PEGylated Gold Nanoparticles with Interesting Plasmonic Properties Synthesized Using an Original, Rapid, and Easy-to-Implement Procedure

Abstract

In this letter, we report a new, one-step, rapid, and easy-to-implement method for the synthesis of PEGylated gold nanoparticles (PEG-AuNPs) having a narrow size distribution and very interesting plasmonic properties. Unmodified polyethylene glycol molecules with a molecular weight of 1000 g/mole (PEG1000) have been employed as reducing and capping agents for the synthesis of spherical gold nanoparticles having an average diameter of 35 nm, within a few minutes. The novelty of the herein proposed synthesis method consists in the fact that the synthesis takes place inside of a sealed bottle flask containing aqueous solutions of PEG1000, tetrachloroauric(III) acid (HAuCl4), and NaOH, placed in the center of a microwave oven, capable to provide a very uniform temperature environment. It turned out that, during the very short synthesis procedure (2 minutes), PEG 1000 suffers an oxidative transformation in such a manner that its terminal alcohol groups (-CH2-OH) are transformed in carboxylate ones (-COO−). The as-synthesized PEG-AuNPs possess very interesting plasmonic properties allowing the detection of different molecules by means of SER spectroscopy performed either in liquid droplets or on solid spots. As a consequence of their unique plasmonic properties, the SER spectra acquired using this new class of nanoparticles on different molecules of interest (methylene blue, rhodamine 6G, doxorubicin, and 5-fluorouracil) are highly reproducible, making them ideal candidates for further use as SERS substrates.

Synergistical Use of Electrostatic and Hydrophobic Interactions for the Synthesis of a New Class of Multifunctional Nanohybrids: Plasmonic Magneto-Liposomes

“…Anionic PEGylated gold nanoparticles were synthesized using an original method developed in our laboratory, employing PEG 1000 molecules as both reducing and capping agents [34]. The synthesis method is described in the experimental section.…”

“…A strategy to overcome these issues is found in combining the features of different classes of nano-objects by synthesizing hybrid structures that comprise their functionalities. Over time, our research group has developed several original strategies for the synthesis of biocompatible nanoparticles exhibiting very interesting surface properties by using PEG [31,32,33,34], natural cyclodextrins [35], and plant extracts [36] as reducing agents. Meanwhile, by taking advantage of electrostatic interactions, an original method for the synthesis of PEGylated plasmonic liposomes was reported [37].…”

Gold Nanoparticles: A New Golden Era in Oncology?

“…Another problem related to the efficacy of AuNPs as anticancer agents is their recognition by the immune system, ending with their phagocytosis by the cells of the reticuloendothelial system and clearance from the bloodstream [13,36]. As explained in Section 2.1, to escape fast immune recognition and clearance, AuNPs have been coated with a polyethylene glycol (PEG) layer by a process defined as "PEGylation", which masks the AuNP surface and prevents their recognition by the immune system, prolonging their persistence and activity [37].…”

Theranostic Nanoparticles and Their Spectrum in Cancer

“…Some NPs have innate optical properties like QDs [162] and metallic NPs due to surface plasmon resonance [48,[163][164][165]. QDs nanoparticles labeled with F-Fluoropropionate and functionalized with RGD peptides demonstrate proper optical characteristics for PET imaging of prostate cancer [166].…”