The Impact of Protein Corona in Nanoflare-based Biomolecular Detection and Quantification

Selective detection and precise quantification of biomolecules in intracellular settings play a pivotal role in the diagnostics and therapeutics of diseases, including various cancers and infectious epidemics. Because of this clinical relevance, nanoprobes with high sensitivity, wide tunability, and excellent biological stability have become of high demand. In particular, nanoflares based on gold nanoparticles have emerged as an attractive candidate for intracellular detection due to their efficient cellular uptake, enhanced binding affinity with complementary targets, and improved biological compatibility. However, nanoprobes, including these nanoflares, are known to be susceptible to the adsorption of proteins present in the biological environment, which leads to the formation of a so-called protein corona layer on their surface, leading to an altered targeting efficiency and cellular uptake. In this work, we leverage the nanoflares platform to demonstrate the effect of protein corona on biomolecular detection, quantification, as well as biological stability against enzymatic degradation. Nanoflares incubated in a biologically relevant concentration of serum albumin proteins (0.50 wt %) were shown to result in more than 20% signal reduction in target detection, with a decrease varying proportionally with the protein concentrations. In addition, similar signal reduction was observed for different serum proteins, and PEG backfilling was found to be ineffective in mitigating the negative impact induced by the corona formation. Furthermore, nuclease resistance in nanoflares was also severely compromised by the presence of the corona shell (∼2-fold increase in hydrolysis activity). This work demonstrates the consequences of an in situ formed protein corona layer on molecular detection/quantification and biological stability of nanoflares in the presence of nuclease enzymes, highlighting the importance of calibrating similar nanoprobes in proper biological media to improve the accuracy of molecular detection and quantification.