Colloidal Nanocomposites Research Articles

Core–Shell Colloidal Nanocomposites for Local Temperature Monitoring during Photothermal Heating

Core–Shell Colloidal Nanocomposites for Local Temperature Monitoring during Photothermal Heating

An efficient chemiluminescent probe based on Ni-doped CsPbBr3 perovskite nanocrystals embedded in mesoporous SiO2 for sensitive assay of L–cysteine

This study presents an efficient chemiluminescence (CL) probe based on perovskite nanocrystals (NCs) for detection of L–cysteine (L–Cys). It consists of nickel–doped CsPbBr3 NCs embedded in the mesoporous SiO2 matrix as CL reagent and cerium (IV) as an oxidant in aqueous environment. The probe was designed for the highly selective determination of L–Cys based on its remarkable enhancing effect on the CL intensity. The colloidal nanocomposite of nickel–doped CsPbBr3 NCs@SiO2 with photoluminescence quantum yield of 58% was fabricated by ligand–assisted re–precipitation method and characterized by using UV–Vis absorption, FT–IR, X–ray diffraction, and transmission electron microscopy. The sensor was utilized to determine L–Cys in the linear concentration range of 20–300 nM with a detection limit of 12.8 nM. Direct chemical oxidation of Ni–doped CsPbBr3 NCs@SiO2 by Ce(IV) was the single cause of the formation of the excited-state NCs and subsequent production of CL. The developed probe provides outstanding selectivity towards L–Cys over structurally related compounds. Accurate determination of L–Cys in human serum samples was achieved without interference, and the results were confirmed by HPLC method.

Colloidal chitosan-silver nanoparticles-fluoride nanocomposite as an antibacterial mouthwash against salivary Streptococcus mutans in orthodontic patients (a randomized clinical trial).

This study aimed to synthesize and characterize colloidal chitosan-silver nanoparticles-fluoride nanocomposite (CCAgNPF) and evaluate its efficacy compared to chlorhexidine on salivary Streptococcus mutans in orthodontic patients. AgNPs stabilized with chitosan were synthesized by chemical reduction of AgNO3. The nanoparticles were characterized with SEM, FTIR, DLS and ICP-OES. The MIC and MBC against S. mutans and IC50 concentration of CCAgNPF were obtained for antibacterial and cytotoxicity evaluations, respectively. For the clinical study, a total of 45 orthodontic patients were divided into three groups of 15 and used the following mouthwashestwice a day for 1 month: CCAgNPF, chlorhexidine 0.2% and the combination of these mouthwashes. The colony count of salivary S. mutans was evaluated before and after using the mouthwashes. The data were analyzed using One-way ANOVA and Tukey's test. Stabilized AgNPs were spherical with a diameter of 25.3 ± 3.3 nm. The MIC, MBC and IC50 of CCAgNPF were 4.42, 8.85 and 18.89 µg/ml. All mouthwashes reduced the salivary S. mutans of the orthodontic patients, however, no significant difference was found between the efficacy of CCAgNPF and chlorhexidine (P-value > 0.05). The best results were achieved by the combination of CCAgNPF and chlorhexidine mouthwashes (P-value < 0.05). The CCAgNPF and its combination with chlorhexidine present potent bactericidal, biocompatible and effective anti-carious mouthwashes for orthodontic patients. This study proved CCAgNPF as an antibacterial mouthwash with lower cytotoxicity and side effects for patients undergoing orthodontic treatments to maintain oral hygiene and reduce salivary S. mutans.

تحسين الخصائص البصرية لأوكسيد القصدير النانوي في بوليمر بولي فينيل الكحول الغروي المحضر بطريقة الاستئصال بالليزر

المركبات النانوية هي مواد مناسبة لتلبية الطلبات الناشئة الناتجة عن التقدم في العلوم والتكنولوجيا. المكونات ذات الهياكل الجديدة و الكفاءة الافضل مقارنة بالمكونات المعالجة تقليديًا مطلوبة للتقدم التكنولوجي. في هذا البحث , يمكن إنشاء مركبات نانوية غروية غير عضوية من البوليمر باستخدام الاستئصال بالليزر النبضي لجسيمات أكسيد القصدير النانوية في بوليمر البولي فينيل الكحول كمضيف. تم استخدام الخصائص البصرية وأطياف الامتصاص للنظر في الخصائص البصرية للمركب النانوي. تم قياس فجوة الطاقة (Eg) ، وتم تحديد الانتقال غير المباشر لقيم بوليمر بولي فينيل الكحول النقي لتكون 5 الكترون . فولت و 3.5 الكترون . فولت للمركب النانوي PVA-SnO2. تم قياس العينات لمعامل الانقراض (k) ، معامل الانكسار (n)، وثابت العزل الكهربائي. انخفض ثابت العزل الكهربائي للمركبات النانوية مع زيادة معامل الامتصاص ، معامل الانكسار ، ومعامل الخمود. تتمتع المركبات النانوية بقدرة امتصاص عالية في منطقة الأشعة فوق البنفسجية ويمكن استخدامها لتغطية المواد لتطبيقات الحماية من الإشعاع.

Apoptosis-induced treatment for ovarian cancer from self-assembled nanocomposites of Fe3O4 nanoparticles and porous organic cages

HypothesisOvarian cancer is one of the most common tumors in gynecology and imposes a heavy burden on patients and their families. Fe3O4 nanoparticles are one of the few nanomaterials approved by the FDA for clinical use, which has been widely used in the diagnosis and treatment of tumor. ExperimentsThe aqueous colloids made from hydrophobic building blocks were fabricated through an oil-in-water emulsion confined assembly strategy. In vitro, the proliferation, migration, invasion of SKOV3 cell after the treatment of iron oxide based assemblies were detected using Test-EdU assay and wound-healing assay. The ovarian cancer of the Nude Mice model was used to investigate the anti-cancer effect of Fe3O4 assemblies and Fe3O4-CC3 co-assemblies in vivo. FindingsThe applied nanocomposites inhibited ovarian cancer cells by CytC/caspase-3 pathway. The results in vivo revealed that treatment of nanocomposites significantly restrained the growth of subcutaneous transplantation tumor in Ovarian Cancer of the Nude Mice model. Our study demonstrated that colloidal nanocomposites assembled from Fe3O4 nanoparticles and porous organic cages inhibits cancer progression and induces apoptosis via caspase pathway. The effect of Fe3O4-CC3 co-assemblies is more profound due to their better contact with the biological matter.

Physicochemical robustness of pulse laser ablated silver-copper nanocomposoites against varied bacterial strains

Nanocomposites (NCs) of inorganic materials with controlled physicochemical characteristics became beneficial for diverse biomedicine and pharmacology applications. Thus, some new types of crystalline spherical silver (Ag)/copper (Cu) nanocomposites (Ag–CuNCs) were made at various laser fluences (ranged from 0 to 14.15 ± 3.9 J cm−2) using the pulsed laser ablation in liquid (PLAL) approach and characterized for the first time. The structures, morphologies, optical and bactericidal properties of these colloidal NCs were determined and the results for the best sample are presented. These NCs showed distinct surface plasmon resonance absorption bands at 402 and 580 nm accompanied by a blue shift. FTIR spectra verified the dispersion of pure Ag–CuNCs in deionized water and XRD pattern confirmed their crystalline nature. EDX analysis of samples confirmed their high purity with appropriate elemental distribution. HRTEM image of the optimum sample exhibited the presence of spherical Ag–CuNCs of mean diameter ≈ 6 ± 1.3 nm and lattice spacing of 0.073 nm and 0.155 nm. Model simulated optimized structure of Ag–CuNCs reaffirmed their stability and chemically reactive HOMO-LUMO isopotential surface. The antibacterial potential of the produced Ag–CuNCs was evaluated using the inhibition zone diameter (IZD) and optical density (at 600 nm) measurements. The optimum Ag–CuNCs prepared at 14.15 ± 3.9 J cm−2 when tested against E. coli, P. aeruginosa, B. subtilis and S. aureus bacteria showed the IZD of 23, 24, 21 and 22 mm, respectively. It was shown that by tuning the laser fluence, the physicochemical and bactericidal attributes of the proposed Ag–CuNCs can be customized, that may have significant implications for potential uses in nanomedicine.

Nanocomposite colloids prepared by the Ouzo effect

HypothesisThe organization of nanoparticles within nanocomposite colloids can imbue added functionality to these suprastructures. We hypothesize that the arrangement of nanoparticles in nanocomposite colloids can be systematically controlled by inducing co-precipitation of oil and a hydrophilic polymer in the presence of nanoparticles with a range of wetting properties. This process will produce oil core/polymer shell nanocapsules with nanoparticles strategically positioned within the suprastructures. ExperimentsCoprecipitation of oil and polymer in the presence of nanoparticles is performed in glass capillary microfluidics. Silica nanoparticles of varying surface properties and morphology are used to investigate the relationship between nanoparticle wetting properties and nanocolloid morphology. The features of the nanocomposites formed are investigated using electron microscopy, sessile drop, and zeta potential measurements. FindingsWhen spherical nanoparticles with wetting properties ranging from hydrophilic to hydrophobic are used, the nanocomposite morphologies formed range from nanoparticles partially engulfed in the polymer shell to nanoparticles embedded in the oil core of the nanocapsule. The number of nanoparticles introduced in the nanocomposite is adjusted by changing their concentration in the precursor solution. The structure of nanocolloids formed with non-spherical or hollow silica nanoparticles depends on their wetting properties.

A Hyperbranched Polyol Process for Designing and Manufacturing Nontoxic Cobalt Nanocomposite.

A method for the design and synthesis of a metallopolymer composite (CoNP) based on cobalt nanoparticles using the hyperbranched polyol process was developed. It was shown that hyperbranched polyester polyols in a melted state can be both a reducing agent and a stabilizer of metal nanoparticles at the same time. The mechanism of oxidation of hyperbranched polyol was studied using diffuse reflectance IR spectroscopy. The process of oxidation of OH groups in G4-OH started from 90 °C and finished with the oxidation of aldehyde groups. The composition and properties of nanomaterials were determined with FT-IR and UV-Vis spectroscopy, Nanoparticle Tracking Analysis (NTA), thermogravimetric analysis (TG), powder X-ray diffraction (XRD), NMR relaxation, and in vitro biological tests. The cobalt-containing nanocomposite (CoNP) had a high colloidal stability and contained spheroid polymer aggregates with a diameter of 35-50 nm with immobilized cobalt nanoparticles of 5-7 nm. The values of R2 and R1 according to the NMR relaxation method for CoNPs were 6.77 mM·ms-1 × 10-5 and 4.14 mM·ms-1 × 10-5 for, respectively. The ratio R2/R1 = 0.61 defines the cobalt-containing nanocomposite as a T1 contrast agent. The synthesized CoNPs were nonhemotoxic (HC50 > 8 g/mL) multifunctional reagents and exhibited the properties of synthetic modulators of the enzymatic activity of chymosin aspartic proteinase and exhibited antimycotic activity against Aspergillus fumigatus. The results of the study show the unique prospects of the developed two-component method of the hyperbranched polyol process for the creation of colloidal multifunctional metal-polymer nanocomposites for theranostics.

On the absence of structure factors in concentrated colloidal suspensions and nanocomposites.

Small-angle scattering is a commonly used tool to analyze the dispersion of nanoparticles in all kinds of matrices. Besides some obvious cases, the associated structure factor is often complex and cannot be reduced to a simple interparticle interaction, like excluded volume only. In recent experiments, we have encountered a surprising absence of structure factors (S(q) = 1) in scattering from rather concentrated polymer nanocomposites (Genix et al. in ACS Appl Mater Interfaces 11(19):17863-17872, 2019). In this case, quite pure form factor scattering is observed. This somewhat "ideal" structure is further investigated here making use of reverse Monte Carlo simulations in order to shed light on the corresponding nanoparticle structure in space. By fixing the target "experimental" apparent structure factor to one over a given q-range in these simulations, we show that it is possible to find dispersions with this property. The influence of nanoparticle volume fraction and polydispersity has been investigated, and it was found that for high concentrations only a high polydispersity allows reaching a state of S = 1. The underlying structure in real space is discussed in terms of the pair-correlation function, which evidences the importance of attractive interactions between polydisperse nanoparticles. The calculation of partial structure factors shows that there is no specific ordering of large or small particles, but that the presence of attractive interactions together with polydispersity allows reaching an almost "structureless" state.

Emulsion polymerized styrene acrylic/nanocellulose composite coating to improve the strength and hydrophobicity of kraft paper

Improving the mechanical and water repelling property of kraft paper will extend its use for packaging application. In this work, we developed a cellulose nanofiber (CNF)-based colloidal polymer nanocomposite that was used as coating for improving those properties of kraft paper. In this case, the polymer latex was obtained by the mini-emulsion copolymerization of styrene (St), 2-ethyl hexyl acrylate (EHA) initiated by ammonium persulfate. The CNFs were incorporated into the styrene-acrylic copolymer matrix by the in-situ polymerization and ex-situ mixing process keeping the CNF concentration up to 1.0 wt%. All the latexes showed particle size below 100 nm and excellent colloidal stability (Zeta potential > −32 mV) for several months. The nanocomposite films showed improved mechanical properties (tensile strength upto 7.8 MPa, elongation upto 1096 %) than the pristine copolymer. The in-situ prepared nanocomposite at 1.0 wt% CNF showed the highest storage modulus. The latex-coated kraft paper showed improved tensile index (31.0–45.1 Nm/g) compared to the uncoated paper (20.3 Nm/g) and also high hydrophobicity (water contact angle ∼120°) for the ex-situ prepared nanocomposites. The results are quite promising to develop paper-based packaging materials using nanocellulose in combination with synthetic polymers.

Osteoregeneration of Critical-Size Defects Using Hydroxyapatite-Chitosan and Silver-Chitosan Nanocomposites.

Bone is a natural nanocomposite composed of proteins and minerals that can regenerate itself. However, there are conditions in which this process is impaired, such as extensive bone defects and infections of the bone or surrounding tissue. This study evaluates the osteoregenerative capacity of bone grafting materials in animals with induced bone defects. Colloidal chitosan dispersion nanocomposites, nanohydroxyapatite−chitosan (NHAP-Q) and nanosilver−chitosan (AgNP-Q), were synthesized and characterized. Non-critical-size defects in Wistar rats were used to evaluate the material’s biocompatibility, and critical-size defects in the calvarias of guinea pigs were used to evaluate the regenerative capacity of the bones. Moreover, the toxicity of the nanocomposites was evaluated in the heart, liver, spleen, kidneys, and skin. Histological, radiographic, and electron microscopy tests were also performed. The results showed that neither material produced pathological changes. Radiographic examination showed a significant reduction in defects (75.1% for NHAP-Q and 79.3% for AgNP-Q), angiogenesis, and trabecular formation. A toxicological assessment of all the organs did not show changes in the ultrastructure of tissues, and the distribution of silver was different for different organs (spleen > skin > heart > kidney > liver). The results suggest that both materials are highly biocompatible, and AgNP-Q achieved similar bone regeneration to that reported with autologous bone. The main research outcome of the present study was the combination of two types of NPs to enhance antimicrobial and osteoregeneration activities. These colloidal chitosan dispersions show promise as future biomaterials in the medical field for applications in fast-healing fractures, including broken bones in the oral cavity and hip replacement infections.

Analytical effective thermal conductivity model for colloidal porous composites and nanocomposites based on novolac/graphene oxide aerogels

Analytical effective thermal conductivity model for colloidal porous composites and nanocomposites based on novolac/graphene oxide aerogels

Nanocomposite Polymer Colloids Prepared via Emulsion Polymerization and Stabilized Using Polydopamine-Coated Silica Particles.

Polymer/inorganic colloidal nanocomposites can be prepared via Pickering emulsion polymerization (PEP); however, this process usually requires the use of surfactants, auxiliary comonomers, and volatile organic compounds. Herein, we report a versatile and efficient method for synthesizing stable monodisperse polymer/silica colloidal nanocomposite particles via PEP. First, silica nanoparticles were modified by depositing a multifunctional polydopamine (PDA) film. The outermost PDA film could enhance the precipitation of oligomeric polymer radicals on the silica surface, which is crucial for the preparation of stable polymer/inorganic colloidal nanocomposites via PEP. Notably, this PDA modification approach can employ different initiator systems, such as cationic initiators and redox initiator couples, and can be applied to various monomers and monomer pairs (St, St/nBA, MMA, MMA/nBA, Vac, Vac/nBA). The influence of the concentration and size of polydopamine-coated silica (SiO2@PDA) on the colloidal nanocomposite was investigated. Increasing the diameter of SiO2@PDA and decreasing the concentration of SiO2@PDA both lead to the formation of larger nanocomposite particles. Considering its wide applicability, the proposed PDA modification approach can be applied to other functional inorganic particles to prepare multifunctional polymer/inorganic nanocomposite particles.

Parameter configuration of the electrical spark discharge method for preparing graphene copper nanocomposite colloids and the analysis of product characteristics.

The electrical spark discharge method was used to prepare graphene copper nanocomposite (GNS-Cu) colloids under normal temperature and pressure. Cu and graphite were mixed in deionized water at a Cu : C mass ratio of 9 : 1 (99% purity), and the mixture was used to produce composite rods as the electrodes for spark machining. An electrical discharge machine with five settings of pulse cycle turn-on and turn-off times, namely 10–10, 30–30, 50–50, 70–70, and 90–90 μs, was used to prepare five different types of GNS-Cu colloids. The ultraviolet-visible spectroscopy results revealed that the highest absorbance (2.441) was observed when the turn-on and turn-off times were 30–30 μs, indicating that this configuration was most efficient for preparing GNS-Cu colloids. Transmission electron microscopy and X-ray diffraction analysis were also conducted to examine the surface characteristics and crystal structure of GNS-Cu colloids. The transmission electron microscopy results revealed that Cu particles in the GNS-Cu colloids were located within or on top of graphene sheets. The Cu particle size varied with the discharge efficiency, and the lattice spacing of the Cu particles was approximately 0.218 nm. The results of X-ray diffraction analysis revealed that no byproducts were formed from the preparation of GNS-Cu colloids, which had complete crystal structures.

Study of stability and antimicrobial activity of colloidal Ag/SiO2 nanocomposites

Ag/SiO2 colloidal nanocomposites (NCs) were synthesised by the chemical reduction of silver ions on a silica surface; NaBH4 was used as a reducing agent, while chitosan served as a stabiliser. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) results of Ag/SiO2 showed a high-density distribution of silver nanoparticles on the silica surface. The influence of pH, ionic concentrations on the stability of Ag/SiO2 colloidal NCs was investigated. Ag/SiO2 colloidal NCs were stable in a wide range of pH values (3–10) and the presence of cations (Mg2+ 25 mM, Ca2+ 15 mM, Fe2+ 1 mM, Fe3+ 0.8 mM). Furthermore, the antimicrobial activity of Ag/SiO2 colloidal NCs against Ralstonia solanacearum 15 (R. solanacearum 15), Bipolaris oryzae (B. oryzae) was evaluated. The minimum inhibitory concentration (MIC) of Ag/SiO2 colloidal NCs for R. solanacearum 15 was 10 ppm, two times lower than that of silver nanoparticles (AgNPs) at 20 ppm, which were prepared by the same route. The inhibitory rate of Ag/SiO2 colloidal NCs against B. oryzae was 99.3% higher than the inhibitory rate of AgNPs 80.4% at the same Ag concentration of 32 ppm. Therefore, Ag/SiO2 colloidal NCs with high antimicrobial activity and stability in wide range pH and ionic strength are a promising pesticide in agriculture.

Loading of apigenin extracted from parsley leaves on colloidal core-shell nanocomposite for bioavailability enhancement

Apigenin, as a bioactive compound, exhibits a wide range of health beneficial properties; however, its therapeutic application is limited because of its poor water-solubility and low bioavailability. In the present study, apigenin was isolated and purified from parsley leaves and to enhance its bioavailability, it was loaded on the zein-lecithin nanocomposite, which was fabricated by the antisolvent coprecipitation method. The developed nanocomposite was characterized by DLS, zeta-potential, FTIR, XRD, FE-SEM, and TEM analyses. Under optimum apigenin formulation condition (pH 4, zein:lecithin mass ratio of 1:5 and apigenin dosage of 1.5 mg) the mean particle size, PDI and zeta-potential of the nanocomposite were 132.4 nm, 0.16 and −31.9 mV, while the apigenin loading and encapsulation efficiency were 4.7% and 77.4%, respectively. The developed spherical zein-lecithin nanocomposite had higher apigenin encapsulation efficiency compared to the single nanoparticles of zein and lecithin, and the stability of apigenin significantly improved against sunlight irradiation. Results showed that the synthesized nanocomposite was pH-sensitive where 87% of the encapsulated apigenin could be released from the nanocomposite under acidic pH. Loading of apigenin into the zein-lecithin nanocomposite promoted the cytotoxic effects of apigenin against Saos2 cell lines up to 75.77% in vitro, while no significant side effect on normal fibroblast cells was observed. • Apigenin (Ap) was obtained by purifying ultrasonic extract of parsley leaves. • We developed Ap/zein-lecithin nanocomposite by antisolvent coprecipitation. • Loading of AP on nanocomposite enhanced its photostability. • Ap/Z-L was pH-sensitive and considerable amount of Ap released under acidic pH. • Significant cytotoxicity against Saos2 cell lines was demonstrated.

Preparation of highly colloidal stable Yolk-Shell nanocomposite and its multi-stimuli responsive based on surface aggregation-induced emission (S-AIE)

Multi-stimuli responsive fluorescence probe could pave the way for monitoring more complex environmental changes. Here we prepared multifunctional nanoparticle Fe3O4@SiO2@P(DMAEMA-co-TPEE), which displayed yolk-shell morphology with well-defined polymer brush. With superparamagnetic Fe3O4 component and pH/temperature dual sensitive PDMAEMA polymer brush, the as prepared nanoparticles (YS-NPs) exhibited as multi-stimuli responsive fluorescence probe for real-time visual monitoring of environmental changes such as magnetic field, temperature and pH. Such YS-NPs could also be applied as a sensitive detector for CO2 in aqueous solution. Notably, the solution of YS-NPs showed high colloidal stability during the environmental changes, and surface aggregation-induced emission (S-AIE) was proposed for the aggregation of TPE residue on the surface of YS-NPs.

Anchoring of graphitic carbon nitride on reduced graphene sheets by UV pulsed laser irradiation for augmented photoelectrochemical water splitting

Recently graphitic carbon nitride (GCN) has gained a great significance as it is one of the most suitable materials for large-scale photocatalytic water splitting because, it has a narrow band gap energy, photoelectrochemical stability, non-toxicity, and low-cost production. However, bare GCN is not reliable in terms of its relatively poor intrinsic photoelectrochemical performance as it possesses a low surface area, a high recombination rate of photo-induced charge carriers, and poor adhesion to the current collector. Here, we report a green, and low-cost approach to anchor GCN on reduced graphene oxide (rGO) sheets, forming rGO/GCN colloidal nanocomposite by simply irradiating a GO/GCN dispersion in methanol aqueous solution using a UV laser without further treatment. In contrast with the bare GCN, the synthesized rGO/GCN nanocomposite exhibited a higher tendency of visible light absorption (400-700 nm), a lower recombination rate of photo-induced charge carriers, excellent adhesion on the current collector, and thus higher photoelectrochemical efficiency for water splitting under visible light illumination. The photocurrent density of the rGO/GCN photoanode was enhanced by nine folds (~90 mA cm−2) in alkaline media over that one produced by the bare GCN under the same operating conditions. This study exhibits the feasibility and effectiveness of UV laser irradiation in the synthesis of high-purity rGO-based photocatalytic nanocomposites at room temperature for large-scale photoelectrochemical water splitting.

Distinct optical response of colloidal gold-cinnamon nanocomposites: Role of pH sensitization

Nanocomposites (NCPs) with excellent physical, chemical and optical properties have been broadly used for commercial products and industrial applications. Based on these features of the NCPs, we prepared colloidal gold (Au) and organic cinnamon (Cin) NCPs by laser irradiated Au and Cin targets separately immersed in glass container fulfilled with different pH solutions (5.0 to 8.0). A Q-switched pulse laser ablation in liquid (PLAL) technique was employed to customize morphology, structural and optical characteristics of these grown nanoparticles inside various pH solutions at room temperature. Colloidal solution of gold-cinnamon nanocomposites (Au-Cin NCPs) was characterized via Transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) spectrometer and CIE 1931 chromaticity diagram. TEM image and SAED patters revealed spherical shaped Au-Cin NCPs with a particle diameters of 5.19 ± 1.23 nm and a nanocrystalline face centred cubic (FCC) nucleation. These plasmonic Au-Cin NCPs very strong UV-Vis absorbance bands at (270 nm and 522 nm) and CIE color coordinate (color temperature of 6437.001 K and color purity of 11.9130 %). It is established that the PLAL made-up Au-embedded Cin NCPs may be useful for the formulation of nanobiomedicine drugs.

Improved Synthesis of Ag/SiO₂ Colloidal Nanocomposites and Their Antibacterial Activity Against Ralstonia solanacearum 15.

Ag/SiO₂ colloidal nanocomposites (NCs) were prepared through the semi-continuous chemical reduction of silver ions on a silica surface; NaBH4 was used as a primary reducing agent, while carboxymethyl cellulose (CMC) served as a secondary reductant and a stabilizer at low temperature. Silver nanoparticles (AgNPs) of an average diameter of 3.89±0.18 nm were uniformly and densely dispersed on the SiO₂ surface, forming 218.6-nm-sized Ag/SiO₂ NCs. The zeta potential of the Ag/SiO₂ NCs (-92.6 mV) was more negative than that of silica (-24 mV), indicating their high long-term stability. Furthermore, their proposed formation mechanism was confirmed via Fourier transform infrared spectroscopy. Then, the bactericidal effect of the Ag/SiO₂ was evaluated based on their minimal inhibitory concentration (MIC) against Ralstonia solanacearum 15 (R. solanacearum 15); it was 62.5 ppm, much lower than that of conventional AgNPs (500 ppm). Therefore, these highly stable Ag/SiO₂ colloidal NCs with more effective antibacterial activity than conventional AgNPs are a promising nanopesticide in agriculture.