Impact of the Functional Coating of Silver Nanoparticles on their In Vivo Performance and Biosafety

OBJECTIVE AND SIGNIFICANCE

Silver nanoparticles (AgNPs) have become an interesting therapeutic modality and drug delivery platform. Herein, we aimed to investigate the impact of functional coating on the in vivo performance of AgNPs as an economic and scalable method to modulate their behavior.

METHODS

AgNPs were coated with chitosan (CHI) as a model biopolymer using a one-pot reduction-based method, where CHI of two molecular weight ranges were investigated. The resultant CHI-coated AgNPs (AgNPs-CHI) were characterized using UV-VIS spectroscopy, DLS, and TEM. AgNPs were administered intravenously to rats and their biodistribution and serum levels of hepato-renal function markers were monitored 24 h later compared to plain AgNO₃ as a positive control.

RESULTS

UV-VIS spectroscopy confirmed the successful coating of AgNPs with CHI. DLS revealed the superiority of medium molecular weight CHI over its low molecular weight counterpart. AgNPs-CHI demonstrated a semi-complete clearance from the systemic circulation, a liver-dominated tissue tropism, and a limited renal exposure. On the other hand, AgNO₃ was poorly cleared from the circulation, with a relatively high renal exposure and a non-specific tissue tropism. AgNPs-CHI were well-tolerated by the liver and kidney without signs of toxicity or inflammation, in contrary with AgNO₃ which resulted in a significant elevation of Creatinine (CRE), Urea, and Total Protein (TP), suggesting a significant nephrotoxicity and inflammation.

CONCLUSIONS

Functional coating of AgNPs with CHI substantially modulated their in vivo behavior, promoting their hepatic selectivity and biotolerability, which can be invested in the development of drug delivery systems for the treatment of liver diseases.

An ultrasensitive "mix-and-detect" kind of fluorescent biosensor for malaoxon detection using the AChE-ATCh-Ag-GO system

Malaoxon, a highly toxic metabolite of malathion, can lead to severe harm or death if ingested. This study introduces a rapid and innovative fluorescent biosensor that relies on acetylcholinesterase (AChE) inhibition for detecting malaoxon using Ag-GO nanohybrid. The synthesized nanomaterials (GO, Ag-GO) were evaluated with multiple characterization methods to confirm their elemental composition, morphology, and crystalline structure. The fabricated biosensor works by utilizing AChE to catalyze the substrate acetylthiocholine (ATCh), which generates positively charged thiocholine (TCh) and triggers citrate-coated AgNP aggregation on the GO sheet, leading to an increase in fluorescence emission at 423 nm. However, the presence of malaoxon inhibits the AChE action and reduces the production of TCh, resulting in a decrease in fluorescence emission intensity. This mechanism allows the biosensor to detect a wide range of malaoxon concentrations with excellent linearity and low LOD and LOQ values of 0.001 pM to 1000 pM, 0.9 fM, and 3 fM, respectively. The biosensor also demonstrated superior inhibitory efficacy towards malaoxon compared to other OP pesticides, indicating its resistance to external influences. In practical sample testing, the biosensor displayed recoveries of over 98% with extremely low RSD% values. Based on the results obtained from the study, it can be concluded that the developed biosensor has the potential to be used in various real-world applications for detecting malaoxon in food, and water samples, with high sensitivity, accuracy, and reliability.

Hierarchical Assembly of Nanodimensional Silver-Silver Oxide Physical Gels Controlling Nosocomial Infections

Microbial infections originating from medical care facilities are raising serious concerns across the globe. Therefore, nanotechnology-derived nanostructures have been investigated and explored due to their promising characteristics. In view of this, silver-based antimicrobial hydrogels as an alternative to antibiotic-based creams could play a crucial role in combating such infections. Toward this goal, we report a simple method for the synthesis and assembly of silver nanoparticles in a biopolymer physical gel derived from Abroma augusta plant in imparting antimicrobial properties against nosocomial pathogens. Synthesized silver nanoparticles (diameter, 30 ± 10 nm) were uniformly distributed inside the hydrogel. Such synthesized hydrogel assembly of silver nanoparticles dispersed in the biopolymer matrix exhibited hemocompatibility and antimicrobial and antibiofilm characteristics against nosocomial pathogens. The developed hydrogel as a surface coating offers reduced hardness and modulus value, thereby minimizing the brittleness tendency of the gel in the dried state. Hence, we believe that the hierarchical assembly of our hydrogel owing to its functional activity, host toxicity, and stability could possibly be used as an antimicrobial ointment for bacterial infection control.

Mild Synthesis of Copper Nanoparticles with Enhanced Oxidative Stability and Their Application in Antibacterial Films

Copper nanoparticles possess unique physical and chemical properties; however, their application is often restricted, owing to their tendency to oxidize. In this work, we prepared copper nanoparticles with enhanced oxidative stability via a simple and low-cost method, where a modified starch was used as an environmentally friendly reducing agent and biocompatible polyethylenimine was used as a stabilizer. The prepared copper nanoparticles could be stored in air for at least 6 months without any oxidation in a dried state. Interestingly, our synthesis could even be performed at room temperature with a longer reaction time. We used various characterization methods to study the reaction mechanism. The prepared copper nanoparticles were further uniformly doped into an agar film, and this composite showed excellent bacterial killing efficiency, owing to the antibacterial properties of the copper nanoparticles. Our composite film shows potential for various clinical applications, such as wound dressing materials.

Rapid determination of atrazine in apple juice using molecularly imprinted polymers coupled with gold nanoparticles-colorimetric/SERS dual chemosensor

Rapid and reliable determination of atrazine, a common chemical contaminant, in agri-foods is highly necessary. We reported a novel dual-chemosensor coupling, a separation [molecularly imprinted polymers (MIPs)], an instrumental-free detection [gold nanoparticles (AuNPs)-based colorimetric assay] and an instrument-based quantification [surface enhanced Raman spectroscopy (SERS)] method for high-throughput and sensitive determination of atrazine in apple juice. Used as the selective sorbent for the solid phase extraction, MIPs effectively extracted atrazine from apple juice with high recoveries (∼93%). AuNPs of different sizes (large; medium; and small) performed differently in the two analytical methods. Large-AuNPs provided the highest sensitivity in colorimetric analysis (<0.01 mg L^-1), while medium-AuNPs achieved the lowest limit of detection (0.0012 mg L^-1) and quantification (0.0040 mg L^-1) in SERS analysis. With minor modifications, protocols for both analytical methods can rapidly detect and/or quantify atrazine in different food products complying with the Health Canada regulation (0.005 mg L^-1).

Phytofunctionalized silver nanoparticles: green biomaterial for biomedical and environmental applications

Variegated physicochemical routes with emerging modifications have been adopted and reported for silver nanoparticle synthesis for centuries. Nano-biotechnology aimed at the synthesis of nanomaterials, including silver nanoparticles, through utilization of biological media has acquired an auspicious role in science for human welfare. Despite recurrent nanoscale researches on physicochemical routes, coeval stages are predominated by greener methods in silver nanoparticle synthesis for the utilization of its inherent toxicity and exceedingly smaller sizes for biological and environmental applications. One of the principles of green routes for silver nanoparticle synthesis is reduction and stabilization via phytochemicals extracted from plants in a one-pot protocol of phytofunctionalization. Plants are preferred for their abundant availability, environmental non-toxicity and economical favorability and chiefly for the ease of aptness, unlike microbial pathways having tedious requirements of cellular culture maintenance conditions. The present work reviewed the most recent milestones set in the selection of types and parts of plants and optimized synthetic conditions employed in the fabrication of silver nanoparticles, in addition to quantitative and qualitative characterization. Furthermore, the use of phytofunctionalized silver nanoparticles for microbial growth inhibition and environmental remediation was also studied. Through the meticulous review of literature, potential applications were highlighted, which can provide researchers with a plethora of avenues for future investigations for remediation of the environment, in terms of both combating pathogenic microbes and environmental detoxification.

Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe₃O₄@mSiO₂@MIPs) as recognition elements. Using Fe₃O₄ as supporting core, mesoporous SiO₂ as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe₃O₄@mSiO₂@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe₃O₄@mSiO₂@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe₃O₄@mSiO₂@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe₃O₄@mSiO₂@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe₃O₄@mSiO₂@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

Palladium nanoparticle formation processes in fluoropolymers by thermal decomposition of organometallic precursors

Palladium nanoparticles were synthesized directly in solid fluoropolymer films by thermal decomposition of a palladium acetylacetonate precursor molecularly infused in the fluoropolymer matrix.

Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods

In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).