Fluorescent ABC-Triblock Polymer Nanocarrier for Cisplatin Delivery to Cancer Cells

Genetically engineered virus-like particle-armoured and multibranched DNA scaffold-corbelled ultra-sensitive hierarchical hybridization chain reaction for targeting-enhanced imaging in living biosystems under spatiotemporal light powering

Although nucleic acids-based fluorescent biosensors, exemplified by the hybridization chain reaction (HCR), have exhibited promise as an imaging tool for detecting disease-related biomolecular makers in living biosystems, they still face certain challenges. These include the need for improved sensitivity, poor bio-targeting capability, the absence of signal enrichment interface and the uncontrollable biosensing initiation. Herein, we present a range of effective solutions. First, a stacking design resembling building blocks is used to construct a special hierarchical HCR (termed H-HCR), for which a hierarchical bridge is employed to graft multiunit HCR products. Furthermore, the H-HCR components are encapsulated into a virus-like particle (VLP) endowed with a naturally peptide-mediated targeting unit through genetic engineering of plasmids, after which the biosensor can specifically identify cancer cytomembranes. By further creating a multibranched DNA scaffold to enrich the H-HCR produced detection signals, the biosensor's analyte recognition module is inserted with a photocleavage-linker, allowing that the biosensing process can be spatiotemporally initiated via a light-powered behavior. Following these innovations, this genetically engineered VLP-armoured and multibranched DNA-scaffold-corbelled H-HCR demonstrates an ultra-sensitive and specific biosensing performance to a cancer-associated microRNA marker (miRNA-155). Beyond the worthy in vitro analysis, our method is also effective in performing imaging assays for such low-abundance analyte in living cells and even bodies, thus providing a roust platform for disease diagnosis.

Structural Engineering of Star Block Biodegradable Polymer Unimolecular Micelles for Drug Delivery in Cancer Cells

The present investigation reports the structural engineering of biodegradable star block polycaprolactone (PCL) to tailor-make aggregated micelles and unimolecular micelles to study their effect on drug delivery aspects in cancer cell lines. Fully PCL-based star block copolymers were designed by varying the arm numbers from two to eight while keeping the arm length constant throughout. Multifunctional initiators were exploited for stepwise solvent-free melt ring-opening polymerization of ε-caprolactone and γ-substituted caprolactone to construct star block copolymers having a PCL hydrophobic core and a carboxylic PCL hydrophilic shell, respectively. A higher arm number and a higher degree of branching in star polymers facilitated the formation of unimolecular micelles as opposed to the formation of conventional multimicellar aggregates in lower arm analogues. The dense core of the unimolecular micelles enabled them to load high amounts of the anticancer drug doxorubicin (DOX, ∼12-15%) compared to the aggregated micelles (∼3-4%). The star unimolecular micelle completely degraded leading to 90% release of the loaded drug upon treatment with the lysosomal esterase enzyme in vitro. The anticancer efficacies of these DOX-loaded unimolecular micelles were tested in a breast cancer cell line (MCF-7), and their IC₅₀ values were found to be much lower compared to those of aggregated micelles. Time-dependent cellular uptake studies by confocal microscopy revealed that unimolecular micelles were readily taken up by the cells, and enhancement of the drug concentration was observed at the intracellular level up to 36 h. The present work opens new synthetic strategies for building a next-generation biodegradable unimolecular micellar nanoplatform for drug delivery in cancer research.