RICARDO FRANCO, UCIBIO - FCT NOVA

Immunodetection based in gold nanoparticles: beyond lateral flow assays

Chair: Pedro Viana Baptista, UCIBIO - FCT NOVA

Abstract - Immunodetection based in gold nanoparticles: beyond lateral flow assays

Below is the scientific abstract for the work I will present. I will give you a collaborator-based view of my work in which Science is made by People and for the People.

Nanoimmunoassays based on gold nanoparticles (AuNPs) associate high sensitivity imparted by nanoscale properties with the well-known specificity associated with antibody detection. For the construction of AuNP-antibody or AuNP-antigen conjugates we synthesize AuNPs and further functionalize them with an alkanethiol bifunctional linker that provides a bio-friendly and uniform negatively charged surface at physiological pH, that we have been using successfully for protein conjugation, either covalently or by physisorption. Both approaches were used for the conjugation with monoclonal antibodies against malaria antigens in a competitive and fluorescence-based assay. The type of conjugation of the antibody to the AuNPs determines the activity of the antibody, with conjugates formed by physisorption being more active. Further studies of these conjugates by Agarose Gel Electrophoresis (AGE) and Differential Centrifugal Sedimentation (DCS) revealed two different models for antigen binding to AuNP-antibody conjugates. Furthermore, DCS was used to show inhibition of antigen binding in the presence of human plasma, a realistic testing condition, of high relevance to the implementation of immunoassays at the clinical level. Recent characterization data will be presented for star-shaped AuNP-antibody conjugates, further functionalized with a Raman probe, with intended utilization in a SERS (Surface-Enhanced Raman Spectroscopy)-based microfluidics platform for food toxin antigen detection. Taking an innovative approach to immunoassays, we are using AuNP-synthetic antigen conjugates to detect circulating antibodies against pneumocystis. The proof-of-concept for this serological assay was established by AGE using sera from infected mice. Studies in human plasma indicate successful application of this detection scheme in a lateral flow immunoassay format, as a non-invasive strategy for detection of pneumocystis in clinical samples.  

Short Bio

I have finished my Licenciatura in Química Aplicada (Biotechnology branch) in 1989 here in FCT/NOVA, and have been working here as Monitor, Assistente, Professor, ever since. I finished my PhD in 1995, in the area of Bioinorganic Chemistry under the joint supervision of José Moura here in FCT/NOVA and Gloria Ferreira in the University of South Florida (USA), and have made several post-doctoral stays in the US (University of South Florida College of Medicine in Tampa, Florida and Sandia National Laboratories in Albuquerque, New Mexico)  and in Germany (Tierärztliche Hochschule Hannover), the latter with an Alexander von Humboldt Foundation Grant. In 2001 I changed my area of research from Bioinorganic Chemistry to Bionanotechnology, Raman spectroscopy (and SERS) being the bridge between these apparently so different areas. In 2016 I did my Agregação in Physical Biochemistry.

Publication info: 76 publications; 2098 citations; H-index=26
Web of Science Researcher ID: C-5247-2008
ORCID: 0000-0002-5139-2871