In the last decade there has been profuse research efforts exploring the uses of iron oxide particles in nanomedicine. To a great extent, the efficiency of magnetic iron oxide nanoparticles for biomedical applications and the nanoparticles fate depend on how the nanoparticle surface interfaces with the proteins in a physiological environment. It is well reported how ungoverned protein corona can be detrimental for cellular uptake and targeting efficiency and how it can modify the nanoparticles biodistribution. Novel strategies are emerging to achieve enhanced and more reproducible performances of engineered nanoparticles with a custom-built protein corona. Here we report on a generalized protocol to preform a monolayer of human serum albumin (HSA) on superparamagnetic iron oxide nanoparticles (SPIONs) of different sizes. The resulting molecular structure is described by molecular dynamics simulations of the hybrid nanoconjugates. The number of proteins forming the corona and their disposition as a monolayer on the particle surface predicted by molecular simulations is in agreement with the results obtained from dynamic light scattering and electronic microscopy analysis. Moreover, by tryptophan fluorescence quenching, we determine a strong interaction between the SPIONs and the HSA endorsing the robustness of the proteinnanoparticles conjugates in this system. Besides, the effect of the HSA corona on the SPIONs efficiency as magnetic resonance imaging (MRI) contrast agents in water, human serum and in saline medium has been evaluated. The protein corona did not affect the efficiency of the SPIONs as T 2 contrast agents but reduce their efficiency as T 1. In addition, we observed a greater stability for HSA-SPIONs nanoconjugates in saline and in acid media preventing nanoparticle dissolution in extreme gastric conditions.

Red blood cell (RBC) hitchhiking has great potential in enhancing drug therapy, by improving targeting and reducing rapid clearance of nanoparticles (NPs). However, to improve the potential for clinical translation of RBC hitchhiking, a more thorough understanding of the RBC-NP interface is needed. Here, we evaluate the effects of NP surface parameters on the success and biocompatibility of NP adsorption to extracted RBCs from various species. Major differences in RBC characteristics between rabbit, mouse and human were proven to significantly impact NP adsorption outcomes. Additionally, the effects of NP design parameters, including NP hydrophobicity, zeta potential, surfactant concentration and drug encapsulation, on RBC hitchhiking are investigated. Our studies demonstrate the importance of electrostatic interactions in balancing NP adsorption success and biocompatibility. We further investigated the effect of varying the anti-coagulant used for blood storage. The results presented here offer new insights into the parameters that impact NP adsorption on RBCs that will assist researchers in experimental design choices for using RBC hitchhiking as drug delivery strategy.

To date, surface plasmon resonance (SPR) biosensors have been exploited in numerous different contexts while continuously pushing boundaries in terms of improved sensitivity, specificity, portability and reusability. The latter has attracted attention as a viable alternative to disposable biosensors, also offering prospects for rapid screening of biomolecules or biomolecular interactions. In this context here, we developed an approach to successfully regenerate a fiber-optic (FO)-SPR surface when utilizing cobalt (II)-nitrilotriacetic acid (NTA) surface chemistry. To achieve this, we tested multiple regeneration conditions that can disrupt the NTA chelate on a surface fully saturated with His6-tagged antibody fragments (scFv-33H1F7) over ten regeneration cycles. The best surface regeneration was obtained when combining 100 mM EDTA, 500 mM imidazole and 0.5% SDS at pH 8.0 for 1 min with shaking at 150 rpm followed by washing with 0.5 M NaOH for 3 min. The true versatility of the established approach was proven by regenerating the NTA surface for ten cycles with three other model system bioreceptors, different in their size and structure: His6-tagged SARS-CoV-2 spike fragment (receptor binding domain, RBD), a red fluorescent protein (RFP) and protein origami carrying 4 RFPs (Tet12SN-RRRR). Enabling the removal of His6-tagged bioreceptors from NTA surfaces in a fast and cost-effective manner can have broad applications, spanning from the development of biosensors and various biopharmaceutical analyses to the synthesis of novel biomaterials.