A novel type of cellular-uptake-shielding multifunctional envelope-type mesoporous silica nanoparticle (MEMSN) was designed for tumor-triggered targeting drug delivery to cancerous cells. β-Cyclodextrin (β-CD) was anchored on the surface of mesoporous silica nanoparticles via disulfide linking for glutathione-induced intracellular drug release. Then a peptide sequence containing Arg-Gly-Asp (RGD) motif and matrix metalloproteinase (MMP) substrate peptide Pro-Leu-Gly-Val-Arg (PLGVR) was introduced onto the surface of the nanoparticles via host-guest interaction. To protect the targeting ligand and prevent the nanoparticles from being uptaken by normal cells, the nanoparticles were further decorated with poly(aspartic acid) (PASP) to obtain MEMSN. In vitro study demonstrated that MEMSN was shielded against normal cells. After reaching the tumor cells, the targeting property could be switched on by removing the PASP protection layer via hydrolyzation of PLGVR at the MMP-rich tumor cells, which enabled the easy uptake of drug-loaded nanoparticles by tumor cells and subsequent glutathione-induced drug release intracellularly.

Materials that resist nonspecific protein adsorption are needed for many applications. However, few are able to achieve ultralow fouling in complex biological milieu. Zwitterionic polymers emerge as a class of highly effective ultralow fouling materials due to their superhydrophilicity, outperforming other hydrophilic materials such as poly(ethylene glycol). Unfortunately, there are only three major classes of zwitterionic materials based on poly(phosphorylcholine), poly(sulfobetaine), and poly(carboxybetaine) currently available. Inspired by trimethylamine N-oxide (TMAO), a zwitterionic osmolyte and the most effective protein stabilizer, we here report TMAO-derived zwitterionic polymers (PTMAO) as a new class of ultralow fouling biomaterials. The nonfouling properties of PTMAO were demonstrated under highly challenging conditions. The mechanism accounting for the extraordinary hydration of PTMAO was elucidated by molecular dynamics simulations. The discovery of PTMAO polymers demonstrates the power of molecular understanding in the design of new biomimetic materials and provides the biomaterials community with another class of nonfouling zwitterionic materials.

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Enhancement of the light emission of ZnO films was observed by coupling through localized surface plasmons. By sputtering Ag islands onto ZnO films, their band gap emission coming through the Ag island films was enhanced by threefolds, while the defect emission was quenched. The enhancement was found to be mainly dependent on the sputtering time of the Ag islands, which is related to the island size. Furthermore, the relative spectral position between the ZnO emission band and the localized surface plasmon resonance bands of Ag islands was found to be decisive for the enhancement or quenching of photoluminescence, indicating that the emission intensity of ZnO films can be controlled by the Ag island size and the localized surface plasmon resonance band position.

Poly(ethylene glycol) (PEG) conjugation has been the gold standard to ameliorate the pharmacokinetic (PK) and immunological profiles of proteins. PEG polymer does become immunogenic once attached to proteins, evoking PEG-specific antibody (Ab) responses. The anti-PEG Abs could cause PEGylated biologic treatments to fail and even result in lethal adverse reactions. Thus the zwitterionic poly(carboxybetaine) (PCB) has been introduced as a PEG substitute for protein modification. Addressed herein is anti-polymer Ab induction by conjugating PEG and PCB polymers to a series of carrier proteins with escalating immunogenicity. Results indicate that titers of PEG-specific Abs were quantitatively correlated to the immunogenicity of carrier proteins, whereas the generation of PCB-specific Abs was minimal and insensitive to increased protein immunogenicity. This work provides insight into the immunological properties of PEG and PCB and has far-reaching implications for the development of polymer-protein conjugates.