The important role of multidetector-AF4 in the study of gold nanoparticle bioconjugates life: synthesis, optimization, application in drug delivery

Gold nanoparticles (AuNPs) have emerged as a pivotal material in nanotechnology, thanks to their unique optical, electronic, and chemical properties. These properties make AuNPs highly desirable for a variety of applications, particularly in biosensing, where they serve as transducers, and in nano-pharmaceutics, where they function as drug carriers. However, despite their widespread use, the characterization, purification, and stability of AuNPs, particularly in their conjugated forms with biomolecules such as proteins, remain significant challenges. Conventional techniques often fall short in providing the necessary resolution and sensitivity, particularly when working under native conditions or in complex biological media. This research aims to address these gaps by leveraging advanced separation and detection techniques, specifically Asymmetrical Flow Field-Flow Fractionation (AF4) combined with multi-detection platforms, to develop robust methodologies for the comprehensive study of AuNPs and their bioconjugates. The research was structured around the application of AF4 and a suite of detection systems to address the challenges associated with AuNPs and their bioconjugates. AF4 is a sophisticated technique used for the separation and characterization of nanoparticles (NPs), polymers, and macromolecules. Unlike traditional chromatographic methods, AF4 does not rely on a stationary phase; instead, it uses a cross-flow field to separate particles based on their size and diffusion properties. This is particularly advantageous for the study of AuNPs and their conjugates, as it allows for the analysis of these species under native conditions, minimizing the risk of altering their structure or function. In this research, AF4 was employed to separate AuNPs with different surface coatings and to analyze their conjugation with BSA, a model protein commonly used in biosensing and pharmaceutical applications. These methodologies were applied across three distinct studies, each contributing to the overall understanding of AuNP behavior, conjugation efficiency, stability under various conditions, and their bioconjugates application prospects.