Synthesis of Stable Citrate-Capped Silver Nanoprisms

Abstract

Citrate-stabilized silver nanoprisms (AgNPrs) can be easily functionalized using well-developed thiol based surface chemistry that is an important requirement for biosensor applications utilizing localized surface plasmon resonance (LSPR) and surface-enhanced Raman Scattering (SERS). Unfortunately, currently available protocols for synthesis of citrate-coated AgNPrs do not produce stable nanoparticles thus limiting their usefulness in biosensing applications. Here we address this problem by carrying out a systematic study of citrate-stabilized, peroxide-based synthesis of AgNPrs to optimize reaction conditions for production of stable and reproducible nanoprisms. Our analysis showed that concentration of secondary reducing agent, l-ascorbic acid, is critical to AgNPr stability. Furthermore, we demonstrated that optimization of other synthesis conditions such as stabilizer concentration, rate of silver nitrate addition, and seed dilution result in highly stable nanoprisms with narrow absorbance peaks ranging from 450 nm into near-IR. In addition, the optimized reaction conditions can be used to produce AgNPrs in a one-pot synthesis instead of a previously described two-step reaction. The resulting nanoprisms can readily interact with thiols for easy surface functionalization. These studies provide an optimized set of parameters for precise control of citrate stabilized AgNPr synthesis for biomedical applications.

Robust Synthesis of Size-Dispersal Triangular Silver Nanoprisms via Chemical Reduction Route and Their Cytotoxicity

“…These distinctive colors of silver nanostructure are because of a unique phenomenon well-known as plasmon absorbance, where incident light generates fluctuations in conveyance electrons on the surface of the nanoparticles and electromagnetic radiation is captivated. This clarifies the robust synthesis of Ag-NPrs in relevant time in comparison with other synthetic approaches that may take over a day or so, and overcomes the aggregation and redshift defects [23,40,41,42].…”

Photochemical Formation of Tunable Gold Nanostructures Using Versatile Water‐Soluble Thiolate Au(I) Precursor

“…Citrate is well known to serve as a multifunctional reagent in photochemical and thermal synthesis of MNPs . In addition, to being a reducing agent, citrate has a crucial role as a charge stabilizing agent for AgNPs, as well as complexing agent for silver ions during nucleation and growth stages . Figure b shows UV–vis spectra and representative EM images of AuNSs prepared using different citrate/Au ratios.…”

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

“…Callegari et al [22] indicate that irradiance conditions can transform AgNPs in suspension into larger NPs with different shapes, demonstrating that the photochemical growth of metallic NPs can be controlled by selecting the light color. Other methods to synthesize AgNPs and AgNPrisms are based on the chemical reduction of silver ions [23][24][25]. Several studies [10,23,[25][26][27] propose the use of a reducing agent to produce the Ag seeds (e.g., sodium borohydride, NaBH 4 ) and the addition of a capping agent to promote AgNP stabilization (e.g., trisodium citrate (TSC); polyvinylpirrolidine (PVP); and dextran).…”

“…Other methods to synthesize AgNPs and AgNPrisms are based on the chemical reduction of silver ions [23][24][25]. Several studies [10,23,[25][26][27] propose the use of a reducing agent to produce the Ag seeds (e.g., sodium borohydride, NaBH 4 ) and the addition of a capping agent to promote AgNP stabilization (e.g., trisodium citrate (TSC); polyvinylpirrolidine (PVP); and dextran). For example, Sun et al [28] indicated that Ag triangular nanoplates can be produced from spherical 3.5-nm AgNPs previously synthesized by reducing Ag + ions in the presence of NaBH 4 , PVP, and sodium citrate.…”