Gold nanoparticles functionalized with antibodies: a colorimetric analysis for implementation in PoC devices

The growing interest in the fast and easy identification of many biomarkers for several diseases, supporting a future precision medicine, results in the development of miniaturized, user-friendly, automated, and portable sensing systems able to provide a real-time and reliable response. Herein we evaluate the sensing capability of gold nanoflowers (AuNFs) for their integration in the setup of the Color Picker System, a Point-of-Care (PoC) sensing device developed by our group for a user-friendly colorimetric detection of molecules. A simulation study measures the color changes arising from the variations in the dielectric environment around the AuNFs surface. The process starts with the synthesis of AuNFs and their functionalization with 3-Mercaptopropionic acid. The measured transmittance spectra of the AuNFs before and after the functionalization, have been combined with the spectra of two different light sources to simulate the spectral response of the light transmitted through the colloidal dispersion. The calculated spectra have been converted into vectors in different color spaces producing the color chart. The sensitivity of the AuNFs has been evaluated as Euclidian distance between two consecutive points in the color chart, but also as differences in the RGB channels, that are the one returned from the Color Picker System. The AuNFs showed the greatest distances in the color chart and the greatest differences in the RGB when using the Cold LED as light source. The chromatic changes arising from their use make the AuNFs a potential sensing platform to be inserted into the Color Picker System for antibodies sensing.