Site-specific conjugation of an antibody on a gold nanoparticle surface for one-step diagnosis of prostate specific antigen with dynamic light scattering

Abstract

Small dimensions of gold nanoparticles (AuNPs) necessitate antibodies to be immobilized in an oriented fashion in order to conserve their antigen binding activity for proper function. In this study, we used the previously described UV-NBS method to site-specifically incorporate thioctic acid (TA) functionality into antibodies at the conserved nucleotide-binding site (NBS). Modified antibodies were immobilized on AuNP surface in an oriented manner utilizing the newly incorporated TA functionality while maintaining antibody structure and activity. The resulting antibody functionalized AuNPs via the UV-NBS method demonstrated significantly enhanced antigen detection capabilities and improved antigen detection sensitivity with high level of selectivity when compared to other commonly used AuNP functionalization methods. Our results demonstrate that the limit of detection (LOD) for AuNPs functionalized via the UV-NBS method was 55 pM PSA, which is 40, 851, and 5873-fold improved over the other immobilization methods: EDC-NHS, thiol reduction, and ionic interaction, respectively. Consequently, the UV-NBS method provides a universal, site-specific functionalization method that generates highly sensitive and more stable antibody functionalized AuNPs that is amenable to any available detection and treatment assay with potential significant implications.

Gold Nanoparticles in Conjunction with Nucleic Acids as a Modern Molecular System for Cellular Delivery

“…AuNPs are therefore good candidates for in vivo imaging and studies compared to other materials like organic dyes or quantum dots. Taken together, due to the negligible toxicity of gold, and the simplicity of the controlled synthesis of AuNPs and functionalization, it became of interest to utilize AuNPs in conjunction with biomolecules such as nucleic acids [19][20][21], peptides [22], proteins [23,24], antibodies [25,26], and chemotherapeutic agents [27]. An advantage of conjugated AuNPs is improved effectiveness of the active ligands bound to the nanoparticle.…”

“…For example, owing to their optical properties, AuNPs may be introduced into photothermal therapy [31,32], which may further be developed by coating AuNPs with selective moieties targeting a specific cancerous cell [33,34]. Mentioned above optical properties became of interest in the field of bioimaging, where AuNPs serve as probes to visualize cellular compartments and allow to follow nanoparticles' cellular uptake, specificity and locations, which might be used for the targeted therapies [26,35,36]. In the greater scale, AuNPs were shown to aid mapping of lymph nodes [37], or vascular blood flow [38].…”

Designer covalent heterobivalent inhibitors prevent IgE-dependent responses to peanut allergen

“…1B) (23,24). We identified a molecule, indole-3 butyric acid (IBA) that specifically binds to NBS with moderate affinity (K d = 2-10 μM) (23,25,26). Targeting two independent sites on sIgEs simultaneously, ABS (with a peptide epitope) and NBS (with IBA), enables cHBIs to have both increased avidity and selectivity for target sIgEs.…”

Using gold nanoparticles in diagnosis and treatment of melanoma cancer

“…For instance, an interesting subject that has recently attracted the attention of scientists is the ability of AuNP-antibody conjugation for penetration into living cells such as cancer cells, leading the comprehensive evaluation of cancer cells regarding biological behaviours, metastatic tendency and curative susceptibility [42]. And also AuNPs are used as intracellular probes for cellular compartments such as mitochondria, endosomes and the cell nucleus by targeting them as well as to monitor intracellular drug release [43].…”