Fabrication of PεCL-AuNP-BSA core-shell-corona nanoparticles for flexible spatiotemporal drug delivery and SERS detection.

Nanoparticles with protein coronae can be used as promising multifunctional platforms for nanomedicine due to the possibility of performing surface functionalization on protein molecules and the achievement of biomedical properties. In this research, nanoparticles (NPs) with poly(ε-caprolactone) (PεCL) cores, gold NP (AuNP) shells and BSA coronae were fabricated by a self-assembly approach. The hydrophobic PεCL cores were used to encapsulate curcumin (CUR), the AuNP shells were decorated with a Raman probe, and the protein molecules in the coronae were functionalized with folic acid (FA). The self-assembly behaviors, drug delivery and the surface-enhanced Raman scattering (SERS) effect of the hybrid NPs were investigated in this research. The sizes of the core-shell-corona NPs (CSCNPs) are dependent on the initial concentrations of PεCL and AuNPs. The CUR in CSCNPs show enzyme-triggered release properties. The added lipase or trypsin can facilitate the CUR release from the hybrid NPs. The functionalization of CSCNPs with FA can significantly improve the internalization of NPs into 4T1 tumor cells due to the overexpressed folate receptors on the cells. In addition, the SERS effect of CSCNPs can be achieved when the AuNPs are decorated with 2-naphthalenethiol. The hybrid CSCNPs can be used as a promising platform for spatiotemporal drug delivery, cell imaging, and theranostics. Based on the same CSCNP platform, flexible functions can be adjusted according to the application needs.

Star-shaped poly(2-aminoethyl methacrylate)s as non-viral gene carriers: Exploring structure-function relationship.

Gene therapy shows much promise in treating many inheritable and acquired diseases, but challenges remain in the design of gene vectors with low cytotoxicity and high transfection efficiency. Elucidating the structure-function relationship of non-viral polymer-based gene carriers is crucial for improving the design and performance of safe and effective gene therapy approaches. The cationic poly(2-aminoethyl methacrylate) (PAEM) containing primary amino side groups is an attractive carrier for gene delivery. This study focuses on four PAEM-based polycations with well-defined molecular weight and chain architecture. The polymers include three cyclodextrin (CD)-cored star-shaped PAEM polycations (s-PAEM), synthesized by atom transfer radical polymerization (ATRP), and a linear PAEM polycation (l-PAEM), synthesized via activators regenerated by electron transfer (ARGET) ATRP. All four polycations could condense plasmid DNA (pDNA) into spherical polyplexes with small sizes (<200 nm). The polyplexes showed excellent stability during storage and were able to resist electrostatic destabilization. The cytotoxicity of these polycations was depended on dose and target cell type and was influenced by molecular weight and chain architecture, yet the polyplexes showed little cytotoxicity regardless of the type of polymer used. The transfection efficiency of PAEM polycations was highly dependent upon molecular weight, molecular architecture (star versus linear) and target cell type. In most cases, polyplexes formed by high-molecular-weight s-PAEM performed the best. Moreover, at a specific N/P ratio, the transfection efficiency mediated by s-PAEM was higher in MCF-7 breast cancer cells than in COS-7 fibroblast-like cells, but such cell-type dependence was not obvious for l-PAEM. These findings indicate that the star-shaped PAEM polycations could be promising gene carriers for gene therapy applications.

External temperature control of lymphatic drainage of thermo-sensitive nanomaterials.

Nano-carrier-facilitated delivery of bioactive molecules into lymph nodes (LNs) has found application in the treatment and diagnosis of numerous immune-related diseases. Much work has focused on optimization of physicochemical properties of the nano-carrier to enhance lymphatic drainage passively, whereas active modulation of the quantity and timing of lymphatic delivery remains a significant challenge. Here, inspired by the success of thermo-modulation of tumor targeting, we have developed a simple external temperature control strategy to regulate the distribution of thermo-sensitive nanomaterials between the injection site and draining LNs. To demonstrate feasibility of this strategy, we injected Rhodamine-B-labeled poly(N-isopropylacrylamide) (RhB-PNIPAm) (2.5 kDa) into the footpad of mice at different initial temperatures - either below or above the lower critical solution temperature (LCST), followed by physical cooling of the injection site. We show that RhB-PNIPAm drained efficiently into the popliteal and inguinal nodes (pLNs, iLNs, respectively) with low levels of accumulation in major internal organs. Within the first two hours post-injection the rate of drainage was primarily dependent on the initial temperature of RhB-PNIPAm. However, over the course of 24 h, temperature gradient due to local cooling affected significantly the draining of the injection site, resulting in differential accumulation of RhB-PNIPAm in the proximal (pLNs) versus the distal (iLNs) nodes. This study provides a new methodology and insights for modulating in vivo lymphatic distribution of thermo-sensitive nanomaterials with implications in immune regulation and immunotherapy.

Multi-stimuli-responsive biohybrid nanoparticles with cross-linked albumin coronae self-assembled by a polymer-protein biodynamer.

A thermoresponsive polymer-protein biodynamer was prepared via the bioconjugation of an aliphatic aldehyde-functionalized copolymer to hydrazine-modified bovine serum albumin (BSA) through reversible pyridylhydrazone linkages. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography (SEC) results indicated that the pyridylhydrazone linkages cleaved in an intracellular-mimicking acidic milieu, thus leading to the release of BSA. The dynamic character of the protein biodynamer was demonstrated by exchange reactions with aldehyde-containing molecules. The biodynamer self-assembled into spherical micelles at a temperature above its lower critical solution temperature (LCST). Subsequently, BSA molecules within the hydrophilic coronae of the micelles were readily cross-linked via reaction with cystamine at 45°C, and multi-stimuli-responsive nanoparticles were generated. The biohybrid nanoparticles reversibly swelled and shrank as the cores of the nanoparticles were solvated below the LCST and desolvated above the LCST. The accessible reversibility of the pyridylhydrazone bonds imparts pH-responsive and dynamic characteristics to the nanoparticles. The nanoparticles displayed glutathione (GSH) responsiveness, and the synergistic effects of pH and GSH resulted in complete disintegration of the nanoparticles under the intracellular-mimicking acidic and reductive conditions. The nanoparticles were also enzyme-responsive and disintegrated rapidly in the presence of protease. In vitro cytotoxicity and cell uptake assays demonstrated that the nanoparticles were highly biocompatible and effectively internalized by HepG2 cells, which make them interesting candidates as vehicles for drug delivery application and biomimetic platforms to investigate the biological process in nature. SIGNIFICANCE STATEMENT: In this research, we report the synthesis of a temperature and pH dual-responsive polymer-protein biodynamer through reversible pyridylhydrazone formation. The prepared biodynamer can offer a potential platform for intracellular protein delivery. The multi-stimuli-responsive biohybrid nanoparticles containing disulfide functionalities are constructed by cross-linking albumin coronae of the biodynamer micelles. With the combination of a thermoresponsive polymer, protein and reversible covalent bonds, the biohybrid nanoparticles are endowed with highly biocompatible, environmentally responsive and adaptive features. These nanoparticles present the ability to undergo changes in their constitution, hydrodynamic size and nanostructure in response to physical, chemical and biological stimuli, which make them interesting candidates as vehicles for drug delivery application and a biomimetic platform to investigate the biological process in nature.

Polymers for DNA Vaccine Delivery.

DNA vaccine is a third generation vaccine type based on concepts and techniques of molecular biology. It can closely mimic live infections and induce both antibody and cell mediated immune responses and thus has much potential for treating chronic viral infection and cancer. How do we transport the DNA vaccine to the right target cells in lymphoid tissues and organs? How do we achieve high and robust gene transfection efficiency while simultaneously inducing DC maturation and antigen presentation? These questions pose significant challenges and addressing them may require serious efforts in developing better biomaterials as carriers. This review is dedicated to the discussion of polymers as nanoscale carriers for the DNA vaccine. We summarize recent advances in polymer science and engineering to overcome multilevel hurdles for DNA vaccine delivery and conclude with thoughts on challenges and opportunities that may shape the future of polymers in DNA vaccination.

In situ fabrication of PHEMA-BSA core-corona biohybrid particles.

Polymer-protein core-corona particles can be used as multifunctional platforms in biological and medical applications. In this research, we prepared poly(2-hydroxyethyl methacrylate)-bovine serum albumin (PHEMA-BSA) core-corona particles by the "grafting from" method. In order to prepare the particles, activators generated by electron transfer for atom transfer radical polymerizations (AGET ATRP) of HEMA initiated by a BSA macroinitiator were performed. The polymerizations were conducted in the presence of ppm amounts of transition metal catalyst and ascorbic acid. Transmission electron microscopy, atomic force microscopy, dynamic light scattering and ξ-potential measurements were used to characterize the core-corona particles. The average size and ξ-potentials of the particles are strongly dependent on the amounts of BSA used in AGET ATRP. The secondary structure and bioactivity of the protein molecules in the coronae of the particles were studied. In vitro cytotoxicity assays and cell uptake assays indicate that the biohybrid particles are nontoxic and can be internalized into the cells. The polymer-protein core-corona particles will find applications in drug delivery and biomedical imaging.