Amphiphilic phospholipid-iodinated polymer conjugates for bioimaging.

Amphiphilic phospholipid-iodinated polymer conjugates were designed and synthesized as new macromolecular probes for a highly radiopaque and biocompatible imaging technology. Bioconjugation of PEG 2000-phospholipids and iodinated polyesters by click chemistry created amphiphilic moieties with hydrophobic polyesters and hydrophilic PEG units, which allowed their self-assemblies into vesicles or spiked vesicles. More importantly, the conjugates exhibited high radiopacity and biocompatibility in in vitro X-ray and cell viability measurements. This new type of bioimaging contrast agent with a Mn value of 11 289 g mol-1 was found to have a significant X-ray signal at 3.13 mg mL-1 of iodine equivalent than baseline and no cytotoxicity after 48 hours incubation of with HEK and 3T3 cells at 20 µM (20 picomoles) concentration of conjugates per well. The potential of adopting the described macromolecular probes for bioimaging was demonstrated, which could further promote the development of a field-friendly and highly sensitive bioimaging contrast agent for point-of-care diagnostic applications.

Design of Curcumin Loaded Carbon Nanodots Delivery System: Enhanced Bioavailability, Release Kinetics, and Anticancer Activity.

Despite the potential health benefits of curcumin, such as antioxidant, anticancer, anti-inflammatory, and antimicrobial properties, its usage is limited by poor bioavailability and low aqueous solubility. Nano-formulations of curcumin have gained a lot of attention due to their increased bioavailability, solubility, circulation times, targeted specificity, decreased biodegradation, better stability, and improved cellular uptake. The current study aimed to enhance the bioavailability of curcumin using carbon nanodots (CNDs) as loading vehicles to deliver curcumin due to their excellent biocompatibility, aqueous solubility, and photoluminescence properties. Two types of CNDs (E-CNDs and U-CNDs) were used for curcumin loading and characterized for particle size, morphology, loading capability (measured as adsorption efficiency and loading capacity), stability, photoluminescence properties, in vitro drug release studies, cellular uptake, and anticancer activity. The prepared curcumin-loading CNDs (Curc-CNDs) displayed sizes around or below 10 nm with good stability. The Curc-E-CNDs demonstrated a curcumin adsorption efficiency of 91% in solution, while the Curc-U-CNDs have an adsorption efficiency of 82%. Both have a loading capacity of 3.4-3.8% with respect to the weight of the CNDs. Curcumin release followed a controlled sustained pattern that a total of 60% and 74% of curcumin was released at 72 h from Curc-E-CNDs and Curc-U-CNDs, respectively, in pH 5 buffer, and almost 90% was released in culture media within 96 h. Both of the Curc-CNDs were uptaken by cells and exhibited prominent cytotoxicity toward cancer cells. The results clearly depict the role of CNDs as efficient carriers for curcumin delivery with prolonged release and enhanced bioavailability, thereby improving the overall antitumor activity.

Tuning the Functional Groups on Carbon Nanodots and Antioxidant Studies.

Carbon nanodots (CNDs) have shown good antioxidant capabilities by scavenging oxidant free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH•) and reactive oxygen species. While some studies suggest that the antioxidation activities associate to the proton donor role of surface active groups like carboxyl groups (⁻COOH), it is unclear how exactly the extent of oxidant scavenging potential and its related mechanisms are influenced by functional groups on CNDs' surfaces. In this work, carboxyl and the amino functional groups on CNDs' surfaces are modified to investigate the individual influence of intermolecular interactions with DPPH• free radical by UV-Vis spectroscopy and electrochemistry. The results suggest that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH•.

Plasmon-Exciton Coupling in Photosystem I Based Biohybrid Photoelectrochemical Cells.

The light-induced property of photosystem I (PSI) has been utilized to convert solar energy to electrical energy in photoelectrochemical cells. Here we provide new results on the relationship between surface plasmon generation (SPG) efficiency of nanoslits and the experimentally obtained photocurrent by immobilizing PSI on the gold nanoslit electrode surfaces regarding different nanoslit widths. The photocurrent increases with the increment of SPG efficiency. This finding can be attributed to the phenomenon of plasmon-exciton coupling effect on the PSI in the nanoslits. The enhancement of photocurrent generation is discussed on the basis of plasmonic light trapping and plasmon-induced resonance energy transfer.