Functionalizable Amine-Based Polymer Nanoparticles

Surface functionalization of nanoparticles and host–guest properties of nanoassemblies are two critical features in the utilization of nanostructures in a variety of applications in materials, chemical, and biological nanotechnology. However, simultaneously incorporating these two features in one nanoparticle design is a rather challenging task. We have developed a simple and versatile nanoparticle platform that addresses this challenge. We have designed and characterized a polymer nanoparticle that provides the ability to encapsulate hydrophobic guest molecules and surface functionalization with a wide range of functional groups. In addition, we have also demonstrated a new and simple approach to tune the size of the nanoparticles

Activatable Dendritic ¹⁹F Probes for Enzyme Detection

We describe a novel activatable probe for fluorine-19 NMR based on self-assembling amphiphilic dendrons. The dendron probe has been designed to be spectroscopically silent due to the formation of large aggregates. Upon exposure to the specific target enzyme, the aggregates disassemble to give rise to a sharp ¹⁹F NMR signal. The probe is capable of detecting enzyme concentrations in the low nanomolar range. Response time of the probe was found to be affected by the hydrophilic–lipophilic balance of dendrons. Understanding the structural factors that underlie this design principle provides the pathway for using this strategy for a broad range of enzyme-based imaging

Ligand-Decorated Nanogels: Fast One-Pot Synthesis and Cellular Targeting

Nanoscale vehicles for delivery have been of interest and extensively studied for two decades. However, the encapsulation stability of hydrophobic drug molecules in delivery vehicles and selective targeting these vehicles into disease cells are potential hurdles for efficient delivery systems. Here we demonstrate a simple and fast synthetic protocol of nanogels that shows high encapsulation stabilities. These nanogels can also be modified with various targeting ligands for active targeting. We show that the targeting nanogels (T-NGs), which are prepared within 2 h by a one-pot synthesis, exhibit very narrow size distributions and have the versatility of surface modification with cysteine-modified ligands including folic acid, cyclic arginine-glycine-aspartic acid (<i>c</i>RGD) peptide, and cell-penetrating peptide. T-NGs hold their payloads, undergo facilitated cell internalization by receptor-mediated uptake, and release their drug content inside cells due to the reducing intracellular environment. Selective cytotoxicity to cells, which have complementary receptors, is also demonstrated

Facile Preparation of Nanogels Using Activated Ester Containing Polymers

A facile methodology to prepare water-dispersible nanogels based on pentafluorophenyl acrylate and polyethylene glycol methacrylate random copolymer and diamine cross-linkers has been developed. The cross-linking reaction was characterized by FTIR and ¹⁹F NMR. We show that those nanogels are (<i>i</i>) water-dispersible; (<i>ii</i>) can conveniently encapsulate lipophilic guest molecules; (<i>iii</i>) can be prepared with different nanosizes; and (<i>iv</i>) are engineered to allow for surface decoration with additional functional groups

Protein AND Enzyme Gated Supramolecular Disassembly

An amphiphilic nanoassembly was designed to respond to the concurrent presence of a protein and an enzyme. We present herein a system, where in the presence of these two stimuli supramolecular disassembly and molecular release occur. This molecular release arises in the form a fluorescence response that has been shown to be specific. We also show that this system can be modified to respond only if light stimulus is also present in addition to the protein and the enzyme. Demonstration of such supramolecular disassembly principles could have broad implications in a variety of biological applications

Influence of Charge Density on Host–Guest Interactions within Amphiphilic Polymer Assemblies in Apolar Media

The effects of charge density on supramolecular host–guest interactions between peptides and reverse micelles are studied using an amphiphilic random copolymer scaffold. While our classical understanding of polyvalent electrostatic interactions suggests that the binding capacity should increase with charge density, our results indicate that this correlation does not necessarily hold within the nanoscale environment of reverse micelles. Using four series of different polymers, we show that peptide binding efficiency depends on the presence of an optimum charge density inside the reverse micelles. Interestingly, the distribution of charges does not have a significant effect on binding. Reverse micelle stability at high charge densities can be regained by tuning the hydrophilic–lipophilic balance of the polymer, yet an optimal density dependence remains. Our findings improve our understanding of host–guest chemistry in confined aqueous environments

Templated Self-Assembly of a Covalent Polymer Network for Intracellular Protein Delivery and Traceless Release

Trafficking proteins inside cells is an emerging field with potential utility in basic cell biology and biological therapeutics. A robust and sustainable delivery strategy demands not only good protection of the cargo but also reversibility in conjugation and activity. We report a protein-templated polymer self-assembly strategy for forming a sheath around the proteins and then tracelessly releasing them in the cytosol. The versatility of the approach, demonstrated here, suggests that the strategy is compatible with a wide array of biologics

Biodistribution Analysis of NIR-Labeled Nanogels Using <i>in Vivo</i> FMT Imaging in Triple Negative Human Mammary Carcinoma Models

The purpose of this study is to evaluate the biodistribution properties of random-copolymer-based core-cross-linked nanogels of various sizes and surface poly­(ethylene glycol) composition. Systematic variations of near-IR labeled nanogels, comprising varying particle sizes (28–135 nm), PEG corona quantity (0–50 mol %), and PEG length (PEG <i>M</i>_n 1000, 2000, and 5000), were prepared and injected in mice that had been subcutaneously implanted with MDA-MB-231-luc-D3H2LN human mammary carcinoma. <i>In vivo</i> biodistribution was obtained using fluorescence molecular tomography imaging at 0, 6, 24, 48, and 72 h postinjection. Retention of total body probe and percentages of total injected dose in the tumor, liver, spleen, lungs, heart, intestines, and kidneys were obtained. Smaller nanogels (∼30–40 nm) with a high PEG conjugation (∼43–46 mol %) of <i>M</i>_n 2000 on their coronas achieved the highest tumor specificity with peak maximum 27% ID/g, a statistically significant propensity toward accumulation with 16.5% ID/g increase from 0 to 72 h of imaging, which constitutes a 1.5-fold increase. Nanogels with greater tumor localization also had greater retention of total body probe over 72 h. Nanogels without extensive PEGylation were rapidly excreted, even at similar sizes to PEGylated nanogels exhibiting whole body retention. Of all tissues, the liver had the highest % ID, however, like other tissues, it displayed a monotonic decrease over time, suggesting nanogel clearance by hepatic metabolism. <i>Ex vivo</i> quantification of individual tissues from gross necropsy at 72 h postinjection generally correlated with the FMT analysis, providing confidence in tissue signal segmentation <i>in vivo</i>. The parameters determined to most significantly direct a nanogel to the desired tumor target can lead to improve effectiveness for nanogels as therapeutic delivery vehicles

Multi-Stimuli-Responsive Amphiphilic Assemblies through Simple Postpolymerization Modifications

A strategy to construct different stimuli-responsive polymers from postpolymerization modifications of a single polymer scaffold via thiol–disulfide exchange has been developed. Here, we report on a random copolymer that enables the design and syntheses of a series of dual or multi-stimuli-responsive nanoassemblies using a simple postpolymerization modification step. The reactive functional group involves a side chain monopyridyl disulfide unit, which rapidly and quantitatively reacts with various thiols under mild conditions. Independent and concurrent incorporation of physical, chemical, or biologically responsive properties have been demonstrated. We envision that this strategy may open up opportunities to simplify the synthesis of multifunctional polymers with broad implications in a variety of biological applications

Supramolecular Assemblies for Transporting Proteins Across an Immiscible Solvent Interface

Polymeric supramolecular assemblies that can effectively transport proteins across an incompatible solvent interface are described. We show that electrostatics and ligand–protein interactions can be used to selectively transport proteins from an aqueous phase to organic phase. These transported proteins have been shown to maintain their tertiary structure and function. This approach opens up new possibilities for application of supramolecular assemblies in sensing, diagnostics and catalysis