Microwave-assisted synthesis of Limonia acidissima Groff gum stabilized palladium nanoparticles for colorimetric glucose sensing

Herein, we present a novel microwave-assisted method for the synthesis of palladium nanoparticles (PdNPs) supported by Limonia acidissima Groff tree extract gum. The synthesized PdNPs were characterized using various analytical techniques, including FTIR, SEM, TEM, UV-visible, and powder XRD analyses. TEM and XRD analysis confirmed that the synthesized LAG-PdNPs are highly crystalline nature spherical shapes with an average size diameter of 7-9 nm. We employed these gum-capped PdNPs to investigate their peroxidase-like activity for colorimetric detection of hydrogen peroxide (H2O2) and glucose. The oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2, catalyzed by PdNPs, produces oxidation products quantified at 652 nm using spectrophotometry. The catalytic activity of PdNPs was optimized with respect to temperature and pH. The developed method exhibited a linear range of detection from 1 to 50 µm, with detection limits of 0.35 µm for H2O2 and 0.60 µm for glucose.

Herb Polysaccharide-Based Drug Delivery System: Fabrication, Properties, and Applications for Immunotherapy

Herb polysaccharides (HPS) have been studied extensively for their healthcare applications. Though the toxicity was not fully clarified, HPS were widely accepted for their biodegradability and biocompatibility. In addition, as carbohydrate polymers with a unique chemical composition, molecular weight, and functional group profile, HPS can be conjugated, cross-linked, and functionally modified. Thus, they are great candidates for the fabrication of drug delivery systems (DDS). HPS-based DDS (HPS-DDS) can bypass phagocytosis by the reticuloendothelial system, prevent the degradation of biomolecules, and increase the bioavailability of small molecules, thus exerting therapeutic effects. In this review, we focus on the application of HPS as components of immunoregulatory DDS. We summarize the principles governing the fabrication of HPS-DDS, including nanoparticles, micelles, liposomes, microemulsions, hydrogels, and microneedles. In addition, we discuss the role of HPS in DDS for immunotherapy. This comprehensive review provides valuable insights that could guide the design of effective HPS-DDS.

An efficient biosynthesis of palladium nanoparticles using Bael gum and evaluation of their catalytic and antibacterial activity

We report a facile microwave-assisted synthesis of palladium nanoparticles (PdNPs) using Bael gum (BG) and it's carboxymethylated (CMBG) derivative. The prepared nanoparticles (BG@PdNPs and CMBG@PdNPs) were evaluated for antibacterial and catalytic activity in the reduction of organic dye pollutants. The developed synthetic method is simple, low cost and eco-friendly, wherein the process requires no additional reducing or capping agents. The CMBG was prepared via etherification reaction between BG and monochloroacetic acid using Williamson synthesis method. The PdNPs were synthesized using BG and CMBG as stabilizers and reducing agents. The PdNPs were found to be well dispersed spherical, with the crystalline size of the order of 7-21 nm. The results showed that the CMBG@PdNPs were smaller in size (7 ± 2 nm) than those capped with BG@PdNPs (10 ± 2 nm). The catalytic ability of CMBG@PdNPs was examined for the reduction of Methyl Orange (MO), Methyl Red(MR), and Rhodamine-B (RhB) in the presence of NaBH₄. The results showed that CMBG@PdNPs exhibited a higher catalytic ability than BG@PdNPs. Moreover, it was found that CMBG@PdNPs served several times as a retrievable and reusable catalyst which is stable even after six cycles of reaction. The CMBG@PdNPs and BG@PdNPs showed excellent antibacterial activity. The results indicate that CMBG@PdNPs have greater potential application as a catalyst in the reduction of organic pollutants and antibacterial activity.

Ultra-small and biocompatible platinum nanoclusters with peroxidase-like activity for facile glucose detection in real samples

The highly sensitive glucose detection based on the peroxidase-like properties of nanoclusters has been gained great interest. In this work, Pericarpium Citri Reticulatae polysaccharide (PCRP) stabilized platinum nanoclusters (Pt-PCRP NCs) were prepared by a green method in which potassium tetrachloroplatinate and PCRP were simply mixed without addition of other agents. Platinum nanoclusters (Pt NCs) had ultra-small size of 1.26 ± 0.34 nm. The hydrodynamic size of Pt-PCRP NCs was 29.7 nm, and zeta potential of which was -12.0 mV. Pt-PCRP NCs showed high biocompatibility toward HeLa cells and red blood cells. In addition, Pt-PCRP NCs catalyzed the decomposition of H₂O₂ to produce •OH, which further oxidized colorless 3,3'5,5'-tetramethylbenzidine (TMB) to blue oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB), exhibiting peroxidase-like property. The kinetics followed the Michaelis-Menten equation. More importantly, the colorimetric method for glucose detection using Pt-PCRP NCs had high selectivity and low detection limit for 0.38 μM. The established method based on Pt-PCRP NCs was used to precisely detect glucose detection in human serum, saliva, and sweat. Taken together, the prepared ultra-small and biocompatible Pt-PCRP NCs have good potential glucose applications in clinical diagnosis in the future.

Green synthesis of palladium nanoparticles using lentinan for catalytic activity and biological applications

The green synthesis of palladium nanoparticles (Pd NPs) for catalysis and biological applications has been gaining great interest. To replace complex plant extracts, lentinan (LNT) may be a good reducing and stabilizing agent. In this work, a simple and green method using LNT to reduce and stabilize palladium Pd NPs was verified. The resulting LNT stabilized palladium nanoparticles (Pd_n-LNT NPs) were characterized by UV-Vis spectroscopy, DLS, TEM, and XPS. The results indicated that Pd NPs inside of Pd_n-LNT NPs had a small size (2.35–3.32 nm). Pd_n-LNT NPs were stable in solution for 7 days. In addition, Pd_n-LNT NPs had higher catalytic activity towards the reduction of 4-nitrophenol than other catalysts. More importantly, Pd_n-LNT NPs had negligible cytotoxicity towards cells and showed good antioxidant activity. Taken together, the prepared Pd_n-LNT NPs have great potential bio-related applications.

Lentinan stabilized palladium nanoparticles had high catalytic activity, negligible cytotoxicity and good antioxidant activity.

Biocompatible Dendrimer-Encapsulated Palladium Nanoparticles for Oxidation of Morin

Development of highly efficient catalysts to expedite the degradation of organic dyes has been drawing great attention. The aggregation of catalysts reduces the accessibility of catalytic centers for organic dyes and therefore decreases their catalytic ability. Herein, we report a facile method to prepare highly biocompatible and stable dendrimer-encapsulated palladium nanoparticles (Pd n -G5MCI NPs), which exhibit high catalytic efficiency for oxidation of morin. The biocompatible dendrimers were prepared via surface modification of G5 polyamidoamine (G5 PAMAM) dendrimers using maleic anhydride and l-cysteine. Then, they were incubated with disodium tetrachloropalladate, followed by reduction using sodium borohydride to generate Pd n -G5MCI NPs. Transmission electron microscopy results demonstrated that palladium nanoparticles (Pd NPs) inside Pd n -G5MCI had small diameters (1.77-2.35 nm) and monodisperse states. Dynamic light scattering results confirmed that Pd n -G5MCI NPs had good dispersion and high stability in water. Furthermore, MTT results demonstrated that Pd n -G5MCI NPs had high biocompatibility. More importantly, Pd n -G5MCI NPs successfully catalyzed the decomposition of H2O2 to the hydroxyl radical (•OH), and the generated •OH quickly oxidized morin. This reaction kinetics followed pseudo-first-order kinetics. Apparent rate constant (k app) is an important criterion for evaluating the catalytic rate. The concentrations of Pd n -G5MCI NPs and H2O2 were positively correlated with k app, whereas the correlation between the concentration of morin and k app was negative. The prepared Pd n -G5MCI NPs have great potential to catalyze the degradation of organic dyes in bio-related systems in the future.

Ultra-small biocompatible jujube polysaccharide stabilized platinum nanoclusters for glucose detection

Jujube polysaccharide-stabilized platinum nanoclusters were used for the sensitive detection of glucose concentrations in serum and saliva.