Surfactant-free Method Research Articles

Effect of Gold Nanostars Plus Amikacin against Carbapenem-Resistant Klebsiella pneumoniae Biofilms.

Simple SummaryCarbapenem-resistant Klebsiella pneumoniae (CR-KP) infection rates represent a challenging treatment since the pipeline for effective antibiotics against this pathogen, such as beta-lactams among others, is practically nil. This study aims to evaluate the antibacterial effect of gold nanostars (GNS) alone or associated with some of the most widely used antibiotics for the treatment of CR-KP strains, i.e., meropenem or amikacin, on both planktonic or free-living and sessile forms. GNS were able to inhibit the planktonic growth of CR-KP at 80 µM, to eradicate the bacterial viability at 160 µM, and were unable to inhibit or eradicate the biofilm growth of this bacterium. GNS gave rise to filamentous bacteria through mechanisms mediated by the inhibition of energy-dependent cytoplasmic proteases. The combination of GNS and amikacin was able to inhibit or even eradicate the CR-KP biofilm. This combination was administered to greater wax moth larvae (Galleria mellonella), and this treatment was found to be tolerated well and to prevent the CR-KP infection. Thus, GNS in combination with amikacin represent a promising anti-CR-KP nanomaterial.(1) Background: Carbapenem-resistant Klesiella pneumoniae (CR-KP) infection rates depict an almost pre-antibiotic scenario since the pipeline for effective antibiotics against this pathogen has been almost entirely depleted. This study aims to evaluate the antibacterial effect of gold nanostars (GNS) alone or associated with some of the most widely used antibiotics for the treatment of CR-KP strains, i.e., meropenem or amikacin, on both planktonic and sessile forms. Additionally, we measured the effect of GNS on cell proliferation and biocompatibility in invertebrate in vivo models. (2) Materials and methods: GNS were made from gold seeds grown using a seeded-growth surfactant-free method assisted by silver ions and functionalized with mercapto-poly(ethylene glycol)amino by ligand exchange. The antimicrobial capacity, effect on cell proliferation, and biocompatibility of the most effective combination was evaluated in a Galleria mellonella model. (3) Results: The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were 80 and 160 µM of GNS for all strains, respectively. The minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were >320 µM of GNS for both. A synergy was found between GNS and amikacin. Larvae administered GNS plus amikacin were found to tolerate the treatment well, which prevented infection. (4) Conclusions: GNS are a promising anti-CR-KP nanomaterial.

A Hierarchical Structure of Flower-Like Zinc Oxide and Poly(Vinyl Alcohol-co-Ethylene) Nanofiber Hybrid Membranes for High-Performance Air Filters.

In this article, we reported a hierarchical structure of flower-like zinc oxide (ZnO) and poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofiber (ZnO@NF) hybrid membranes for high-performance air filters. Monodispersed flower-like ZnO superstructures were fabricated using a template-free and surfactant-free hydrothermal method, and PVA-co-PE nanofiber yarns were prepared using a melt extrusion phase separation approach. The PVA-co-PE nanofiber yarns were subjected to high-speed shearing in a mixed aqueous solution of isopropanol and water to obtain a stably dispersed nanofiber suspension. The ZnO@NF hybrid air filter was obtained by coating the mixture of flower-like ZnO superstructures and the PVA-co-PE nanofiber suspension on the surface of the polypropylene (PP) meltblown nonwoven with the electret charge eliminated. The filtration efficiency of the ZnO@NF hybrid air filter increases with increasing loading amount of the flower-like ZnO superstructures, while the pressure drop decreases. The flower-like ZnO superstructures were incorporated into the nanofiber-interconnected networks, which significantly reduces the pressure drop of the pure PVA-co-PE nanofiber air filter. The filtration efficiency of the ZnO@NF hybrid air filter is much higher than that of PP meltblown nonwoven with eliminated electret charge, solving the hidden problem of electret charge dissipation during the protection process. It is demonstrated that these nanofiber hybrid air filters have great application potential in some special areas such as high-temperature and high-humidity environments.

Efficient and controlled H2 release from sodium formate

A simple and surfactant-free method was successfully employed to construct M16Pd1/C bimetallic nano-materials for direct H2 production by SF decomposition in the presence of acetic acid.

Synthesis and characterization of novel coral spherical bismuth oxide

Bismuth oxide, a widely studied semiconductor material, has been discovered in a variety of forms. Novel coral spherical α-Bi2O3 with a diameter of 2–4 μm was successfully prepared by a simple template-free and surfactant-free hydrothermal method. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission electron scanning microscopy (FESEM), energy dispersive spectroscopy (EDX) and transmission electron microscopy (TEM). The experimental results revealed that the reaction time and the urea concentration could regulate the morphology of Bi2O3, and a possible formation mechanism was proposed based on the results. This study provides a new idea for the morphological synthesis of bismuth oxide.

Surfactant-free synthesis of sub-10 nm Co3O4 in a rotating packed bed and its high catalytic activity for AP pyrolysis

Sub-10 nm Co3O4 nanoparticles with a narrow size distribution are prepared by a surfactant-free liquid precipitation method in a rotating packed bed (RPB) reactor. The mean size of the material is about 8.5 nm, and is the smallest among previous reports via surfactant-free liquid precipitation. The growth mechanisms show that the sizes of Co3O4 nanoparticles inherit from the precursory Co(OH)2. Compared to the traditional stirred tank reactor, RPB can enhance the nucleation of Co(OH)2 through enhanced micro-mixing, which leads to thinner and more uniform products. As-prepared Co3O4 can show enhanced catalytic performance for ammonium perchlorate (AP) decomposition. The peak temperatures of AP decomposition reduce to 296.8 °C, 291.8 °C, 290.0 °C, and 286.6 °C by adding 2 wt% 22.6 nm, 15.0 nm, 10.9 nm, and 8.5 nm of Co3O4 nanoparticles, respectively. Density functional theory (DFT) calculations and thermogravimetry coupled with mass spectrometry (TG-MS) analysis reveal that the size-dependent catalytic activity of Co3O4 for AP decomposition origin from varied O2 activation ability and NH3 adsorption capacity at the edge and corner sites.

Fabrication of sea urchin-like Au@SiO2 nanoparticles SERS substrate for the determination of malachite green in tilapia

The quantitative determination of malachite green (MG) is of great importance in aquatic product safety. Although it has been testifying that sea urchin-like gold nanoparticles (SGNPs) have good enhancement effect, the practical application remains challenging for surface-enhanced Raman spectroscopy (SERS) due to poor stability. Here, sea urchin-like Au@SiO2 nanoparticles (SG@SiO2 NPs) is designed and synthesized through a controllable and surfactant-free hydrothermal method to improve its stability. The morphology of SG@SiO2 NPs and the SiO2 shell thickness were adjusted to obtain good SERS performance. The SERS signal intensity was linear for MG, crystal violet (CV) and methylene blue (MB) at 1619 cm−1, 1623 cm−1 and 1627 cm−1 over the concentration range of 10−5-10−9 M, 10−5-10−9 M and 10−5-10−8 M, respectively. The substrate was easily used for MG detection with limit of detection (LOD) as low as 1.5 × 10−9 M. The recovery of MG added to several tilapia fillets samples at different concentrations ranged from 90 % to 110 %. Results indicated that SERS substrate can be used for the determination of trace amounts of MG in tilapia and demonstrated the potential of SG@SiO2 NPs SERS substrate in food analysis fields.

Synthesis and characterization of double molecular imprinted nanoparticles and investigation to adsorption of respiratory drugs

ABSTRACT In this study, novel double molecular imprinted nanoparticles (DMIP nanoparticles) with multi-functional monomers were prepared for adsorption of salmeterol xinafoate (SAM) and fluticasone propionate (FLU) drugs. For this purpose, SAM and FLU imprinted poly (2-hydroxyethyl methacrylate-N-methacryloyl-(L)-alanine-N-methacryloyl-(L)-histidine) [p(HEMA-MAAL-MAH)] nanoparticles were synthesized by surfactant-free emulsion polymerization method. After the characterization, adsorption conditions were optimized, and the adsorption kinetics parameters were also calculated. In the selectivity experiments, budesonide (BS) and formoterol fumarate (FF) drugs were used as competitive drugs. These novel development DMIP nanoparticles have the potential for use in many different areas, for purposes such as drug release, separation, and purification.

Influence of Fe, La, Zr, Ce, and Ca on the catalytic performance and coke formation in dry reforming of methane over Ni/MgO.Al2O3 catalyst

The catalytic and structural properties of the mesoporous nanocrystalline 10 wt.% Ni–MeOx (Me= Fe, La, Zr, Ce, Ca)-MgAl2O4 catalysts were investigated in dry reforming of methane. The catalysts were synthesized simultaneously via a simple and novel surfactant-free self-assembly sol-gel method. The prepared samples with different promoters showed the high surface area ranging from 283.61 to 312.86m2/g. The characterization of prepared catalysts was determined using different BET, XRD, SEM, TPR and TPO analysis. The addition of Ce to Ni/MgAl2O4 dramatically improved the catalytic performance and the Ce-promoted catalysts exhibited the highest CH4 conversion among the promoted and unpromoted catalysts. Also Ce suppressed the carbon deposition because CeO2 enhanced the Ni dispersion and reactivity of carbon deposits. The findings of the study showed 3 wt. % Ce promoted catalysts exhibited the best performance in temperature and stability test, more than 50% CH4 with a lower amount of deposited carbon among other powders in dry reforming reaction. Also, no deactivation was observed for this catalyst at a period of 900 minutes of time on stream and at the special condition which despite high feed ratio CH4/CO2=2 and the high GHSV=24000 mL h-1 g-1cat.

RETRACTED: Rapid one-pot synthesis of Ag-decorated ZnO nanoflowers for photocatalytic degradation of tetracycline and product analysis by LC/APCI-MS and direct probe ESI-MS

A high potential nanostructure photocatalyst, Ag-decorated ZnO nanoflowers (Ag/ZnO NFs), was synthesized by a rapid one-pot surfactant-free microwave-assisted aqueous solution method. The morphology, structure, and optical property of Ag/ZnO were well-characterized. The method qualifies to be energy conserving and environment friendly. The size of the flower petals ranges from 200 to 250 nm and highly dispersed Ag nanoparticles (NPs) with dimensions ranging from 10 to 30 nm were anchored onto the surface of them. The as-prepared Ag/ZnO demonstrated enhanced photocatalytic performance in eliminating tetracycline (TC) aqueous solution under the illumination of visible light. The Ag/ZnO exhibited 100% degradation efficiency within 30 min. The effect of operating parameters such as pH, catalyst dose, and TC concentration was investigated. The reaction byproducts were identified by LC/APCI-MS (liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry) and ESI-MSn (electrospray ionization tandem mass spectrometry) analysis and a pathway was proposed as well. Kinetic studies indicated that the photodegradation process follows pseudo-first-order kinetics. The enhanced photocatalytic activity was due to the special architecture, the suppression of electron/hole (e–/h+) pair recombination, and the acceleration of surface charge transfer induced by the highly dispersive Ag NPs, which was further demonstrated by the cyclic voltammetry measurement.

A universal, facile and ultrafast monomer-tuned strategy to construct multi-dimensional hierarchical polymer structures and applications for lithium-ion batteries

Hierarchical polymer architectures have attracted considerable attention owing to their crucial roles in catalysis, drug delivery, biology, electronics and energy storage fields. Unfortunately, the current synthesis of polymer particles with hierarchical structures mainly relies on templates, hydrothermal devices, surfactants, and catalysts approaches that have the disadvantages of time-consuming procedures, complex manufacturing processes, high cost, the use of toxic agents (e.g. HF acid for templates removal) and potential risk of explosion (hydrothermal methods). Herein, for the first time, we have developed an ultrafast template-free, hydrothermal-free, surfactant-free, and catalyst-free precipitation polymerization method to synthesize a diversity of polymer particles with multi-dimensional (0D, 1D, 2D and 3D) hierarchical structures simply from polymerization of common dual-aldehyde and amino monomers at room temperature, and the fabrication process only took 10 min. After carbonizing one typical polymer particles (wool-ball-like structure) as an application example, we further tested the electrochemical performance of the as-obtained typical structures and the results show a reversible lithium-ion storage capacity of 226.5 mAh g−1 after 3200 cycles at the current density of 5 A g−1. Our technique provides a cost-effective, rapid, scalable, and green approach to prepare multi-dimensional hierarchical polymer structures and paves the way towards their application in a diversity of emerging fields.

Surfactant-free synthesis of carbon-supported silver (Ag/C) nanobars as an efficient electrocatalyst for alcohol tolerance and oxidation of sodium borohydride in alkaline medium

We have synthesized carbon-supported silver (Ag/C) nanobars by a simple surfactant-free hydrothermal method using glucose as the reducing reagent as well as the source of carbon in Ag/C nanobars. Physicochemical characterization of the materials was performed by X-ray Diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The XRD pattern confirmed the presence of a pure metallic silver phase. No carbon phase was detected, which indicates that the carbon exists mainly in the amorphous form. The electrocatalytic activity of Ag/C in different electrolyte solutions such as 0.5 M NaOH, 0.5 M NaOH + 1 M ethanol (EtOH), 0.5 M NaOH + 1 M ethylene glycol (EG), and 0.5 M NaOH + 0.01 M NaBH4 (sodium borohydride) was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) study. Alcohol tolerance of the catalysts was also established in the presence of ethanol and ethylene glycol. The forward-to-backward current ratio from cyclic voltammetry (CV) study of Ag/C-20 (20 h) in 0.5 M NaOH + 1 M ethanol solution at 100 mV s−1 scan rate is 4.13 times higher compared to that of Ag/C-5 (5 h). Hence, Ag/C-20 is a better candidate for the tolerance of ethanol. In the presence of ethylene glycol (1 M) in 0.5 M NaOH solution, it is obtained that the forward-to-backward current ratio at the same scan rate for Ag/C-20 is lower than that in the presence of ethanol. The durability of the catalyst was studied by chronoamperometry measurement. We studied the electrochemical kinetics of Ag/C catalysts for borohydride oxidation in an alkaline medium. The basic electrochemical results for borohydride oxidation show that Ag/C has very well strength and activity for direct borohydride oxidation in an alkaline medium. The reaction of borohydride oxidation with the contemporaneous BH4−. hydrolysis was noticed at the oxidized silver surface. Among all the synthesized Ag/C catalysts, Ag/C-20 exhibited the best electrocatalytic performance for borohydride oxidation in an alkaline medium. The activation energy and the number of exchange electrons at Ag/C-20 electrode surface for borohydride electro-oxidation were estimated as 57.2 kJ mol−1 and 2.27, respectively.

Facile synthesis of heterophase sponge-like Pd toward enhanced formic acid oxidation

The controllable preparation of noble metallic nanocrystals with a 3D architecture is of great interest for electrocatalysis applications due to their enhanced atomic utilization, facilitated mass transport, and other attractive properties. In this work, a facile, one-pot, and surfactant-free method of synthesizing heterophase sponge-like Pd (S-Pd) is developed. The prepared S-Pd has a four-fold higher peak current density and better durability than a commercial Pd/C catalyst for formic acid oxidation. It therefore has great potential as an anode catalyst for direct formic acid fuel cells.

New insights on the selective electroconversion of the cellulosic biomass-derived glucose at PtAu nanocatalysts in an anion exchange membrane fuel cell

Cellulosic biomass, which is basically a polymer of glucose, is the most abundant organic polymer on earth and there is significant interest in the development of advanced materials for its valorization through the waste-to-energy and water-to-chemical scenarios. Hence, a precise investigation of the monomer (glucose) electrooxidation in electrochemical reactors is a key starting point to tackle the whole cellulose and ultimately the entire biomass. To this end, we report herein new insights about the operation of a cogeneration direct alkaline glucose fuel cell (which includes an anion exchange membrane) that simultaneously produces electricity and mainly gluconate as the reaction product. The AuPt nanocatalysts of 3–5 nm particle size finely dispersed onto reduced graphene oxide (rGO) at a 20 wt% metal loading are obtained from an organic surfactant-free method, so-called the bromide anion exchange (BAE). Specifically, the electroanalytical investigation carried out with high-performance liquid ionic chromatography (HPLIC) and liquid chromatography coupled to mass spectrometry (LC-MS) demonstrate no carbon–carbon bond cleavage occurs, which represents an advance towards a CO2-free biomass valorization process. The comparison of the results commonly obtained in a three-electrode half-cell with those in an anion exchange membrane fuel cell shows that the trends in selectivity are the same. The fuel cell operation produces gluconate via a two-electron transfer process at 90% selectivity and 65% Faradaic efficiency. In addition to gluconate, glucuronate is also observed; both compounds are high value-added chemicals. This work contributes towards the engineering of novel electrocatalytic interfaces for the valorization of the surplus biomass into energy and chemicals.

Metal-Organic Framework Decorated Cuprous Oxide Nanowires for Long-lived Charges Applied in Selective Photocatalytic CO2 Reduction to CH4.

Improving the stability of cuprous oxide (Cu2 O) is imperative to its practical applications in artificial photosynthesis. In this work, Cu2 O nanowires are encapsulated by metal-organic frameworks (MOFs) of Cu3 (BTC)2 (BTC=1,3,5-benzene tricarboxylate) using a surfactant-free method. Such MOFs not only suppress the water vapor-induced corrosion of Cu2 O but also facilitate charge separation and CO2 uptake, thus resulting in a nanocomposite representing 1.9 times improved activity and stability for selective photocatalytic CO2 reduction into CH4 under mild reaction conditions. Furthermore, direct transfer of photogenerated electrons from the conduction band of Cu2 O to the LUMO level of non-excited Cu3 (BTC)2 has been evidenced by time-resolved photoluminescence. This work proposes an effective strategy for CO2 conversion by a synergy of charge separation and CO2 adsorption, leading to the enhanced photocatalytic reaction when MOFs are integrated with metal oxide photocatalyst.

Development of paclitaxel-loaded poly(lactic acid)/hydroxyapatite core-shell nanoparticles as a stimuli-responsive drug delivery system.

Biodegradable nanoparticles have been well studied as biocompatible delivery systems. Nanoparticles of less than 200 nm in size can facilitate the passive targeting of drugs to tumour tissues and their accumulation therein via the enhanced permeability and retention (EPR) effect. Recent studies have focused on stimuli-responsive drug delivery systems (DDS) for improving the effectiveness of chemotherapy; for example, pH-sensitive DDS depend on the weakly acidic and neutral extracellular pH of tumour and normal tissues, respectively. In our previous work, core–shell nanoparticles composed of the biodegradable polymer poly(lactic acid) (PLA) and the widely used inorganic biomaterial hydroxyapatite (HAp, which exhibits pH sensitivity) were prepared using a surfactant-free method. These PLA/HAp core–shell nanoparticles could load 750 wt% of a hydrophobic model drug. In this work, the properties of the PLA/HAp core–shell nanoparticles loaded with the anti-cancer drug paclitaxel (PTX) were thoroughly investigated in vitro. Because the PTX-containing nanoparticles were approximately 80 nm in size, they can be expected to facilitate efficient drug delivery via the EPR effect. The core–shell nanoparticles were cytotoxic towards cancer cells (4T1). This was due to the pH sensitivity of the HAp shell, which is stable in neutral conditions and dissolves in acidic conditions. The cytotoxic activity of the PTX-loaded nanoparticles was sustained for up to 48 h, which was suitable for tumour growth inhibition. These results suggest that the core–shell nanoparticles can be suitable drug carriers for various water-insoluble drugs.

A novel synthesis of hexagonal cylinder-like ZnO with an excellent performance by a surfactant-free microemulsion-hydrothermal method

A W/O surfactant-free microemulsion (SFME) template-hydrothermal method for the preparation of ZnO products was proposed. Using the SFME system containing hexane, propan-2-ol and water, hexagonal cylinder-like (twinning) ZnO microcrystals were synthesized. The XRD, SEM and TEM characterizations showed that the synthesized ZnO microcrystals have a hexagonal wurtzite structure. At hydrothermal temperatures of 120–140°C, hexagonal cylinder-like ZnO microcrystals were synthesized, whereas the hexagonal cylinder twinning ZnO microcrystals were obtained at 160°C. The growth mechanism of the ZnO microcrystals was also investigated.The EPR and XPS spectra of the synthesized ZnO products showed that there are oxygen vacancies on the ZnO surface. The photodegradation behavior of methylene blue (MB, 10ppm) with a UV-Hg lamp (250W) as the light source in ZnO aqueous suspension (0.3gL−1) was investigated. The ZnO product synthesized at 140℃ can significantly photocatalyze the degradation of lower concentration MB solutions. After 35min of irradiation, the photocatalytic decomposition rate reached 98.3%. It is hoped that this work could serve as an important stepping stone for establishing a novel hydrothermal method based on SFME system, therefore paving the way for other potential ideas on the application of SFME systems.

Micropore-Rich Yolk-Shell N-doped Carbon Spheres: An Ideal Electrode Material for High-Energy Capacitive Energy Storage.

Increasing the energy density of electrochemical double layer capacitors (EDLCs) can broaden their applications in energy storage but remains a formidable challenge. Herein, micropore-rich yolk-shell structured N-doped carbon spheres (YSNCSs) were constructed by a one-pot surfactant-free self-assembly method in aqueous solution. The resultant YSNCSs after activation possessed an ultrahigh surface area of 2536 m2 g-1 , among which 80 % was contributed from micropores. When applied in EDLCs, the activated YSNCSs demonstrated an unprecedentedly high capacitance (270 F g-1 at 1 A g-1 ) in 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4 ]) ionic liquid, affording an ultrahigh energy density (133 Wh kg-1 at 943 W kg-1 ). The present contribution provides insight into engineering porous carbons for capacitive energy storage.

Thermocatalytic CO2 Conversion over a Nickel-Loaded Ceria Nanostructured Catalyst: A NAP-XPS Study.

Despite the increasing economic incentives and environmental advantages associated to their substitution, carbon-rich fossil fuels are expected to remain as the dominant worldwide source of energy through at least the next two decades and perhaps later. Therefore, both the control and reduction of CO2 emissions have become environmental issues of major concern and big challenges for the international scientific community. Among the proposed strategies to achieve these goals, conversion of CO2 by its reduction into high added value products, such as methane or syngas, has been widely agreed to be the most attractive from the environmental and economic points of view. In the present work, thermocatalytic reduction of CO2 with H2 was studied over a nanostructured ceria-supported nickel catalyst. Ceria nanocubes were employed as support, while the nickel phase was supported by means a surfactant-free controlled chemical precipitation method. The resulting nanocatalyst was characterized in terms of its physicochemical properties, with special attention paid to both surface basicity and reducibility. The nanocatalyst was studied during CO2 reduction by means of Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). Two different catalytic behaviors were observed depending on the reaction temperature. At low temperature, with both Ce and Ni in an oxidized state, CH4 formation was observed, whereas at high temperature above 500 °C, the reverse water gas shift reaction became dominant, with CO and H2O being the main products. NAP-XPS was revealed as a powerful tool to study the behavior of this nanostructured catalyst under reaction conditions.

Commercial Spirits for Surfactant-Free Syntheses of Electro-Active Platinum Nanoparticles

The Co4CatTM process is a simple, surfactant-free method to produce colloidal dispersions of precious metal nanoparticles in alkaline mono-alcohols. The synthesis is performed in low-boiling-point solvents and is relevant for industrial production. The robustness of the process is demonstrated by using three different commercial spirits as solvents to obtain Pt nanoparticles. The results demonstrate that careful control of the solvent purity is not needed to achieve the synthesis of stable 2 nm platinum nanoparticle colloids readily active electrocatalysts for energy conversion reactions like the methanol oxidation.

Type-II Heterojunctions in SnO2-Coated TiO2 Core-Shell Nanoparticles

Titanium dioxide (TiO2) and tin oxide (SnO2) are two popular wide band-gap semiconductors for photocatalytic and electronic applications such as solar cells, optoelectronic devices, and lithium-ion batteries. Nanosized TiO2 structures have strong absorption in the UV region while SnO2 is a powerful transparent conducting oxide. Composites of TiO2 and SnO2 are especially attractive since they form a type-II heterojunction extending the lifetime of charge carriers and enhancing photoconversion efficiency. In this study, the synthesis of TiO2 nanoparticles as well as their uniform and controlled coating with SnO2 shells are described, providing the first utilization of sodium stannate to grow SnO2 shells on a metal-oxide core. The step-growth method utilized here shows the ability to vary the shell thickness between 5-40 nm while maintaining uniformity of the shell. As such, the complete synthesis route involves facile and reproducible surfactant-free solution-based methods at moderate temperatures. The nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Overall, this paper represents reliable nanoscale fabrication techniques offering key advancements in photovoltaic and optoelectronic applications. Keywords: TiO2, SnO2, Heterojunction, Core-shell, Nanoparticles, Wide Band-gap Semiconductor