Nanoconjugates based on a novel organic-inorganic hybrid silsesquioxane and gold nanoparticles as hemocompatible nanomaterials for promising biosensing applications.

A new hybrid organic-inorganic silsesquioxane material, 3-n-propyl(2-amino-4-methyl)pyridium chloride (SiAMPyCl), was synthesized and successfully applied for the synthesis of stable nanoconjugates with gold nanoparticles (AuNPs-SiAMPy). SiAMPyCl was obtained through a simple sol-gel procedure by using chloropropyltrimetoxysilane and tetraethylorthosilicate as precursors and 2-amino-4-methylpyridine as the functionalizing agent. The resulting material was characterized by employing FTIR, XRD, and H-, C-, and Si-NMR spectroscopy. The synthesis of AuNPs-SiAMPy nanoconjugates was optimized through a 2 full factorial design. UV-VIS, FTIR, TEM, DLS, and ζ-potential measurements were used to characterize the nanoconjugates, which presented a spherical morphology with an average diameter of 5.8 nm. To investigate the existence of toxic effects of AuNPs-SiAMPy on blood cells, which is essential for their future biomedical applications, toxicity assays on human erythrocytes and leukocytes were performed. Interestingly, no cytotoxic effects were observed for both types of cells. The nanoconjugates were further applied in the construction of electrochemical immunosensing devices, aiming the detection of anti-Trypanosoma cruzi antibodies in serum as biomarkers of Chagas disease. The AuNPs-SiAMPy significantly enhanced the sensitivity of the biodevice, which was able to discriminate between anti-T. cruzi positive and negative serum samples. Thus, the AuNPs-SiAMPy-based biosensor showed great potential to be used as a new tool to perform fast and accurate diagnosis of Chagas disease. The promising findings described herein strongly confirm the remarkable potential of SiAMPyCl to obtain nanomaterials, which can present notable biomedical properties and applications.