ABSTRACT
Recent research developments in the area of nanoscience and nanotechnology have led to tremendous applications in the area of biomedicines such as drug/gene carriers, cell marking and tracking agents, hyperthermia treatments, and contrast enhancers in cell/tissue imaging modalities. The shape- and size-dependent unique physicochemical properties of NPs are fundamental to these applications. The success of medical treatment depends on the control on the delivery of drugs to a specific target organ. Additionally, to understand the efficacy of treatment of complex diseases, one needs to understand the complex spatiotemporal interplay of biomolecules in various cellular processes and signaling pathways. Key to successful implementation of nanoparticles in biomedicines is precise control over the synthesis and surface modification of the particles. In myriad reports from nanomaterial safety assessment, it is recommended that NPs possess certain specific criteria for their use in biomedicine, which are: (i) possess minimum toxicity, (ii) prevent nonspecific interactions, (iii) be stable in different physiological conditions, and (iv) avoid premature release of drug and nucleotides (in gene therapy). Keeping the above parameters in mind, modification of NP surfaces becomes a vital parameter for their interaction with specific cell surface targets. In this chapter, we will highlight the methods commonly being used for nanoparticle surface modification intended for biological applications. The common methods used to achieve controlled nanoparticle surface modification are ligand exchange, surface silanization, coating with polymers, and functionalization through different biomolecules. Specific arrangements of atoms at the surface of nanoparticles and their interplay with incoming ligands are essential criteria to ensure surface modification of nanoparticles. It is well documented that nanoparticles can be synthesized in both aqueous and organic media with the same ease using suitable capping molecules.
