Many biomolecules, mainly proteins, adsorb onto polymer particles to form a dynamic protein corona in biological environments. The protein corona can significantly influence particle-cell interactions, including internalization and pathway activation. In this work, we demonstrate the differential roles of a given protein corona formed in cell culture media in particle uptake by monocytes and macrophages. By exposing disulfide-stabilized poly(methacrylic acid) nanoporous polymer particles (PMASH NPPs) to complete cell growth media containing 10% fetal bovine serum, a protein corona, with the most abundant component being bovine serum albumin, was characterized. Upon adsorption onto the PMASH NPPs, native bovine serum albumin (BSA) was found to undergo conformational changes. The denatured BSA led to a significant decrease in internalization efficiency in human monocytic cells, THP-1, compared with the bare particles, due to reduced cell membrane adhesion. In contrast, the unfolded BSA on the NPPs triggered class A scavenger receptor-mediated phagocytosis in differentiated macrophage-like cells (dTHP-1) without a significant impact on the overall internalization efficiency. Taken together, this work demonstrates the disparate effects of a given protein corona on particle-cell interactions, highlighting the correlation between protein corona conformation in situ and relevant biological characteristics for biological functionalities.

Understanding the interactions between drug carriers and cells is of importance to enhance the delivery of therapeutics. The release of therapeutics into different intracellular environments, such as the lysosomes or the cell cytoplasm, will impact their pharmacological activity. Herein, we investigate the intracellular fate of layer-by-layer (LbL)-assembled, submicrometer-sized polymer hydrogel capsules in a human colon cancer derived cell line, LIM1899. The cellular uptake of the disulfide-stabilized poly(methacrylic acid) (PMA(SH)) capsules by colon cancer cells is a time-dependent process. Confocal laser scanning microscopy and transmission electron microscopy reveal that the internalized capsules are deformed in membrane-enclosed compartments, which further mature to late endosomes or lysosomes. We further demonstrate the utility of these redox-responsive PMA(SH) capsules for the delivery of doxorubicin (DOX) to colon cancer cells. The DOX-loaded PMA(SH) capsules demonstrate a 5000-fold enhanced cytotoxicity in cell viability studies compared to free DOX.

Targeted delivery of drugs to specific cells allows a high therapeutic dose to be delivered to the target site with minimal harmful side effects. Combining targeting molecules with nanoengineered drug carriers, such as polymer capsules, micelles and polymersomes, has significant potential to improve the therapeutic delivery and index of a range of drugs. We present a general approach for functionalization of low-fouling, nanoengineered polymer capsules with antibodies using click chemistry. We demonstrate that antibody (Ab)-functionalized capsules specifically bind to colorectal cancer cells even when the target cells constitute less than 0.1% of the total cell population. This precise targeting offers promise for drug delivery applications.