeted delivery of doxorubicin (DOX). We have used folic acid (FA) as a navigational molecule due to its high expression in most cancer cells. Before attachment of the DOX, the surfaces of the C-dots were protected with bovine serum albumin (BSA) to make them more biocompatible and able to hold a high amount of drugs. The release profile of DOX was studied using standard statistical models and confirmed to be first order at pH 7.2. Cellular imaging was performed using epifluorescence microscopy, which showed bright green coloured fluorescence due to internalization of C-dots specifically targeted with FA in HeLa cells.

A novel report on microwave assisted synthesis of bright carbon dots (C-dots) using gum arabic (GA) and its use as molecular vehicle to ferry ciprofloxacin hydrochloride, a broad spectrum antibiotic, is reported in the present work. Density gradient centrifugation (DGC) was used to separate different types of C-dots. After careful analysis of the fractions obtained after centrifugation, ciprofloxacin was attached to synthesize ciprofloxacin conjugated with C-dots (Cipro@C-dots conjugate). Release of ciprofloxacin was found to be extremely regulated under physiological conditions. Cipro@C-dots were found to be biocompatible on Vero cells as compared to free ciprofloxacin (1.2 mM) even at very high concentrations. Bare C-dots (∼13 mg mL⁻¹) were used for microbial imaging of the simplest eukaryotic model—Saccharomyces cerevisiae (yeast). Bright green fluorescent was obtained when live imaging was performed to view yeast cells under fluorescent microscope suggesting C-dots incorporation inside the cells. Cipro@C-dots conjugate also showed enhanced antimicrobial activity against both model gram positive and gram negative microorganisms. Thus, the Cipro@C-dots conjugate paves not only a way for bioimaging but also an efficient new nanocarrier for controlled drug release with high antimicrobial activity, thereby serving potential tool for theranostics.

Carbon dots (C-dots) are novel nanomaterials for biological applications owing to their inherent surface decoration by a variety of functional groups, excellent fluorescent properties and biocompatibility under physiological conditions. Gold nanorods (GNRs) are one of the most celebrated nanomaterials for photothermal therapy as well as delivery of therapeutic payloads because of their typical size and shape related features. We have synthesized a unique blend of C-dots and GNRs (C-dots@GNRs) for the controlled release of doxorubicin (DOX) under ideal physiological conditions. Highly fluorescent C-dots were synthesized using microwave assisted heating of gum arabic (GA) and subsequently purified using Sucrose Density Gradient Centrifugation (SDGC). In a modified seed mediated protocol, purified C-dots were added into the growth solution, to make a C-dots@GNR complex. This complex was used for anchoring DOX via covalent and non-covalent pH sensitive chemical bonds. Under physiological conditions, the drug loading capacity of C-dots@GNRs was calculated to be ∼94%. Another beneficial attribute of the complex was found to be synergistic potential in high drug loading and rapid burst of drug release under the influence of near infrared (NIR) radiation (808 nm), thus proving a highly biocompatible thermo–chemotherapy for solid tumors.

The use of phenylalanine derived non-toxic carbon dots (C-dots) as a vehicle for the delivery of widely used anti-psychotic drug haloperidol (HaLO) is described in the present research work. The C-dots were found to have remarkable optical properties and to exhibit bright green fluorescence under UV light (λ_ex = 365 nm). The UV-Vis spectrum of the C-dots exhibits peaks at 232 and 276 nm confirming their synthesis in solution. The size of the C-dots was found to be in the range of 5–10 nm, as confirmed by Field Emission Scanning Electron Microscopy (FE-SEM). Cysteamine hydrochloride (CysHCl) was used as a non-toxic linker to functionalize the purified C-dots before grafting HaLO on the surface to facilitate the controlled release under physiological conditions. A constant release of HaLO was achieved for more than 40 h, which followed the Hixson–Crowell model under standardized conditions. The C-dot–CysHCl–HaLO conjugate was found to have a much higher compatibility with MDCK cells at pH 7.2 in comparison to bare HaLO.