Surface Bioengineering of Diatom by Amine and Phosphate Groups for Efficient Drug Delivery

Abstract

The self-assembled existent biomaterials have been synthesized naturally with enormous three-dimensional structured porous with multifunctional properties (Sarikaya 1999). Diatoms are benthic photosynthetic brown algae, which is the most terrific living thing that can produce their exoskeleton with amorphous silica particles organically (Morse 1999; Sumper and Brunner 2006). Those outer shells arrayed with porous biosilica with distinctive 3D architecture, called frustules, with extremely organized pore structures, patterns of species and hierarchical arrangements with peculiar mechanical, molecular transport, ocular and bioluminescence properties (Parkinson and Gordon 1999; Lopez et al. 2005; Losic et al. 2009). Their biocompatibility and mechanical potency with humans and other species are highly prominent (Kröger and Poulsen 2008). The pores are displaying more dominancy on diatoms; hence the diatoms become smaller at each generation, even though the pore size remains same on diatom’s surface (Kröger and Poulsen 2008), so the identical pore size on diatom shell become a prospective biomaterial for the application of drug delivery. These features may well eradicate the low bioavailability of hydrophilic drugs and replace synthetic mesoporous silica materials as drug cargo loading (Lauritis 1968). Diatom frustules are available mainly as of two resources, including live diatom cultures with tiny amount of biomass and in the form of fossils diatomaceous earth (DE), in huge quantities. Owing to the silica chemistry of the diatom is having some limitations on those applications. Accordingly, to modify the biosilica material derived from diatoms, the significant efforts have recently been underwent technologically to convert it to be more suitable functional materials without disrupting the frustules morphologies and shapes. The conversion of biosilica into inorganic (MgO, TiO2, zeolites), semiconducting (Si–Ge), metal (Ag, Au) or organic (polyaniline) scaffolds has been demonstrated through several approaches including gas/solid displacement, chemical deposition, sol–gel synthesis and polymerization (Losic et al. 2007). The possible surface modification will generate new properties like localized surface plasmon (LSPR) and surface-enhanced Raman scattering (SERS) on diatom explored via simple mechanisms, which will have been generated from diatoms, functionalization with Au nanoparticles (Bao et al. 2009). The potency of drug cargo delivery from diatom biosilica through their nanoporous is proven by controlled drug releases. Diatom biosilica can also be modified with antibodies and enzymes (Gordon et al. 2009; Singh and Singh 2009; Downs Jr. et al. 2005). The impact of drug loading and release on surface functionalized diatom’s silica material, particularly investigating the properties of diatom surface and functionalization materials for both hydrophobic and hydrophilic drugs. The organosilanes and phosphonic acid such as 3-aminopropyltriethoxysilane [APTES] based self-assembled organic monolayers (SAM), N-(3-(trimethoxysilyl) propyl) ethylene diamine [AEAPTMS], 2-carboxyethyl-phosphonic acid [2-phos] were used for hydrophilic and 16-phosphono-hexadecanoic acid [16-phos] for hydrophobic drugs are used as chemical modifiers (Bariana et al. 2013a and Bariana et al. 2013b). Organosilanes APTES and AEAPTMS are amino functional groups containing amine modification agents and were mostly used for enhancing steady adsorption in numerous applications between organic compounds and silica substrates (Xu et al. 2003).