Morphology, Aggregation Properties, Cytocompatibility, and Anti-Inflammatory Potential of Citrate-Stabilized AuNPs Prepared by Modular Ultrasonic Spray Pyrolysis

Abstract

Ultrasonic Spray Pyrolysis (USP) possesses a great potential for production of higher quantities of gold nanoparticles (AuNPs), thus overcoming the problem of batch-to-batch variations in their properties. Recently, we demonstrated that USP with an additional evaporation chamber (modular USP) led to a better size control of AuNPs. However, their morphology, stability, toxicity, and immunomodulatory properties have not been investigated completely. Here, two types of spherical AuNPs were produced by using different USP parameters, followed by their stabilization in Na-citrate solution. No significant changes in their size, agglomeration, andz-potential occurred 3 months after their initial production in citrate solution. However, the conditioning of AuNPs in serum-containing cell culture media for 24 h induced an increase in the AuNPs’ hydrodynamic size and a red shift in their Surface Plasmon Resonance, pointing to their instability in biological media. Cytocompatibility tests showed that the produced AuNPs were internalized by L929 cells and primary human monocytes and were not cytotoxic at the concentrations lower than 200 μg/mL, but they exhibited antiproliferative and anti-inflammatory effects, respectively. AuNPs reduced the percentage of CD14+CD16+but not CD14lowCD16+monocytes in vitro and reduced the expression of CD86, HLA-DR, TNF-α, and IL-12/IL-23 by these cells. These results indicate that the anti-inflammatory effects of citrate-capped AuNPs produced by modular USP could be beneficial for their application in the treatment of inflammatory conditions.

The Effect of Stabilisation Agents on the Immunomodulatory Properties of Gold Nanoparticles Obtained by Ultrasonic Spray Pyrolysis

“…The increase in hydrodynamic size of PEG-GNPs and PVP-GNPs as compared to SC-GNPs, as well as the increase in their SPR peak (532 nm), was most probably due to coating of GNPs with the larger polymers PVP and PEG. These data are in accordance with our previous findings on protein coating of SC-GNPs in cell culture medium [29]. In contrast, the increase in c-GNPs' hydrodynamic size pointed to their partial agglomeration, which was also followed by the loss of SPR in UV-vis analysis.…”

“…Alternatively, GNPs were collected in bottles containing 0.1% Poly-Ethylene Glycol (PEG)-5000 [26] or 1% PVP in water [31], for the generation of PEG-GNPs and PVP-GNPs, respectively. All types of GNPs were characterised as described previously [26,29,32]. Briefly, TEM (CTEM; JEOL 2100) and SEM (FEI Quanta 200 3D) analyses were performed by placing a drop of colloidal suspension of c-GNPs onto a formvar film coated with a layer of carbon, or a lacey formvar film enforced by a heavy coating of carbon copper grid, and dried.…”

“…Previously, we showed that ultrasonic spray pyrolysis (USP) is a great tool for large scale production of GNPs, even from gold scrap [9]. Over the years, we upgraded the production technology of GNPs via USP in different ways [26][27][28][29]. However, a critical step for a successful biomedical application of GNPs is their stability in water solution.…”

Successful Synthesis of Gold Nanoparticles through Ultrasonic Spray Pyrolysis from a Gold(III) Nitrate Precursor and Their Interaction with a High Electron Beam

“…Upon using Au(NO 3 ) 3 as a precursor, the yield efficiency of the USP process was calculated to be 70 % (Section S F), which is significantly higher than the yield efficiency obtained upon using HAuCl 4 as a precursor (<10 %) under the same running conditions . The higher value obtained in the former case can be attributed to the much lower deposition of AuNPs on the transport tubes, impaction, gravitational sedimentation in the transport tubes, diffusion onto the transport tube walls, turbulence, and thermophoresis.…”

“…In the synthesis of AuNPs, tetrachloroaurate in hydrate form [HAuCl 4 ×H 2 O, so‐called gold(III) chloride] is the most commonly reported and used precursor mainly due to its complete solubility in common solvents such as water . However, this precursor causes the in‐growth and transformation of AuNPs into a polydisperse size‐range distribution and also poisons the active surfaces of the AuNPs.…”