Synthesis, Characterization, and Antimicrobial Activity of Near‐IR Photoactive Functionalized Gold Multibranched Nanoparticles

Abstract

Surface‐modified gold multibranched nanoparticles (AuMs) were prepared by simple chemical reduction of gold chloride aqueous solution followed by in situ modification by using water‐soluble arenediazonium tosylates with different functional organic groups. Chemical and morphological structures of the prepared nanoparticles were examined by using transmission electron and scanning electron microscopies. The covalent grafting of organic compounds was confirmed by scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDX) and Raman spectroscopy techniques. Covalent functionalization of nanoparticles significantly expands the range of their potential uses under physiological conditions, compared with traditional non‐covalent or thiol‐based approaches. The antibacterial effect of the surface‐modified AuMs was evaluated by using Escherichia coli and Staphylococcus epidermidis bacteria under IR light illumination and without external triggering. Strong plasmon resonance on the AuMs cups leads to significant reduction of the light power needed kill bacteria under the mild conditions of continuous illumination. The effect of the surface‐modified AuMs on the light‐induced antibacterial activities was founded to be dependent on the grafted organic functional groups.

Ultrasensitive and reproducible SERS platform of coupled Ag grating with multibranched Au nanoparticles

“…The grating structure is screened by the attached AuMs, which indicates the full covering of the pristine surface during the reaction time. 34 It is well known that the proximity of noble metal nanostructures to each other can induce a significant shift of their plasmon resonance wavelength position. 35 With the aim to estimate the mean positions (SPP in the case of Ag grating and LSP in the case of AuMs), as well as their potential shift, resulting from the plasmonic coupling, a series of UV measurements (presented in Fig.…”

“…Then the AuMs were dispersed in 3 mL of water and were purified three times by centrifugation at 5000 rpm for 10 min. 34 For further use, the resultant precipitates were redissolved in deionized water.…”

Enhancement of Surface Plasmon Fiber Sensor Sensitivity Through the Grafting of Gold Nanoparticles

“…AuMs (Au multibranched nanoparticles) were prepared according to the procedure published in [31]. Freshly prepared fibers with Au layer were immersed into a methanol solution of BFDT (5×10 −3 molL −1 ) for 24 h. After incubation, the samples modified by BFDT were washed with methanol and immersed into solutions of AuMs for 24 h. Finally, the samples were cleaned in an ultrasonic bath (in distilled water) and dried under a N 2 flow.…”

Versatile Polypeptide-Functionalized Plasmonic Paper as Synergistic Biocompatible and Antimicrobial Nanoplatform

“…On the other hand, gold nanoparticles exhibit low toxicity [ 8 , 9 ]; however, sometimes their intrinsic size and shape-dependent antibacterial activity seems to be insufficient. To overcome this problem, the surface modification of the plasmonic nanoparticles could be an answer, through use of controlled grafting of different charged molecules facilitating specific binding to the bacterial membrane, and, consequently, generating an increase of their antibacterial activity [ 10 ]. Taking profit of the tunable sizes and shapes, as well as their easy surface functionalization, differently-functionalized gold nanoparticles started to be widely investigated as antibacterial, antifungal, antibiotic film platforms [ 11 ].…”