Chemical modification of Nitzschia panduriformis's frustules for protein and viral nanoparticle adsorption

Abstract

The frustule of diatoms, through appropriate chemical modification, can be developed for a high adsorption level of recombinant proteins and viral nanoparticles. Field emission scanning electron microscopy (FE-SEM) analysis of clean frustules revealed a 3D loculate areolae structure (valvar phase porous pattern of the siliceous cell wall). Isocyanatopropyl triethoxysilane (IPS) and iminodiacetic acid (IDA) were used to immobilize Cu2+ ions (an average Cu2+ adsorption capacity about 190μmol of Cu2+/ml of the Cu2+-coupled biosilica reached). FE-SEM, energy dispersion X-ray spectroscopy (EDS) and Fourier transform infrared (FT-IR) were used to confirm the chemical modification of the Cu2+-coupled biosilica. Protein adsorption was confirmed with the detection of a recombinant (His)6-tagged green fluorescent protein binding using fluorescent microscopy. Infectious bursal disease virus VP2-441 subviral particles (SVPs) were found to bind to the Cu2+-coupled biosilica (approximately 3×10−9mol of VP2-441 SVPs/ml of modified frustules), a level higher than the previously obtained 9×10−10mol/ml for SVP binding using a commercial Ni–NTA resin. These give diatom frustules the potential to be developed into a material useful in viral nanoparticle purification systems or as a biosensor for the detection of viruses.