lysozyme molecule on the Ag surface [8–10]. These articles report the orientation of the aromatic amino acid side-chains located on the surface of the metal electrodes. The role of an α -helical component of the lysozyme molecule for binding on the metal surface has been shown [8, 9] and a recent study has reported the conformational changes in lysozyme molecule with temperature, while adsorbed on a gold nano-patterned SERS substrate [17]. Thus previous studies indicate the possible regions of interaction of the lysozyme molecule while interacting on the surface of metal colloids. It is necessary to probe the specific region of binding of the protein molecule to the Ag colloidal surface to permit an understanding of which regions of the protein would be free to interact with ligands and/or drugs. For example, the antimicrobial macromolecule formed by a lysozyme-polyphenol complex can be used as a carrier for phenolic antioxidants. Epigallocatechin gallate (EGCG) [18] and Triclosan [19] molecules are known to form complexes with lysozyme via Trp-62 and Trp-63 residues. The knowledge of the specific binding site in Ag-lysozyme complex can provide guidelines to develop nanoparticle tagged lysozyme molecule for drug delivery. It may be noted that the lysozyme is a potential carrier molecule as a renal-selective drug carrier for delivery of the angiotensin-converting enzyme (ACE) inhibitor captopril [20]. Synthesis route for preparing stabilized particles: Ag nanoparticles have been syn- thesized by chemical routes, using sodium borohydride (NaBH 4 ) as reducing agents. Silver nitrate (AgNO 3 ), sodium borohydride (NaBH 4 ) of analytical reagent grade (SRL, India), were used to prepare the Ag sol. A colloidal silver solution was prepared in deionized wa- ter following the method described by Creighton et al. [21]. Essentially, in this chemical route, AgNO 3 is reduced by an excess amount of NaBH 4 . 2.2 × 10 − 3 M AgNO 3 was added dropwise to 1 mM NaBH 4 at 4 ◦ C. Stirring for 20 minutes was necessary to stabilize the colloidal solution. Later, it was left at room temperature for approximately 1 hour. The excess NaBH 4 evaporated and the remaining solution became transparent yellow in color. Colloids generated by above method were stable over a considerable period of time (4-6 weeks). However, all our reported results are either with freshly prepared Ag sol or aged only for a day. Chicken egg-white lysozyme was obtained from Sigma-Aldrich. In solution, depending on II. MATERIALS AND METHODS 3