Inkjet printed patterns of polyamidoamine dendrimer functionalized magnetic nanostructures for future biosensing device application

Inkjet printing technology holds a great potential for fabrication of biosensor device. An optimized programmed printing makes the processing steps easier on a variety of substrates at low cost. The drop-on-demand piezoelectric mode of printing can construct a design pattern with low volume of material at specified position onto a suitable substrate. But to achieve this successfully, a formation of stable ink suspension remains the most challenging task. In recent times, nanoparticles are considered to pave a way for miniaturization of biosensing devices. Thus, we synthesized, characterized and investigated the stability of magnetic Fe3O4 nanoparticles stabilized by the polyamidoamine (PAMAM = N(CH2CH2C(O)NHCH2CH2NH2)(CH2CH2N(CH2CH2C(O)NHCH2CH2NH2)2)2) dendrimer (PAMAM@Fe3O4). A best stable ink dispersion of PAMAM@Fe3O4 nanoparticles was obtained in a solvent mixture of 70% ethylene glycol and 30% distilled water. The nanoparticle ink with surface tension of 57.47 mN/m and viscosity of 5.45 mPa/s formed a narrow and uniform printed pattern onto graphene paper. Further, as a model protein for future biosensing application, antibody against alpha-fetoprotein was conjugated onto the dendritic surface and printed onto graphene paper. The characterization of the printed pattern by TEM revealed spherical morphology, whereas SEM provided evidence of difference in printed line width and spacing of nanoparticles and antibody conjugated nanoparticles. As a proof-of-concept, the study demonstrated a printable ink dispersion based on PAMAM@Fe3O4 nanoparticles for future miniaturization of biosensing steps on a chip-based platform.