In this paper, a novel thermally-reduced carbon dot (t-CD) based fluorescence resonance energy transfer (FRET) sensor for the determination of vitamin B₁₂ (VB₁₂) in aqueous solutions is reported. Carbon dots (CDs) have attracted great attention due to their excellent tunable optical properties, low cost, easy fabrication and low toxicity, which make them ideal candidates for optical sensors. Through esterification reactions, blue luminescent t-CDs were prepared by the carbonization of citric acid and thermally reduced by a thermogravimetric analyzer. After thermal reduction, the quantum yield of the t-CDs demonstrated a 5-fold increase, which makes t-CDs excellent donors in the FRET process. The t-CDs were used to detect VB₁₂ with concentrations ranging from 1 to 12 μg ml⁻¹ and their limit of detection (LOD) was as low as 0.1 μg ml⁻¹. The as-synthesized t-CD based optical probing technique is demonstrated to be simple, cost-effective, sensitive and selective for the detection of biologically significant VB₁₂.

A super tough hydrogel with tunable mechanical properties was 3D printed.

Current clinical treatments including surgical resection, radiation therapy and chemotherapy for brain cancer result in high mortality due to the complex structure of the brain aggressiveness of brain cancer. Recently, non-invasive photothermal therapy (PTT) using near infrared laser irradiation has been developed as an alternative emerging therapy for brain cancer. In this paper, a biocompatible porphyrin functionalized graphene oxide (PGO) with high absorbance at 808 nm is synthesized as a photothermal platform for brain cancer therapy. Graphite oxide is exfoliated and conjugated with porphyrin through π–π interactions. This PGO is two times more stable than reduced graphene oxide (rGO) in aqueous solution. Most importantly, the efficiency of the photo-thermal conversion of PGO is increased by 89% and 33% compared to graphene oxide and rGO under 808 nm laser irradiation, causing ablation of a large number of brain cancer cells in vitro. This PGO platform containing active functional groups allows specific targeting in PTT without harming healthy cells and tissues.