RESUMEN
Low-cost analytical assays enable accessible detection of clinically and environmentally important analytes; however, common enzyme-based assays suffer from high production and storage costs. Catalytically active synthetic materials serve as replacements for natural enzymes, but development of cost-effective, highly efficient synthetic strategies remains a challenge. Here, we utilized a facile synthesis for copper bipyridine coordination polymers (CuBpyCPs) and investigated structure-function relationships to achieve optimal catalytic properties for a glucose assay. We demonstrated the manipulation of CuBpyCP morphology, resulting in nanoscale petal-like structures and microscale high-index faceted structures, and identified three pure crystal morphologies exhibiting a comparable catalytic activity (Km = 0.3-0.5 mM) to horseradish peroxidase.
RESUMEN
Achieving long-term (>3 months) colloidal stability of upconversion nanoparticles (UCNPs) in biologically relevant buffers has been a major challenge, which has severely limited practical implementation of UCNPs in bioimaging and nanomedicine applications. To address this challenge, nine unique copolymers formulations were prepared and evaluated as UCNP overcoatings. These polymers consisted of a poly(isobutylene-alt-maleic anhydride) (PIMA) backbone functionalized with different ratios and types of phosphonate anchoring groups and poly(ethylene glycol) (PEG) moieties. The syntheses were done as simple, one-pot nucleophilic addition reactions. These copolymers were subsequently coated onto NaYF4:Yb3+,Er3+ UCNPs, and colloidal stability was evaluated in 1 × PBS, 10 × PBS, and other buffers. UCNP colloidal stability improved (up to 4 months) when coated with copolymers containing greater proportions of anchoring groups and higher phosphonate valences. Furthermore, small molecules could be conjugated to these overcoated UCNPs by use of copper-free click chemistry, as was done to demonstrate suitability for sensor and bioprobe development.
