Quartz Crystal Microbalance Method to Measure Nanoparticle-Receptor Interactions and Evaluate Nanoparticle Design Efficiency

Ultrathin Flexible Silica Nanosheets with Surface Chemistry-Modulated Affinity to Mammalian Cells

Flexibility of nanomaterials is challenging but worthy to tune for biomedical applications. Biocompatible silica nanomaterials are under extensive exploration but are rarely observed to exhibit flexibility despite the polymeric nature. Herein, a facile one-step route is reported to ultrathin flexible silica nanosheets (NSs), whose low thickness and high diameter-to-thickness ratio enables folding. Thickness and diameter can be readily tuned to enable controlled flexibility. Mechanism study reveals that beyond the commonly used surfactant, the "uncommon" one bearing two hydrophobic tails play a guiding role in producing sheeted/layered/shelled structures, while addition of ethanol appropriately relieved the strong interfacial tension of the assembled surfactants, which will otherwise produce large curled sheeted structures. With these ultrathin NSs, it is further shown that the cellular preference for particle shape and rigidity is highly dependent on surface chemistry of nanoparticles: under high particle-cell affinity, NSs, and especially the flexible ones will be preferred by mammalian cells for internalization or attachment, while this preference is basically invalid when the affinity is low. Therefore, properties of the ultrathin silica NSs can be effectively expanded and empowered by surface chemistry to realize improved bio-sensing or drug delivery.

Artificial protein coronas: directing nanoparticles to targets

The protein corona surrounding nanoparticles (NPs) offers exciting possibilities for targeted drug delivery. However, realizing this potential requires direct evidence of corona-receptor interactions in vivo; a challenge hampered by the limitations of in vitro settings. This opinion proposes that utilizing engineered protein coronas can address this challenge. Artificial coronas made of selected plasma proteins retain their properties in vivo, enabling manipulation for specific receptor targeting. To directly assess corona-receptor interactions mimicking in vivo complexity, we propose testing artificial coronas with recently adapted quartz crystal microbalance (QCM) setups whose current limitations and potential advancements are critically discussed. Finally, the opinion proposes future experiments to decipher corona-receptor interactions and unlock the full potential of the protein corona for NP-based drug delivery.

A generic approach based on long-lifetime fluorophores for the assessment of protein binding to polymer nanoparticles by fluorescence anisotropy

Quantitation of protein-nanoparticle interactions is essential for the investigation of the protein corona around NPs in vivo and when using synthetic polymer nanoparticles as affinity reagents for selective protein recognition in vitro. Here, a method based on steady-state fluorescence anisotropy measurement is presented as a novel, separation-free tool for the assessment of protein-nanoparticle interactions. For this purpose, a long-lifetime luminescent Ru-complex is used for protein labelling, which exhibits low anisotropy when conjugated to the protein but displays high anisotropy when the proteins are bound to the much larger polymer nanoparticles. As a proof of concept, the interaction of lysozyme with poly(N-isopropylacrylamide-co-N-tert-butylacrylamide-co-acrylic acid) nanoparticles is studied, and fluorescence anisotropy measurements are used to establish the binding kinetics, binding isotherm and a competitive binding assay.

The Transformative Potential of Lipid Nanoparticle-Protein Corona for Next-Generation Vaccines and Therapeutics

The integration of the lipid nanoparticle (LNP)-protein corona as a pioneering approach for the development of vaccines against the present and future SARS-CoV-2 variants of concern marks a significant shift in the field. This concept holds great promise, offering a universal platform that can be adaptable to combat future pandemics caused by unknown viruses. Understanding the complex interactions among the protein corona, LNPs, and receptors is crucial for harnessing its potential. This knowledge will allow optimal vaccine formulations and improve their effectiveness. Safety assessments are essential to ensure suitability for human use, compliance with regulatory standards, and rigorous quality control in manufacturing. This transformative workflow requires collaborative efforts, expanding our foundational knowledge and translating advancements from the laboratory to clinical reality. The LNP-protein corona approach represents a paradigmatic shift with far-reaching implications. Its principles and insights can be leveraged beyond specific applications against SARS-CoV-2, enabling a universal platform for addressing viral threats, cancer, and genetic diseases.