A two-step methodology for simultaneous conjugation of DNA and poly(vinylpyrrolidone) (PVP) polymer to a single carbon quantum dot (CD) is demonstrated for the first time to fabricate a pH-responsive DNA−CD−PVP hybrid hydrogel. Cross-linking in the hydrogel was achieved using CD as the common nucleus through the formation of DNA I-motif conformation at neutral to acidic pH and noncovalent interaction of PVP that infuse self-healing and shape memory properties in the hydrogel. The hydrogel is capable of loading and sustained delivery of drugs for more than 2 weeks as demonstrated using a model drug, Hemin. The quenching of fluorescence of CD by Hemin was trackable even through simple visual monitoring, which showed that Hemin can diffuse from the loaded part to the unloaded part of the hydrogel during the self-healing process. Most significantly, the chosen CD generates reactive oxygen species (ROS) upon visible light irradiation, armoring the hydrogel with worthy antimicrobial activity. Biocompatibility of the DNA−CD−PVP hydrogel was established on human fibroblast cells, indicating their potential use in biomedical area pertaining to wound healing.

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Hollow microshells are being fabricated for potential use as versatile sensors for real-time measurements of biochemicals. These shells are assembled using Layer-by-Layer (LBL) assembly of polyions onto colloidal polymer template particles. The latex particles are subsequently dissolved leaving behind stable, hollow shells into which analyte-sensitive and reference dyes are introduced. Fundamental studies have been performed to determine optical and chemical characteristics of these shells. Tests have been performed to determine the integrity of shells with respect to leaching and structural stability and robustness. The microshells were then loaded with an assay composed of a sodium sensitive fluorophore (SBFI) or a potassium sensitive fluorophore (PBFI), along with an analyte insensitive reference dye. It has been shown that the dye-loaded capsules retain their sensitivity to ion concentration with fluorescence characteristics similar to those of the dyes in liquid-phase, and that the sensor response to increasing ion concentration is linear over a physiologically significant range. In addition, preliminary results have demonstrated the ability of these capsules to be "loaded" with other sensor chemistry, including Ruthenium/Glucose-oxidase, and a FITCdextran/TRITC-ConA competitive binding assay for glucose sensing based on fluorescent resonance energy transfer (FRET) methods.