Inorganic Shell Research Articles

Preparation and characterization of novel microencapsulated phase change materials with SiO2/FeOOH as the shell for heat energy storage and photocatalysis

A novel microencapsulated phase change material (paraffin@SiO2/FeOOH) was prepared by an interfacial polycondensation method. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results revealed that the microcapsules were regular spherical with a diameter of 2 ∼ 5 µm. The DSC analysis results showed that the melting point and latent heat of the paraffin@SiO2/FeOOH microcapsules were 26.10 °C and 104.44 J/g, encapsulation rate of the paraffin@SiO2/FeOOH microcapsules was 49.68%. As the TGA and photo-thermal performance measurements showed, inorganic shell material not only effectively improves thermal stability of phase change microcapsules, but also exhibited a certainly photo-thermal conversion property. Additionally, the experimental results of photocatalytic degradation of MB (Methylene blue) showed that paraffin@SiO2/FeOOH microcapsules have high photocatalytic activity against organic dyes under natural light. The developed materials can be applied to the fields of residential building temperature adjustment materials and the degradation of organic pollutants.

The preparation of mono- and multicomponent nanoparticle aggregates with layer-by-layer structure using emulsion templating method in microfluidics

We report on the preparation of multicomponent hollow aggregates by an emulsion templating method adapted to microfluidic format. The method exploits partial miscibility of aqueous colloidal solutions as discrete phase and n-butanol as continuous phase. The aggregates consisted of an inner inorganic shell composed of iron oxide (IO) and gold nanoparticles (Au NPs) covered with polycaprolactone (PCL) NPs. The aggregates of smaller sizes were prepared compared to immiscible phases due to the diffusion-controlled shrinkage of aqueous droplets. The aggregate surface properties were controlled by using different mobilities and affinities of IO, Au, and PCL NPs to the water:n-butanol interface. The biocompatible surface layer enclosing an inorganic shell with a core space for possible cargo loading endowed these constructs with properties appreciated in medicinal applications. A computational fluid dynamics model enabled the prediction of the droplet size and formation frequency together with flow field properties at the point of droplet detachment.

Dual Responsive Hybrid Nanoparticle for Tumor Chemotherapy Combined with Photothermal Therapy

With the deepening of tumor targeting research, the application of intelligent responsive drug carriers in the field of controlled drug release has become more and more extensive, and multiple responsive nano drug carriers have attracted greater attention. In this paper, nanoparticles with gold nanorods (GNR) as the core, mesoporous silica (mSiO2) doped with hydroxyapatite (HAP) as the inorganic hybrid shell and physically loaded with doxorubicin hydrochloride (DOX·HCl) are prepared (DOX/GNR/mSiO2/HAP, DNPs). DNPs nanoparticles have a typical core-shell structure. The gold nanorods as the core have extremely high light-to-heat conversion efficiency. Under the irradiation of near-infrared light, light can be converted into heat. The inorganic hybrid shell is a drug reservoir. The excellent photothermal response of gold nanorods combined with the excellent pH response of hydroxyapatite can obtain slow and sustained release of chemotherapeutic drugs. In vivo and in vitro anti-tumor cell activity study show that the DNPs in the laser showed stronger cytotoxicity than the other groups. Compared to chemotherapy and phototherapy alone, DNPs selectively accumulate in the tumor through the enhanced penetration and retention (EPR) effects. and have the unified function of hyperthermia and chemotherapy, and have significant inhibitory effect on tumor growth. Therefore, this study provides a new idea for the study of the combination of multiple therapeutic methods in the treatment of cancer.

Characterization and Cytotoxicity Comparison of Silver- and Silica-Based Nanostructures.

Core-shell structures are the most common type of composite material nanostructures due to their multifunctional properties. Silver nanoparticles show broad antimicrobial activity, but the safety of their utilization still remains an issue to tackle. In many applications, the silver core is coated with inorganic shell to reduce the metal toxicity. This article presents the synthesis of various materials based on silver and silica nanoparticles, including SiO2@Ag, Ag@SiO2, and sandwich nanostructures—Ag@SiO2@Ag—and the morphology of these nanomaterials based on transmission electron microscopy (TEM), UV-Vis spectroscopy, and FT-IR spectroscopy. Moreover, we conducted the angle measurements due to the strong relationship between the level of surface wettability and cell adhesion efficiency. The main aim of the study was to determine the cytotoxicity of the obtained materials against two types of human skin cells—keratinocytes (HaCaT) and fibroblasts (HDF). We found that among all the obtained structures, SiO2@Ag and Ag@SiO2 showed the lowest cell toxicity and very high half-maximal inhibitory concentration. Moreover, the measurements of the contact angle showed that Ag@SiO2 nanostructures were different from other materials due to their superhydrophilic nature. The novel approach presented here shows the promise of implementing core-shell type nanomaterials in skin-applied cosmetic or medical products.

Facile Control of Structured ZnO Polymeric Nanoparticles through Miniemulsion Polymerization: Kinetic and UV Shielding Effects.

Zinc oxide polymeric nanoparticles (ZPPs) of poly (styrene-co-acrylic acid) P(St/AA), containing oleic acid modified zinc oxide nanoparticles (OA-ZnO NPs), were synthesized via miniemulsion polymerization. By simply adjusting the quantity of reactants, i.e., sodium dodecyl sulfate (SDS) surfactant, potassium persulfate (KPS) initiator, and divinyl benzene (DVB) crosslinking agent, the location of ZnO NPs were altered from the inner (core) to the outer (shell), leading to core-shell and Pickering-like morphologies, respectively. The Pickering-like ZPPs were obtained when using SDS at below or equal to the critical micelle concentration (CMC). At above the CMC, the complete encapsulation of OA-ZnO NPs within the ZPPs depicted a kinetically controlled morphology. The transition to Pickering-like ZPPs also occurred when reducing the KPS from 2 to 0.5–1%. Whereas the DVB accelerated the polymerization rate and viscosity in the growing monomer-swollen nanodroplets and, hence, contributed to kinetic parameters on particle morphology, i.e., an increase in the DVB content increased the rate of polymerization. A hollow structure was obtained by replacing styrene with the more hydrophilic monomer, i.e., methyl methacrylate. All ZPPs-incorporated poly (vinyl alcohol) (PVA) films greatly improved shielding performance over the UV region and were relatively transparent on a white paper background. Due to the large number of ZnO NPs in the central region and, hence, the ease of electron transfer, composite films containing core-shell ZPPs possessed the highest UV blocking ability. ZnO NPs in the outer part of the hollow and Pickering-like ZPPs, on the other hand, facilitated the multiple light scattering according to the difference of refractive indices between the inorganic shell and organic/air core. These results confirm the advantage of structured ZPPs and their potential use as transparent UV shielding fillers.

Formation of the Inorganic and Organic Shells on the Surface of CdSe Quantum Dots.

Embedding quantum dots (QDs) into an organic matrix of controllable order requires the identification of their structural characteristics. This analysis is necessary for the creation of anisotropic composites that are sensitive to external stimuli. We have studied the QD structures formed during the single-step synthesis of CdSe/ZnS QDs and their transformations after the initial ligand's substitution for another ligand. This single-step process leads to the formation of the core/shell structure. We detect the presence of two oleic acid residues ionically connected to Zn and Cd. At the same time, the amount of Cd oleate at the surface is very small. We observe the ligand exchange process at the surface of the core/shell QDs. The oleic acid residues are substituted by terphenyl-containing (TERPh-COOH) aromatic acid residues. The reaction between CdSe/ZnS carrying TOP and oleic acid residues ionically bound with QDs and terphenyl-containing acid leads to the coexistence of multiple ligands on the QD surface at a ratio of 11:6:33 for TOP/OA/TERPh-COOH.

Well-defined organic–inorganic core–shell structure IPN-P(AA-co-AM) polymer spheres by modified suspension polymerization

Well-defined organic–inorganic core–shell structure IPN-P(AA-co-AM) polymer spheres by modified suspension polymerization

CdS Nanoplates Modification as a Platform for Synthesis of Blue-Emitting Nanoparticles.

In this paper, the study of surface modification of two-dimensional (2D), non-luminescent CdS nanoplates (NPLs) by thiol-containing ligands is presented. We show that a process of twophase transfers with appropriate ligand exchange transforms non-luminescent NPLs into spherical CdS nanoparticles (NPs) exhibiting a blue photoluminescence with exceptionally high quantum yield ~90%. In the process, transfer from inorganic solvent to water is performed, with appropriately selected ligand molecules and pH values (forward phase transfer), which produces NPs with modified size and shape. Then, in reverse phase transfer, NPs are transferred back to toluene due to surface modification by combined Cd (OL)2 and Cd (Ac)2. As a result, spherical NPs are formed (average diameter between 4 and 6 nm) with PL QY as high as 90%. This is unique for core only CdS NPs without inorganic shell.

Silica-encapsulated red phosphorus for flame retardant treatment on textile

Red phosphorus (RP) particles are commercially available as a flame-retardant additive for polymers. Conventionally, RP is encapsulated with a protective organic coating. In the present work, we propose an alternative approach for the encapsulation of RP with an inorganic SiO2 shell (SiO2@RP), to be employed in textiles. The silica shell was obtained by two steps sol-gel of tetraethyl orthosilicate (TEOS) precursor in RP aqueous dispersion. A homogenous silica shell was consistently achieved. The chemical structure and morphology of the as-obtained powder were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the silica coating on the thermal stability of RP was investigated through thermogravimetric coupled-differential thermal analysis (DT-TGA) that revealed improved thermo-oxidative stability. The application of the prepared coated and uncoated RP as flame retardant additives for fabric back-coating is then investigated. Only the fabrics treated with SiO2@RP successfully self-extinguished the flame during flammability test, based on BS-5852 normative, achieving the no-ignition classification required for a practical application. The proposed fully inorganic encapsulation strategy opens up to new and efficient flame retardant solutions based on RP that can potentially be exploited in several application fields.

Triggerable Super Absorbent Polymers for Coating Debonding Applications.

This study aims to examine how core–shell super absorbent polymers (SAPs) can be effective in relation to recycling processes by using them as triggerable materials in coating binders. Super absorbent polymers are partially cross-linked, three-dimensional polymer networks that can absorb and retain water. Coatings based on an acrylic binder, including SAPs, were applied onto plastic substrates of acrylonitrile–butadiene–styrene/polycarbonate. The incorporation of 1 wt.% and 5 wt.% SAPs into the coatings resulted in the debonding of the coatings from the substrates under a steam treatment. The trigger mechanism for the core–shell hydrophilic SAPs relies on the different abilities of the core and shell materials to be swollen. Therefore, under the influence of steam, SAPs can enhance their shape due to water absorption and the breaking of the inorganic shell. This results in the reduction of the attachment between the primer layer and both the top coating and the substrate, thus enabling the detachment of the top coating from the corresponding substrate. The obtained results from this study can be considered as potential formulations for plastic recycling applications in industries.

Microencapsulation of Thermochromic Material by Silicon Oxide Nanoparticles

This study is mainly focused on the fabrication of SiO2 as an inorganic shell material encapsulated an organic thermochromic (TC) core material comprises of either the (i) three-component as-synthesized blue dyes [BDTCM@SiO2] or (ii) off-the-shelf (commercial) black dyes [CDTCM@SiO2]. Both the SiO2 encapsulated thermochromic systems have successfully demonstrated the color transition at around 31 °C. For the three-component thermochromic microcapsules, we have used the crystal violet lactone (CVL) as a leuco dye, bisphenol-A (BPA) as a color developer, and 1-tetradecanol (TD) as a solvent. Different ratios of the thermochromic dye and the metal oxide were prepared to examine the effect of the core@shell ratio on the microstructural and thermal properties of the encapsulated microcapsules. The mean particles sizes of the BDTCM@SiO2 are below 100 nm, whereas, the CDTCM@SiO2 samples exhibited the mean particle sizes varied in a range of 100-1000 nm. The endothermic phase transition due to melting and in general, the thermal stabilities of these SiO2 encapsulated TCMs have been explored for the purpose of deploying these systems for thermal energy savings or storage applications.

Dual-Protected Metal Halide Perovskite Nanosheets with an Enhanced Set of Stabilities.

Approaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at a single-nanocrystal (NC) level are comparatively few and limited in scope. Reported here is a robust amphiphilic-diblock-copolymer-enabled strategy for crafting highly-stable anisotropic CsPbBr3 nanosheets (NSs) by in situ formation of a uniform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dual-protected NSs display an array of remarkable stabilities (i.e., thermal, photostability, moisture, polar solvent, aliphatic amine, etc.) and find application in white-light-emitting diodes. In principle, by anchoring other multidentate amphiphilic polymer ligands on the surface of PNCs, followed by templated-growth of shell materials of interest, a rich variety of dual-shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics, optoelectronics, and sensory devices.

Dual‐Protected Metal Halide Perovskite Nanosheets with an Enhanced Set of Stabilities

AbstractApproaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at a single‐nanocrystal (NC) level are comparatively few and limited in scope. Reported here is a robust amphiphilic‐diblock‐copolymer‐enabled strategy for crafting highly‐stable anisotropic CsPbBr3 nanosheets (NSs) by in situ formation of a uniform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dual‐protected NSs display an array of remarkable stabilities (i.e., thermal, photostability, moisture, polar solvent, aliphatic amine, etc.) and find application in white‐light‐emitting diodes. In principle, by anchoring other multidentate amphiphilic polymer ligands on the surface of PNCs, followed by templated‐growth of shell materials of interest, a rich variety of dual‐shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics, optoelectronics, and sensory devices.

The Effect of Superabsorbent Polymers on the Microstructure and Self-Healing Properties of Cementitious-Based Composite Materials

Cementitious structures have prevailed worldwide and are expected to exhibit further growth in the future. Nevertheless, cement cracking is an issue that needs to be addressed in order to enhance structure durability and sustainability especially when exposed to aggressive environments. The purpose of this work was to examine the impact of the Superabsorbent Polymers (SAPs) incorporation into cementitious composite materials (mortars) with respect to their structure (hybrid structure consisting of organic core—inorganic shell) and evaluate the microstructure and self-healing properties of the obtained mortars. The applied SAPs were tailored to maintain their functionality in the cementitious environment. Control and mortar/SAPs specimens with two different SAPs concentrations (1 and 2% bwoc) were molded and their mechanical properties were determined according to EN 196-1, while their microstructure and self-healing behavior were evaluated via microCT. Compressive strength, a key property for mortars, which often degrades with SAPs incorporation, in this work, practically remained intact for all specimens. This is coherent with the porosity reduction and the narrower range of pore size distribution for the mortar/SAPs specimens as determined via microCT. Moreover, the self-healing behavior of mortar-SAPs specimens was enhanced up to 60% compared to control specimens. Conclusively, the overall SAPs functionality in cementitious-based materials was optimized.

Preparation and Performance of Microencapsulated Phase Change Material with Paraffin Core and SiO2 Shell for High Latent Heat and Low Heat Loss by Sol–Gel Method

Microencapsulated phase change materials (MicroPCM) were prepared via sol–gel method using paraffin as heat storage core and silica as inorganic shell. The morphology feature, chemical structure, thermal properties and thermal stability of MicroPCM were characterized by the field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR), the differential scanning calorimeter (DSC), simultaneous thermal analyzer (STA) and the thermal conductivity meter. The results indicated that MicroPCM were spherical in shape with the shell thickness in the range from 236[Formula: see text]nm to 303[Formula: see text]nm. The stirring speed and TEOS dosage were key factor on the latent heat and supercool effect of MicroPCM. The maximum latent heat of MicroPCM was 240.2[Formula: see text][Formula: see text] with the heat loss of only 0.2[Formula: see text][Formula: see text] in phase transformation when it was prepared at the stirring speed of 400[Formula: see text]r/min and TEOS dosage of 20[Formula: see text]ml. MicroPCM was a promising material for thermal energy storage (TES).

Embedding Quantum Dots with High Quantum Yield in Inorganic Matrix By Sol-Gel Method

Colloidal quantum dots (QDs) are semiconductor nanoparticles, size of which is 10 nm or less. Some of QDs are known to show a wide spectral range of absorption and emit a highly monochromatic photoluminescence (PL) from the band-edge transition as one of their properties of direct semiconductors. However, cadmium selenide (CdSe) QDs, one of the most investigated QDs exhibit PL with relatively low quantum yield (QY) of ~10% due to intrinsic surface defects resulting in the quenching of excitons. Typically, a practical PL QY of ~80% is achieved by coating the core-only CdSe QDs with CdS and/or ZnS shells to passivate their surface. Thus, the QDs have gained the position of next-generation fluorescent materials and applied to display, electroluminescence (EL) device, and bioimaging. In addition to the shells, QDs have an awkward complexity arising from surface-adsorbed ligands that are organic molecules coordinating to outermost layer of QDs, compared to inorganic fluorescent materials. Along with the inorganic shells, recent studies have revealed that organic ligands also provide insulating characteristics to the QDs and support to prevent excitons leaking out from the QDs. In other words, their role is not only to keep QDs dispersed but also to play an essential role for the emission even if the QDs have the core/shell structure. On the other hand, their own weakness due to their organic nature and coordination bond with QDs sometimes impair long term stability of the materials due to degradation and/or desorption, leading to the formation of carrier trap states. In this study, we developed a way to keep band-edge emission without using organic ligands when embedding QDs in inorganic matrix prepared by sol-gel method. Two types of QDs, CdSe/CdS/ZnS core/multishell QDs and AgInS2/GaSx core/shell QDs are embedded in ZnS and GaSx matrix, respectively, by growing the matrices from the surface of the QDs. To prepare CdSe/CdS/ZnS QDs embedded in ZnS matrix, colloidal CdSe/CdS/ZnS QDs were firstly synthesized following previous report,1 and they were transferred to 1-propanol solution by ligand exchange to 4-tert-butylpyridine. Then, they were mixed with ZnS precursor solution containing zinc acetate, thioacetamide and 4-amino-1-buthanol2, were reacted for several hours at room temperature. Pale orange powders showing intense photoluminescence were successfully obtained. To prepare AgInS2/GaSx QDs embedded in GaSx matrix, AgInS2/GaSx QDs were synthesized following previous report3 and were embedded in GaSx by the similar sol-gel method by using a gallium source instead of the zinc source. Fig.1a and 1b show photographs of CdSe/CdS/ZnS QDs embedded in ZnS matrix under room light and UV light, the latter of which gave a PL QY over 60%. This value was even higher than that obtained in colloidal state, as shown in Fig.2. These results indicated that ZnS matrix could confine the excitons inside the QDs more strongly than organic ligands (4-tert-butylpyridine) and promote radiative recombination in the QDs. In terms of stability over time, PL QY of embedded QDs that were stocked in air at room temperature were maintained their luminescence property over 9 months. In contrast, the original QDs in colloidal state decreased their PL QY due to the deterioration of the surface condition. AgInS2/GaSx QDs embedded in GaSx matrix also showed PL QY of over 50% and were observed the improvement of durability over time as same as CdSe/CdS/ZnS QDs. Figure 1

Fabrication and Evaluation of Electroluminescence Devices Using Quantum Dots As Light Emitting Materials

Colloidal quantum dots (QDs) have been attracting intense attention as promising candidates for new generation photoluminescent materials due to their fascinating optical properties, such as wide-band absorption, narrow-band emission, and high photoluminescence efficiency. These unique properties originate from semiconducting nature of the QD cores. The core is usually protected by an inorganic shell made of wider-gap semiconductors, resulting in photoluminescence quantum yield (PLQY) as high as 80%. CdSe-CdS and CdSe-ZnS core-shell QDs are such typical examples. Electroluminescence (EL) devices containing QDs in their emitting materials, which are known as QLEDs, have been demonstrated as a new type of display device providing better monochromaticity than conventional organic LED (OLEDs). However, the electroluminescence efficiencies of QLEDs have been inferior to that of OLEDs due probably to mismatch of the structure that has been developed based on OLEDs. Typically, the deep energy level of a valence band-edge (VB-edge) of the QDs hinders hole injection into QDs from HOMO of organic hole transport materials. Although developing new type of hole transport material is essential, one of the “indirect” strategies to solve this problem would be use of ZnO nanoparticles as an electron transport layer (ETL), which make use of deeper energy level of a VB-edge of ZnO nanoparticles. The resulting structure allows to accumulate holes in QD layer and facilitates hole injection into the QDs. However, the device structure of QLEDs still needs to be improved for more enhancing electroluminescence efficiencies. This study was carried out to design QLEDs structure which allows efficient charge injection into QDs by changing materials and thickness of the hole injection layer (HIL), and electron transport layer (ETL). The device performance was evaluated by voltage– current and voltage–luminance plots, and external quantum efficiency (EQE). CdSe-CdS-ZnS core-shell-shell nanoparticles used here were synthesized by the previously reported methods. Figure 1(a) shows the structure of the devices which consisted of layers of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): polystyrene (PEDOT:PSS, 6 nm)/poly(N-vinylcarbazole) (PVK, 37 nm)/CdSe-CdS-ZnS core-shell-shell QDs (14 nm)/ZnO nanoparticles (x nm)/LiF (1 nm)/Al (100 nm), where the thickness of the ZnO layer was varied between 10 nm and 70 nm. Except for LiF and Al layers, which was deposited using the vacuum thermal evaporation, each layer was sequentially formed on ITO-patterned glasses by spin-coating. Figure 1(b) shows the normalized EL spectrum of the QLEDs having an emission peak at 628 nm with a narrow full-width at half-maximum of 35 nm. The inset shows the picture of device (3×3 mm) demonstrating the formation of uniform emission. Figure 1(c) shows the voltage–luminance plots for CdSe-based QLEDs. The device of x = 12 nm only attained a maximum luminance of 298 cd/m2 and a maximum EQE of 0.063% although enough current was flowing (~100 mA). This result indicates the occurrence of charge imbalance, probably because the holes were leaked out to reach the cathode (Al) due to the insufficient ZnO nanoparticle layer thickness. Then, the thickness of ZnO nanoparticle layer was gradually increased to x=31, 48, 68 nm, raising steady the values of maximum luminance and EQE. These results suggested that the thickness of each layer might have effects on hole-electron balance. The hole-only and electron-only devices were fabricated using the same CdSe-CdS-ZnS core-shell-shell QDs and voltage–current curves were measured. The electron-only device passed larger current than the hole-only device, indicating the lower resistance for electron injection and transport than hole injection and transport. These facts corresponded with the previous results that increment of ZnO layer improved the device performance. Finally, the device was modified based on that with x = 68 nm. The use of PEDOT:PSS (HIL) having lower resistance were fabricated to further improve the charge balance. As a result, the device achieved a maximum luminance of 6500 cd/m2 and a maximum EQE of 1.3%. Figure 1

Multimodal image-guided folic acid targeted Ag-based quantum dots for the combination of selective methotrexate delivery and photothermal therapy

Multifunctional quantum dots (QDs) with photothermal therapy (PTT) potential loaded with an anticancer drug and labelled with a targeting agent can be highly effective nano-agents for tumour specific, image-guided PTT/chemo combination therapy of cancer. Ag-chalcogenides are promising QDs with good biocompatibility. Ag2S QDs are popular theranostic agents for imaging in near-infrared with PTT potential. However, theranostic applications of AgInS2 QDs emitting in the visible region and its PTT potential need to be explored. Here, we first present a simple synthesis of small, glutathione (GSH) coated AgInS2 QDs with peak emission at 634 nm, 21% quantum yield, and excellent long-term stability without an inorganic shell. Ag2S-GSH QDs emitting in the near-infrared region (peak emission = 822 nm) were also produced. Both QDs were tagged with folic acid (FA) and conjugated with methotrexate (MTX). About 3-fold higher internalization of FA-tagged QDs by folate-receptor (FR) overexpressing HeLa cells than HT29 and A549 cells was observed. Delivery of MTX by QD-FA-MTX reduced the IC50 of the drug from 10 μg/mL to 2.5–5 μg/mL. MTX release was triggered at acidic pH, which was further enhanced with local temperature increase created by laser irradiation. Irradiation of AgInS2-GSH QDs at 640 nm (300 mW) for 10 min, caused about 10 °C temperature increase but did not cause any thermal ablation of cells. On the other hand, Ag2S-GSH-FA based PTT effectively and selectively killed HeLa cells with 10 min 808 nm laser irradiation via mostly necrosis with an IC50 of 5 μg Ag/mL. Under the same conditions, IC50 of MTX was reduced to 0.21 μg/mL if Ag2S-GSH-FA.

Synthesis, characterization and thermal analysis of microencapsulated alumina–myristic acid phase change material for thermal energy storage

Alumina (Al2O3) is an inorganic shell material with desirable properties such as high thermal conductivity, chemical stability, resistance to corrosion and high thermal diffusivity. In this work, microcapsules with myristic acid (MA) core and alumina shell were generated by sol–gel technique. Aluminum isopropoxide (AIP) has been used as a shell forming reagent. The analytical and thermal characterizations of microencapsulated MA@Al2O3 are reported. Three weight ratios of MA/ (AIP), (1:1), (1:0.75) and (1:0.5) were made by varying the compositions of MA and AIP. SEM results revealed that the MA@Al2O3 microcapsules have a spherical shape with a grain size of 2–5 μm. The maximum weight loss of microcapsules is comparatively higher than pristine material. Thermal stability of the MA improved after encapsulation. The DSC results revealed an encapsulation ratio 88% and encapsulation efficiency of 92% for the (1:1) ratios with a latent heat of 150 J/g during solidification and 147 J/g during crystallization.

Highly Scattering Hierarchical Porous Polymer Microspheres with a High-Refractive Index Inorganic Surface for a Soft-Focus Effect.

Functional light scattering materials have received considerable attention in various fields including cosmetics and optics. However, a conventional approach based on optically active inorganic materials requires considerable synthetic effort and complicated dispersion processes for special refractive materials. Here, we report a simple and effective fabrication strategy for highly scattering hierarchical porous polymer microspheres with a high-refractive index inorganic surface that mitigates the disadvantages of inorganic materials, producing organic-inorganic hybrid particles with an excellent soft-focus effect. Hierarchical organic-inorganic hybrid particles were synthesized using the simple physical mixing of porous poly (methyl methacrylate) (PMMA) microparticles with different pore sizes and regularities as the organic core and titanium dioxide (TiO2) nanoparticles with different particle sizes as the inorganic shell. The polar noncovalent interactions between polar PMMA microspheres and the polar surface of TiO2 nanoparticles could induce the hierarchical core-shell structure of hybrid particles. The synthesized hybrid particles had increased diffuse reflectance properties of up to 160% compared with single inorganic particles. In addition, the light scattering efficiency and soft-focus effect could be increased further, depending on the size of the TiO2 nanoparticles and the pore characteristics of the PMMA microspheres. The proposed study can provide a facile and versatile way to improve the light scattering performance for potential cosmetics.