Composite Microparticles Research Articles

Experimental investigation of pool boiling on Ti-Cu composite coated surfaces prepared using Electric Discharge Coating

Boiling heat transfer has become a very potent two-phase heat transfer mechanism for cooling high heat-producing devices such as microelectronic devices, fusion reactors or turbine blades. Increasing research has shown that micro/nano-structures on surfaces increase the number of nucleation sites for bubble formation, which ultimately results in a major improvement in boiling performance. This led to studies on developing various coated surfaces in order to generate micro/nano-structures on surfaces. In the current study, microstructured boiling surfaces were prepared using the Electric Discharge Coating (EDC) process. Titanium-copper (Ti-Cu) composite microparticles were coated on copper surface under reverse polarity in the Electric Discharge Machine. Four surfaces were prepared by using current settings of 3 A, 4 A, 5 A and 6 A. It was followed by characterisation of the surfaces which included, wettability analysis, porosity, pore size estimation, mean roughness measurement and elemental analysis, in order to better understand the boiling results on the surfaces. The surfaces formed were hydrophilic in nature, with contact angles varying from 47° to 65°. Pool boiling were performed with the developed surfaces and critical heat flux (CHF) and nucleate boiling heat transfer coefficient (NBHTC) improvement of 37.17 % and 172 % respectively were observed with the best performing surface compared to the bare surface. The best performing surface was also compared with relevant published literature to determine its standing against the present state of the art.

Preparation and Characterization of Cellulose/Silk Fibroin Composite Microparticles for Drug-Controlled Release Applications.

Microparticles derived from biomaterials are becoming increasingly popular for application in drug delivery systems. In this study, the water-in-oil (W/O) emulsification-diffusion method was used to create cellulose (C), silk fibroin (SF), and C/SF composite microparticles. We then observed the morphology of all obtained microparticles using scanning electron microscopy (SEM), evaluated their functional groups using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and conducted thermogravimetric analysis using a thermogravimetric analyzer (TGA). SEM micrographs indicated that the native SF microparticles have the highest spherical shape with smooth surfaces. With blue dextran, the C microparticle was smaller than the native microparticle, while the drug-loaded SF microparticles were larger than the native microparticle. The morphological surfaces of the C/SF composite microparticles were varied in shape and surface depending on the C/SF ratio used. The spherical shape of the C/SF composite microparticle increased as the SF content increased. Furthermore, the size of the drug-loaded C/SF composite microparticles increased when the SF content gradually increased. The significant functional groups in the C and SF structures were identified based on the ATR-FTIR data, and a suggestion was made regarding the interaction between the functional groups of each polymer. When compared to both native polymers, the C/SF composite microparticles exhibit improved thermal stability. XRD patterns indicated that all prepared particles have crystalline structures and are directly affected by the released profile. The C/SF composite microparticle at a 1:3 ratio had the lowest drug release content, whereas the hydrophilicity of the C microparticle affected the highest drug release content. As a result, one crucial factor affecting the medication released from the microparticle is its structure stability. According to the obtained results, C, SF, and C/SF composite microparticles show promise as delivery systems for drugs with controlled release.

Investigating Microstructural and Mechanical Behavior of DLP-Printed Nickel Microparticle Composites

The study investigates the fabrication and analysis of nickel microparticle-reinforced composites fabricated using the digital light processing (DLP) technique. A slurry is prepared by incorporating Ni-micro particles into a resin vat; it is thoroughly mixed to achieve homogeneity. Turbidity fluctuations are observed, initially peaking at 50% within the first two minutes of mixing and then stabilizing at 30% after 15–60 min. FTIR spectroscopy with varying Ni wt.% is performed to study the alterations in the composite material’s molecular structure and bonding environment. Spectrophotometric analysis revealed distinctive transmittance signatures at specific wavelengths, particularly within the visible light spectrum, with a notable peak at 532 nm. The effects of printing orientation in the X, Y, and Z axes were also studied. Mechanical properties were computed using tensile strength, surface roughness, and hardness. The results indicate substantial enhancements in the tensile properties, with notable increases of 75.5% in the ultimate tensile strength and 160% in the maximum strain. Minimal alterations in surface roughness and hardness suggest favorable printability. Microscopic examination revealed characteristic fracture patterns in the particulate composite at different values for the wt.% of nickel. The findings demonstrate the potential of DLP-fabricated Ni-reinforced composites for applications demanding enhanced mechanical performance while maintaining favorable printability, paving the way for further exploration in this domain.

Deoxycholate-Based Composite Microparticles for Localized Adipocytolysis

Deoxycholate-Based Composite Microparticles for Localized Adipocytolysis

Raspberry-liked Pickering emulsions based inulin microparticles for enhanced antibacterial performance of essential oils

Pickering emulsions seem to be an effective strategy for encapsulation and stabilization of essential oils. In this work, a novel raspberry-liked Pickering emulsion (RPE) loading Mosla chinensis ‘Jiangxiangru’ essential oil (MJO) was successfully engineered by using ethyl lauroyl arginate (ELA) decorated nanosilica (ELA-NS) as particles emulsifier. And the ELA-NS-stabilized MJO Pickering emulsion (MJO-RPE) was further prepared into inulin-based microparticles (MJO-RPE-IMP) by spray-drying, using inulin as matrix formers. The concentration of ELA-NS could affect the formation and stabilization of MJO-RPE, and the colloidal behavior of ELA-NS could be modulated at the interfaces with concentration of ELA, thus providing unique role on stabilization of MJO-RPE. The results indicated that the MJO-RPE stabilized ELA-NS with 2 % NS modified by 0.1 % ELA had long-term stability. MJO-RPE exhibited a raspberry-liked morphology on the surface, attributed to ELA-NS covered in the droplet surface. The inulin-based matrix formers could effectively prevent MJO-RPE from agglomeration or destruction during spray-drying, and 100 % concentration of inulin based microparticles formed large composite particles with high loading capacity (98.54 ± 1.11 %) and exhibited superior thermal stability and redispersibility of MJO-RPE. The MJO-RPE exhibited strong antibacterial efficacy against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa), owing to the adhesion to bacterial membrane dependent on the raspberry-liked surface of MJO-RPE, whose minimum inhibitory concentration (MIC) of the above three bacteria were (0.3, 0.45, and 1.2 μL/mL), respectively, lower than those (0.45, 0.6 and 1.2 μL/mL) of MJO. Therefore, the Pickering emulsion composite microparticles seemed to be a promising strategy for enhancing the stability and antibacterial activity of MJO.

Hierarchical mesoporous silicon and albumin composite microparticles delivering DOX and FU for liver cancer treatment

Drug delivery systems based on hydrogel microcarriers have shown enormous achievements in tumor treatment. Current research direction mainly concentrated on the improvement of the structure and function of the microcarriers to effectively deliver drugs for enhanced cancer treatment with decreased general toxicity. Herein, we put forward novel hierarchical mesoporous silicon nanoparticles (MSNs) and bovine serum albumin (BSA) composite microparticles (MPMSNs@DOX/FU) delivering doxorubicin (DOX) and 5-fluorouracil (FU) for effective tumor therapy with good safety. The DOX and FU could be efficiently loaded in the MSNs, which were further encapsulated into methacrylate BSA (BSAMA) microparticles by applying a microfluidic technique. When transported to the tumor area, DOX and FU will be persistently released from the MPMSNs@DOX/FU and kept locally to lessen general toxicity. Based on these advantages, MPMSNs@DOX/FU could observably kill liver cancer cells in vitro, and evidently suppress the tumor development of liver cancer nude mice model in vivo. These results suggest that such hierarchical hydrogel microparticles are perfect candidates for liver cancer treatment, holding promising expectations for impactful cancer therapy.

Comparative Study of Catalytic Activity of Recyclable Au/Fe3O4 Microparticles for Reduction Of 2,4-Dinitrophenol and Anionic, Cationic Azo Dyes.

We synthesized Au/Fe3O4 microparticles. Initially, citrate-capped Fe3O4 micro-sized particles were synthesized by the co-precipitation method with an excess amount of trisodium citrate. Gold ions were reduced on the surface of citrate-capped Fe3O4 and grew as gold sub-microparticles with an average diameter of 210 nm on the surface. The characteristic SPR peak of gold nanoparticles on the surface of Fe3O4 was detected at 584 nm, whereas the absorption in the near-infrared region was increased. SEM images has proved that the synthesized Au/Fe3O4 composite microparticles has an average diameter of 1.7 micrometers. The results of XRD patterns proved the existence of both crystal phases of Fe3O4 and Au particles. To investigate the catalytic activity, the reaction rate constant of reduction of 2,4-dinitrophenol (2,4-DNP) and degradation of Congo red (CR), and methylene blue (MB) with NaBH4 in the presence of Au/Fe3O4 catalyst was monitored by UV-Vis spectroscopy. The initial reaction rate constant calculated from the change in characteristic peak absorptions of 2,4-dinitrophenol was 3.97×10-3 s-1, while the reaction rate constants for the degradation of CR and MB were 9.72×10-3 s-1 and 14.25×10-3 s-1 respectively. After 5 cycles, Au/Fe3O4 microparticles preserved 99 % of the reaction rate constant, exhibiting considerable recycling efficiency in the reduction of nitro groups.

Composite Microparticles from Microfluidics for Chemo-/Photothermal Therapy of Hepatocellular Carcinoma.

Hydrogel microcarrier-based drug delivery systems are of great value in the combination therapy of tumors. Current research directions concentrate on the development of more economic, convenient, and effective combined therapeutic platforms. Herein, we developed novel adhesive composite microparticles (MPPMD) with combined chemo- and photothermal therapy ability via microfluidic electrospray technology for local hepatocellular carcinoma treatment. These composite microparticles consisted of doxorubicin (DOX)-loaded and polydopamine-wrapped mesoporous silicon and alginate. Benefiting from such a strategy of hierarchical structure drug loading, DOX could be gradually released from the system, effectively avoiding the direct toxicity of chemotherapeutics to the body. Additionally, the designed microparticles could not only effectively treat tumors by releasing the chemotherapy drug DOX but also show excellent photothermal properties under the irradiation of near-infrared light, achieving combined chemo- and photothermal treatment effects. Based on these advantages, the MPPMD could remarkably eliminate tumor cells in vitro and enormously restrict tumor development in vivo. These results illustrate that such composite microparticles are ideal combination treatment platforms, possessing promising expectations for cancer therapy.

Reactive Polymer Composite Microparticles Based on Glycidyl Methacrylate and Magnetite Nanoparticles

The modified suspension polymerization technique has been used for the preparation of composite microparticles from the mixture of glycidyl methacrylate (GMA), styrene (S), and divinylbenzene (DVB) in the presence of hydrophobized Fe3O4 nanoparticles. The obtained polymer microspheres were characterized using different instrumental and physicochemical techniques, modified with a zero-order PAMAM dendrimer, and impregnated with palladium(II) acetate solutions to immobilize palladium(II) ions. The resulting materials were preliminarily examined as catalysts in the Suzuki reaction between 4-bromotoluene and phenylboronic acid. It was found that the addition of magnetite particles to the composition of monomers provided polymer microparticles with embedded magnetic nanoparticles. The composite microparticles obtained showed a complex, multi-hollow, or raspberry-like morphology. After their modification, they could serve as recyclable catalysts for reactions that include both 4-bromotoluene and several other aryl bromides.

Functional upcycling of waste PET plastic to the hybrid magnetic microparticles adsorbent for cesium removal

Accumulation of mismanaged plastic in the environment and the appearance of emerging plastic-derived pollutants such as microplastics strongly demand technologies for waste plastic utilization. In this study, polyethylene terephthalate (PET) from waste plastic bottles was directly utilized to prepare a matrix of an adsorbent for cesium (Cs+) removal. The organic matrix of PET-derived oligomers obtained by aminolysis depolymerization was impregnated with bentonite clay and magnetite nanoparticles (Fe3O4 NPs), playing the roles as a major adsorptive medium for Cs+ removal and as a functional component to primarily provide efficient separation of the hybrid adsorbent from aqueous system, respectively. The obtained hybrid composite microparticles were next tested as an adsorbent for the removal of Cs+ cation from aqueous solutions. The adsorption process was characterized by fast kinetics reaching ca. 60% of the equilibrium adsorption capacity within 5 min and the maximum adsorption capacity toward Cs+ was found to be 26.8 mg/g. The adsorption process was primarily dominated by the cationic exchange in bentonite, which was not significantly affected by the admixture of the competing mono- and divalent cations (Na+, K+, and Mg2+). The proposed approach here exploits the sustainable utilization scenario of plastic waste-derived material to template complex multifunctional nanocomposites that can find applications for pollution cleaning and environmental remediation.

Encapsulation of Inorganic Nanoparticles by Anionic Emulsion Polymerization of Diethyl Methylene Malonate for Developing Hybrid Microparticles with Tailorable Composition

Colloidal particle self-assembly into higher-ordered structures has been of great interest due to the promise of creating metamaterials with novel macroscopic properties. The physicochemical properties of these metamaterials can be tailored to achieve composites with tunable functionalities, either by controlling the assembly morphology and/or chemistry of the colloidal building blocks. This work describes a strategy of developing microparticles with a hybrid configuration that have an inorganic and an organic part. The inorganic part comprises functional nanoparticles, which are embedded within an organic polymer particle composed of diethyl methylene malonate polymer [p(DEMM)] prepared using anionic emulsion polymerization. DEMM polymerization is initiated entirely by the presence of hydroxyl anions and the resulting particle diameter can be tuned between 300 nm and 1 micrometer by reaction pH. Inorganic nanoparticles with varying chemistry (TiO2, CdTe, ZnO) can be loaded into the p(DEMM) particle with a controlled weight fraction, as confirmed by thermogravimetric analysis. The colloidal stability of the composite microparticles is seen to be dependent on the ligand coating attached to the inorganic constituent. These results provide a synthetic groundwork for creating hybrid, stimuli-responsive microparticles.

Composite Microparticles of Fat Graft and GFR Matrigel Improved Volume Retention by Promoting Cell Migration and Vessel Regeneration.

The retention volume of autologous fat grafts decreases after transplantation due to limited nutrition infiltration and insufficient blood supply. Structural fat grafts and the 3M (multipoint, multitunnel, and multilayer) injection technique have been considered to improve the survival of grafts; however, it is difficult for surgeons to practice in the clinic because grafts tend to gather into a cluster, especially in large volume fat grafting. Therefore, we hypothesize that prefabricated microparticle fat grafts (PFMG) may improve the retention rate. The C57BL/6 mouse fat particles were embedded in growth factor-reduced (GFR)-Matrigel to detect cell migration by immunofluorescence staining in vitro. PFMG was prepared by mixing mouse fat particles and GFR Matrigel in a 1:1 volume ratio and injected subcutaneously into C57BL/6 mice. Fat particles mixed with PBS in equal volume served as control group. The grafts were harvested at 1, 4, 8, and 12 weeks after sacrifice. The retention rate of grafts at each time point was measured, and the structural alterations were detected by SEM. Fat necrosis and blood vessel density were evaluated by histological analysis. CD34+ cells are migrated from the PFMG and formed a tree-like tubular network in the in vitro study. The retention rate was higher in the PFMG group than in the control group at week 12 (38% vs. 30%, p < 0.05). After transplantation, the dissociated structure of fat particles was maintained in PFMG by SEM analysis. Histological analysis of PFMG confirmed less fat necrosis and more blood vessel density in the PFMG group at the early stage than in the control group. The GFR Matrigel was displaced by adipose tissue with time. In this study, we developed a novel fat grafting method, PFMG that dispersed fat grafts and maintained the structure after transplantation. High volume retention volume of PFMG was achieved by promoting cell migration and vessel regeneration. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Air-through-precursor suction-augmented replica molding for fabrication of anisotropic microparticles in gas-impermeable molds.

Replica molding (REM) is a powerful technique for fabricating anisotropic microparticles. Current REM methods rely on the use of gas-permeable molds for defect-free castings and facile particle recovery. However, they often encounter limitations on either technical accessibility or producible particle diversity. While the use of gas-impermeable molds presents a promising solution to these challenges, particle production within such molds necessitates addressing two critical issues: precursor loading and particle recovery. This study introduces a REM methodology specifically tailored to enable the production of anisotropic microparticles within gas-impermeable molds. To address the issue of precursor loading, our approach incorporates the air-through-precursor suction method, employing a degassed polydimethylsiloxane block to effectively eliminate air bubbles trapped in microwells. Additionally, fluorosilane pretreatment of the mold surface, along with the polyvinyl alcohol film formation, significantly enhances particle recovery up to 249-fold while ensuring particle homogeneity. This methodology demonstrates high adaptability to various gas-impermeable molds and curing techniques. The practical feasibility is illustrated through the successful production of functional composite microparticles that can be effectively utilized for oxygen sensing and self-assembly, challenging in conventional REM.

Recovery of NixMnyCoz(OH)2 and Li2CO3 from spent Li-ionB cathode leachates using non-Na precipitant-based chemical precipitation for sustainable recycling

The interest in recycling spent lithium-ion batteries (Li-ionB) has surged due to the rising demand for valuable metals (e.g., Co, Ni, Li and Mn) and concerns about environmental repercussions emanating from conventional battery waste disposal. Conventional precipitation-based hydrometallurgy recycling processes utilise Na-based or metal-based precipitants. The Na, from Na-based precipitants, is present in high concentrations in the process effluent since they are not recovered during the recycling process. The Na-rich effluent cannot be discarded since it doesn't meet environmental regulations as per the U.S. Environmental Protection Agency (EPA) (2023) therefore creating a storage and disposal problem. It is therefore imperative to utilise non-Na-based precipitants to eliminate the effluent disposal problem. This paper focuses on the recovery of NixCoyMnz(OH)2 and Li2CO3, main precursors for Li-ionB cathode production, from a typical spent Li-ionB cathode (NMC 532) using non-Na precipitant-based chemical precipitation. This study reports NixCoyMnz(OH)2 and Li2CO3 recovery from spent Li-ionBs for closed-loop Li-ionB cathode recycling through an integrated hydrometallurgy and chemical precipitation process. Through the utilisation of leachate solutions comprising 2 M H2SO4 + 6 vol.% H2O2, and a 75 g/L S/L ratio and conducting leaching for 120 min at a temperature of 60 °C and IS of 350 rpm, the recovery efficiency of 98.1 % for Li, 97.1 % for Co, 96.1 % for Ni, and 95.7 % for Mn. The pH of the NMC leachate was initially adjusted to 5 to precipitate Fe, Al and Cu impurities. Thereafter, active metal species (Ni, Mn and Co) were precipitated at a pH of 13 as Ni0.5Co0.2Mn0.3(OH)2 composite microparticles by adding LiOH precipitant. Thereafter, the Li-rich resultant liquor was further used to recover the Li by adding 3.4 mol of CO2 bubbled at 0.068 mol (CO2)/L.min and 40 °C for 45 min. The Li2CO3 precipitates were separated from the suspension through filtration followed by washing using deionised water and hot air drying. The reaction time is 45 mins, and the agitation speed is 150 rpm. Through this multi-stage precipitation process, >98 % of Ni, Co, Mn and > 91 % of Li can be recovered in the form of Ni0.5Mn0.3Co0.2(OH)2 and Li2CO3 respectively. The process exhibits great potential for recovery of valuable materials from spent Li-ionBs. The recovered Ni0.5Co0.2Mn0.3(OH)2 and Li2CO3 materials will be used as precursors in the anhydrous NMC cathode production process.

Preparation, physicochemical characterization and swelling properties of composite hydrogel microparticles based on gelatin and pectins with different structure

Composite hydrogel microparticles based on pectins with different structures (callus culture pectin (SVC) and apple pectin (AU)) and gelatin were developed. Hydrogel microparticles were formed by the ionotropic gelation and electrostatic interaction of COO− groups of pectin and NH3+ groups of gelatin, which was confirmed by FTIR spectroscopy. The addition of gelatin to pectin-based gel formulations resulted in a decrease in gel strength, whereas increasing gelatin concentration enhanced this effect. The microparticle gel strength increased in proportion to the increase in the pectin concentration. The DSC and TGA analyzes showed that pectin-gelatin gels had the higher thermal stability than individual pectins. The gel strength, Ca2+ content and thermal stability of the microparticles based on gelatin and SVC pectin with a lower degree of methylesterification (DM) (14.8 %) were higher compared to that of microparticles based on gelatin and AU pectin with a higher DM (40 %). An increase in the SVC concentration, Ca2+ content and gel strength of SVC-gelatin microparticles led to a decrease in the swelling degree in simulated gastrointestinal fluids. The addition of 0.5 % gelatin to gels based on AU pectin resulted in increased stability of the microparticles in gastrointestinal fluids, while the microparticles from AU without gelatin were destroyed.

Removal of Diclofenac and Heavy Metal Ions from Aqueous Media Using Composite Sorbents in Dynamic Conditions.

Pharmaceuticals and heavy metals pose significant risks to human health and aquatic ecosystems, necessitating their removal from water and wastewater. A promising alternative for this purpose involves their removal by adsorption on composite sorbents prepared using a conventional layer-by-layer (LbL) method or an innovative coacervate direct deposition approach. In this study, four novel composite materials based on a silica core (IS) and a polyelectrolyte coacervate shell were used for the investigation of dynamic adsorption of three heavy metals (lead, nickel and cadmium) and an organic drug model (diclofenac sodium salt, DCF-Na). The four types of composite sorbents were tested for the first time in dynamic conditions (columns with continuous flow), and the column conditions were similar to those used in wastewater treatment plants. The influence of the polyanion nature (poly(acrylic acid) (PAA) vs. poly(sodium methacrylate) (PMAA)), maintaining a constant poly(ethyleneimine) (PEI), and the cross-linking degree (r = 0.1 and r = 1.0) of PEI chains on the immobilization of these pollutants (inorganic vs. organic) on the same type of composite was also studied. The experiments involved both single- and multi-component aqueous solutions. The kinetics of the dynamic adsorption process were examined using two non-linear models: the Thomas and Yoon-Nelson models. The tested sorbents demonstrated good adsorption capacities with affinities for the metal ions in the following order: Pb2+ > Cd2+ > Ni2+. An increase in the initial diclofenac sodium concentration led to an enhanced adsorption capacity of the IS/(PEI-PAA)c-r1 sorbent. The calculated sorption capacities were in good agreement with the adsorption capacity predicted by the Thomas and Yoon-Nelson models. The substantial affinity observed between DCF-Na and a column containing composite microparticles saturated with heavy metal ions was explained.

A sustainable waterproof temperature sensor made with single-use-packets and enhancement of its sensing performance by depositing the g-C3N4/BiOBr composite on its surface

Currently, flexible temperature sensors are highly demanded for processes in the food industry. However, they have a high cost and most of them detect temperatures only below 80 °C. To fabricate temperature sensors at lower cost, temperature sensors were fabricated by printing graphene ink on recycled plastics (obtained from single-use-packets). Firstly, sensors made exclusively with graphene were tested for the temperature detection, but no detection signal was obtained. Subsequently, the sensors were coated with g-C3N4 (gCN)/BiBrO composite microparticles and those ones produced response times of 8–12.2 s when they are detecting temperatures of 60–120 °C in air. For this same detection range, the recovery times varied from 19 to 27.6 s. The sensors were also tested in hot water and detected temperatures of 60–92 °C. Interestingly, lower response/recovery times of 5–7.8/7–14.7 s were obtained in comparison with the sensors used in air. The surface of the sensors exposed to different temperatures was also analyzed by Raman and XPS techniques. After this, we found that the highest amount of defects (oxygen vacancies) are present in the sensor used for the temperature detection of 90 °C. If the temperature detection is increased to 120 °C, graphene oxide is formed on the sensor's surface as well as Bi-O-C and Br-C bonds. Those ones indicate a better chemical linking between the gCN/BiBrO and the graphene layer, which in turn, favored the electron transport through the sensor and lowered the response time at high temperatures. In general, the results of this research indicate that recycled plastics can be used for the fabrication of inexpensive waterproof temperature sensors, which can operate in air or underwater. The sensors studied here could be of interest for the food industry or for the monitoring of temperatures under rain.

Microwave plasma-produced Al/Al2O3 microparticles as precursors for high-temperature high-strength composites

Microwave plasma-produced Al/Al2O3 microparticles as precursors for high-temperature high-strength composites

Characteristics of Microparticles Based on Resorbable Polyhydroxyalkanoates Loaded with Antibacterial and Cytostatic Drugs.

The development of controlled drug delivery systems, in the form of microparticles, is an important area of experimental pharmacology. The success of the design and the quality of the obtained microparticles are determined by the method of manufacture and the properties of the material used as a carrier. The goal is to obtain and characterize microparticles depending on their method of preparation, the chemical composition of the polymer and the load of the drugs. To obtain microparticles, four types of degradable PHAs, differing in their chemical compositions, degrees of crystallinity, molecular weights and temperature characteristics, were used (poly-3-hydroxybutyrate and copolymers 3-hydroxybutyric-co-3-hydroxyvaleric acid, 3-hydroxybutyric-co-4-hydroxybutyric acid, and 3-hydroxybutyric-co-3-hydroxyhexanoic acid). The characteristics of microparticles from PHAs were studied. Good-quality particles with an average particle diameter from 0.8 to 65.0 μm, having satisfactory ζ potential values (from -18 to -50 mV), were obtained. The drug loading content, encapsulation efficiency and in vitro release were characterized. Composite microparticles based on PHAs with additives of polyethylene glycol and polylactide-co-glycolide, and loaded with ceftriaxone and 5-fluorouracil, showed antibacterial and antitumor effects in E. coli and HeLa cultures. The results indicate the high potential of PHAs for the design of modern and efficient drug delivery systems.

A rational strategy for directly synthesizing strongly yellow solid-state fluorescent-emitting carbon nanodots composite microparticles by structure regulation

Carbon nanodots (CDs) have received huge attention of researchers due to their good optical properties. However, CDs generally suffer from severely fluorescence self-quenching once they are aggregated or in solid state, limitating their applications in light-emitting devices. In this work, we report a rational strategy for synthesis of yellow fluorescent carbon nanodots (Y-CDs)-based microparticles with a high solid-state photoluminescence quantum yield (32.02%). It is the first report on designing a lamellar structured matrix to disperse CDs to realize long-wavelength solid fluorescence. The matrix is confirmed as p-phenylenediamine dihydrochloride by X-ray diffraction (XRD). 3-glycidyloxypropyltrimethoxysilane (KH-560) acts as a bridge to connect CDs to the matrix based on epoxy-amine reaction and silane hydrolysis condensation for uniform dispersion of CDs and high solid-state luminescence can be easily achieved. Meanwhile, through adjusting the amount of KH-560, the morphology of Y-CDs-based microparticles can be controlled from cube to layered structure and the fluorescence intensity can be significantly improved. Importantly, the optimal Y-CDs particles can be combined with blue chips (450 nm) to fabricate high-performance white light-emitting diodes (WLEDs) without using commercial phosphor, and the constructed WLEDs exhibit a high color rendering index (CRI) of 84.2.