The Use of Capping Agents in the Stabilization and Functionalization of Metallic Nanoparticles for Biomedical Applications

Abstract

The study of nanoparticles (NPs) and their application in different areas of research, including biomedicine, is attracting the attention of researchers worldwide. Numerous investigations published during the last 20 years cover the fabrication of new materials in the nanoscale, and several uses have been proposed. Metallic nanoparticles (MNPs) have generated a high level of interest, based on improved optical, electrical and magnetic properties, ease of manufacturing, small sizes, and easy functionalization. However, when it comes to Biomedicine, particle aggregation, possible toxicity, and the need for effective cell internalization, still demand active investigation. The main strategy to overcome these drawbacks is possibly the use of capping agents to increase the stability of the particles in dispersion, their biocompatibility and functionalization. In this review, important concepts and characteristics of MNPs, are collected and described. The importance of surface coating for biomedical applications of metallic nanoparticles as well as the most used capping agents and metallic nanomaterials, are also discussed. Finally, the text includes examples and essential characteristics for the biomedical use of MNPs, including the consideration of important challenges. Aspects such as relevant biological activity, increased biocompatibility and functionalization potential are among the most desirable attributes of a capping agent.

α-Amino Acids as Reducing and Capping Agents in Gold Nanoparticles Synthesis Using the Turkevich Method

“…A possible solution is using simple green reagents as reducing and capping agents, such as α-amino acids (α-AA). − The advantage of using α-AA as capping agents is that a single molecule offers amino and carboxy groups for conjugating essential biomolecules. They also increase the biocompatibility of nanoparticles they cap and reduce issues associated with using them in biomedical applications, such as size, biodistribution, interaction with immune cells, and induction of inflammation. , The α-AA have also been shown in several studies as efficient reducing agents capable of reducing gold salts in a controlled manner to obtain uniform quasi-spherical gold nanoparticles. − The advantages of using α-AA to reduce gold salts compared to other often used reducing agents, in addition to their advantages mentioned above as capping agents, include their nontoxicity, low price, and availability. Therefore, it is not surprising that many studies have reported using one, − a few, − or all 20 proteinogenic α-AA for synthesizing AuNPs.…”

MoS2 and MoSe2 2D nanosheets-based supramolecular nanostructure scaffold-capped Ag-NPs: exploring their morphological, anti-bacterial, and anticancer properties

“…76 Some innovative efforts include hydrogel-nanocomposites as biomaterials, 77 nano-bio composite polymer hydrogels, 78 gellan gum-based silver nanocomposites for antibacterial properties, 79 as well as stabilization and functionalization of metallic nanoparticles for biomedical applications. 80…”

“…75 Use of SHGels as capping agents have been documented. [76][77][78][79][80] The stabilization and organization of gold nanoparticles through cysteine-functionalized organogelators and the synthesis of various nanoparticle-gel composites under in situ conditions have been explored. 76 Some innovative efforts include hydrogel-nanocomposites as biomaterials, 77 nano-bio composite polymer hydrogels, 78 gellan gum-based silver nanocomposites for antibacterial properties, 79 as well as stabilization and functionalization of metallic nanoparticles for biomedical applications.…”

“…76 Some innovative efforts include hydrogel-nanocomposites as biomaterials, 77 nano-bio composite polymer hydrogels, 78 gellan gum-based silver nanocomposites for antibacterial properties, 79 as well as stabilization and functionalization of metallic nanoparticles for biomedical applications. 80 Inspired by this knowledge, we attempted to synthesize ''green'' Ag-NPs capped by MoX 2 (X = S and Se) 2D nanosheets-dispersed nanocomposite materials and explored the morphological pattern of Ag-NPs based on the nature of nanocomposites. We focused on the bioactivity of newly synthesized Ag-NPs capped by MoX 2 2D nanosheets-based nanocomposite scaffolds.…”

Catalysts Originating from Tailor‐made Metal Ethylene Glycol Carboxylates

“…However, the stabilization of the thus formed NPs has to be facilitated by coordinating protective ligands such as dendrimers, polymers and surfactants, providing electrostatic and/ or steric protection to avoid agglomeration. [54,55] Contrary to these classical methodologies, a single source process was recently introduced by our group using ethylene glycol metal carboxylates of type [L x M(O 2 CCH 2 (OCH 2 CH 2 ) n OMe) m ] y (L x M = (PR 3 ) 2 Cu, (PR 3 )Ag, (PPh 3 )Au, (PR 3 ) 2 Pd, (PR 3 ) 2 Pt, (PR 3 ) 2 (CO) 2 Ru, (PR 3 )Rh; n = 0, 1, 2, 3, 4, 5, 7.33; m = 1, 2; y = 1, 2) and [M(O 2 CCH 2 (OCH 2 CH 2 ) n OMe) m ] (M = Ag, Co, Cu; m, n = 1, 2) (Scheme 1). [56][57][58][59][60][61][62][63][64][65][66][67][68][69] The advantage of this approach is an easy reaction control over the straightforward formation of unique and tailored NPs with no need for both, the addition of reducing agents and stabilizing additives.…”