Synthesis of Cellulose Nanofibril Bound Silver Nanoprism for Surface Enhanced Raman Scattering

Abstract

Silver nanoprisms (AgNPs) were robustly synthesized using TEMPO-oxidized cellulose nanofibrils (CNFs) as a dual capping and shape-regulating agent for the first time. Reducing AgNO 3 with NaBH 4 in CNF suspensions produced smaller but more uniform Ag nanospheres (AgNSs) with increasing Ag + /CNF ratios. CNF bound AgNSs were facilely transformed to AgNPs by etching with H 2 O 2 , supporting the capping and shape-regulating capability of CNFs. AgNPs could also be synthesized directly in a one-shot reduction reaction with NaBH 4 in the presence of both CNFs and H 2 O 2 . The AgNPs transformed from CNF bound AgNSs are similar to those synthesized directly, but more stable against H 2 O 2 . Successful synthesis of AgNPs with 80−320 nm truncated edges was confirmed by light blue solution color, sharp out-of-plane quadruple resonance peak at 334 nm and prominent in-plane dipole resonance peaks at 762−900 nm. The [111] lattice plane of AgNP was clearly evident by its predominant XRD peak at 38°, confirming the unique shape-regulating ability of the nearly fully surface carboxylated CNFs. The CNF surface bound AgNPs were easily fabricated into freestanding CNF/AgNPs films that showed excellent surface enhanced Raman scattering of Rhodamine 6G with analytical enhancement factor of 5 × 10 3 in contrast to none from the CNF/AgNSs film.

Protein-aided formation of triangular silver nanoprisms with enhanced SERS performance

“…Only a few attempts have been made on the bioassisted seeded growth of shape-selective noble NPs with improved morphological yield. 46,47 Previously, our group has demonstrated that the morphology and optical properties of noble metal NPs could be modulated by the concentration and the structure of the CTPR proteins. 48 CTPR is a de novo protein sequence based on the tertratricopeptide repeat family.…”

Comparison of Triangular Silver Nanoprisms with Different Capping Agents and Structural Size for H2O2 Etching-Based Biosensors

“…18 Serving as a¯rst reported stabilizer, citrate has been widely used because its three-fold symmetry can preferentially match Ag (111) facets, blocking the growth along the vertical axis and allowing extensive growth along the lateral direction. [19][20][21] Except for citrate capping, hydroxyl group-containing molecules, such as ethanol and glycerol, have also been reported as secondary ligands to improve the size distribution of nanoprisms even though they are not essential to the formation of silver nanoprisms. Therefore, in this study, we synthesized TSNPRs according to the direct chemical reaction approach reported by Yin et al in which TSNPRs were stabilized by citrate in the absence or presence of secondary capping agents with carboxyl groups, such as ethanol and glycerol.…”

Tuning of Ag Nanoparticle Properties in Cellulose Nanocrystals/Ag Nanoparticle Hybrid Suspensions by H2O2 Redox Post-Treatment: The Role of the H2O2/AgNP Ratio

“…Finally, biopolymeric templates such as cellulose nanocrystals (CNCs) and nanofibers (CNFs) can also be used as stabilizers in the synthesis of AgNPs and AgNPrisms, allowing the production of new hybrid nanomaterials. These studies [33][34][35][36] used modified CNC and CNF surface chemistry. In this context, 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-oxidized CNFs appear to be an excellent substrate for the stabilization of AgNPs synthesized by NaBH 4 reduction since most of the surface primary C6 hydroxyls can be converted to carboxylates by TEMPO oxidation [37].…”