Cytosolic Delivery of Single-Chain Polymer Nanoparticles

Cytosolic delivery of therapeutic agents is key to improving their efficacy, as the therapeutics are primarily active in specific organelles. Single-chain polymer nanoparticles (SCNPs) are a promising nanocarrier platform in biomedical applications due to their unique size range of 5-20 nm, modularity, and ease of functionalization. However, cytosolic delivery of SCNPs remains challenging. Here, we report the synthesis of active ester-functional SCNPs of approximately 10 nm via intramolecular thiol-Michael addition cross-linking and their functionalization with increasing amounts of tertiary amines 0 to 60 mol % to obtain SCNPs with increasing positive surface charges. No significant cytotoxicity was detected in bEND.3 cells for the SCNPs, except when SCNPs with high amounts of tertiary amines were incubated over prolonged periods of time at high concentrations. Cellular uptake of the SCNPs was analyzed, presenting different uptake behavior depending on the degree of functionalization. Confocal microscopy revealed successful cytosolic delivery of SCNPs with high degrees of functionalization (45%, 60%), while SCNPs with low amounts (0% to 30%) of tertiary amines showed high degrees of colocalization with lysosomes. This work presents a strategy to direct the intracellular location of SCNPs by controlled surface modification to improve intracellular targeting for biomedical applications

Pentafluorophenyl-based single-chain polymer nanoparticles as a versatile platform towards protein mimicry

Proteins are biopolymers folded into 3D-structures and are omnipresent in biological systems, where they fulfil a wide array of complex functions. Mimicking the exceptional characteristics of proteins with synthetic analogues may likewise give unprecedented control over a nanomaterial's pharmacokinetic behaviour, enabling controlled delivery of therapeutics or imaging agents. Recent advances in polymer science have enabled the formation of bio-inspired single-chain polymer nanoparticles (SCNPs), which are formed by intramolecular collapse of individual polymer chains, and display sizes ranging from 5-20 nm. Here, we describe the preparation of SCNPs containing activated ester moieties, facilitating SCNP functionalization without altering its backbone structure. Pentafluorophenyl-functional SCNPs were prepared through intramolecular thiol-Michael addition crosslinking of thiol-functional precursor copolymers. Post-formation functionalization of the resulting SCNPs through substitution of the activated pentafluorophenyl esters with a variety of amines resulted in a series of water-soluble SCNPs with fluorescent labels, 'click' functionality, amino acids and even peptides. This synthetic strategy offers a straightforward method towards SCNP modification and SCNP-protein hybrids, giving access to easily adjustable physicochemical properties and protein mimicry

Single-Chain Polymer Nanoparticles Targeting the Ookinete Stage of Malaria Parasites

Malaria is an infectious disease transmitted by mosquitos, whose control is hampered by drug resistance evolution in the causing agent, protist parasites of the genus Plasmodium, as well as by the resistance of the mosquito to insecticides. New approaches to fight this disease are, therefore, needed. Research into targeted drug delivery is expanding as this strategy increases treatment efficacies. Alternatively, targeting the parasite in humans, here we use single-chain polymer nanoparticles (SCNPs) to target the parasite at the ookinete stage, which is one of the stages in the mosquito. This nanocarrier system provides uniquely sized and monodispersed particles of 5-20 nm, via thiol-Michael addition. The conjugation of succinic anhydride to the SCNP surface provides negative surface charges that have been shown to increase the targeting ability of SCNPs to Plasmodium berghei ookinetes. The biodistribution of SCNPs in mosquitos was studied, showing the presence of SCNPs in mosquito midguts. The presented results demonstrate the potential of anionic SCNPs for the targeting of malaria parasites in mosquitos and may lead to progress in the fight against malaria