Heparin Assisted Photochemical Synthesis of Gold Nanoparticles and Their Performance as SERS Substrates

Abstract

Reactive and pharmaceutical-grade heparins were used as biologically compatible reducing and stabilizing agents to photochemically synthesize colloidal gold nanoparticles. Aggregates and anisotropic shapes were obtained photochemically under UV black-light lamp irradiation (λ = 366 nm). Heparin-functionalized gold nanoparticles were characterized by Scanning Electron Microscopy and UV-Vis spectroscopy. The negatively charged colloids were used for the Surface Enhanced Raman Spectroscopy (SERS) analysis of differently charged analytes (dyes). Measurements of pH were taken to inspect how the acidity of the medium affects the colloid-analyte interaction. SERS spectra were taken by mixing the dyes and the colloidal solutions without further functionalization or addition of any aggregating agent.

Newly designed silver coated-magnetic, monodisperse polymeric microbeads as SERS substrate for low-level detection of amoxicillin

“…5. As seen here, the intensities of the peaks at 1391, 1436, and 1623 cm À1 with their band assignments CeH in-plane ring deformation, CeN asymmetric stretching, CeC ring stretching, respectively were correlated with the MB concentration [37]. The most apparent change was observed for the peak at 1623 cm À1 .…”

Calligraphed Selective Plasmonic Arrays on Paper Platforms for Complementary Dual Optical “ON/OFF Switch” Sensing

“…Similar results were obtained in the case of the anionic RB capture by the positively charged CTAB layer that covers both AuBPs and AuNRs calligraphed on paper. Figure 3 c,g—red spectra prove that the anionic molecules were selectively detected by both positively charged CTAB-coated nanostructures, SERS spectrum possessing the characteristic bands at 610 cm −1 (C–C–C ring in-plane vibration), 750 cm −1 (C–Cl stretching), 1337 cm −1 (C–C stretching in ring), 1490 cm −1 (C=C asymmetric stretching in ring), 1547 cm −1 (C–C stretching in ring), 1612 cm −1 (C=C symmetric stretching in ring) [ 16 , 37 ] as predicted in Table 1 . As reference, the corresponding Raman spectra were collected on the calligraphed free RB molecules (10 −2 M concentration) onto the bare Whatman paper ( Figure S7 —brown spectrum).…”

Antifungal and Cytotoxic Evaluation of Photochemically Synthesized Heparin-Coated Gold and Silver Nanoparticles

“…The method used for the synthesis of the nanoparticles was reported by us before [26], with modifications such as the use of fungicidal lamps of 254 nm wavelength as the irradiation source and magnetic stirring of the aqueous solutions during the procedure.…”

“…On the other hand, there are studies which report that heparin does not own such antimicrobial potential [ 19 ]. Because of its polyanionic nature arising from carboxylate groups and O - and N -sulfates [ 20 , 21 ], it is a highly reactive molecule and it has been used in metal nanoparticle synthesis as a capping and reducing agent in wet chemistry approaches [ 22 , 23 , 24 , 25 ] and in a photochemical method developed previously by our group [ 26 ]. In general, the photochemical method for nanoparticle synthesis has advantages, since it is a clean process with high spatial resolution and versatility (it can be used with a wide variety of materials, e.g., emulsions, surfactants, polymer films, polymers, glasses, and cells) [ 27 ].…”