Core-shell Structured Microspheres Research Articles

An improved preparation method of core-shell Al@Sn-Bi microspheres and its microstructure formation mechanism

This paper presents an improved method for achieving controllable preparation of the composition and size of the monotectic alloy core-shell structure microspheres. This advancement is expected to enhance the commercial application of monotectic alloy core-shell structure microspheres. By installing a heating device at the top of the drop tube in the pulsated orifice ejection method setup, we achieved in-situ heat treatment of falling droplets, resulting in the successful preparation of Al45(Sn42Bi58)55 core-shell structure microspheres. Furthermore, we investigated the formation mechanism of the Al@Sn-Bi core-shell structure. Nine sets of Al-Sn-Bi microspheres with varying in-situ heat treatment temperatures were prepared. Analysis via X-ray diffraction and transmission electron microscopy revealed that the microspheres consisted of Al-rich, Sn-rich, and Bi-rich phases, without any intermetallic compounds. Scanning electron microscopy results indicated that as the in-situ heat treatment temperature increased, the structure of the Al-Sn-Bi microspheres transitioned from irregular to regular core-shell configurations. This suggests that higher heat treatment temperatures prolong liquid phase separation time, leading to increased repetition of Marangoni motion within the droplet, Ostwald ripening of the minor phase droplets, and Soret effect of the matrix phase. However, at temperatures exceeding 700 °C, the solidification rate of alloy droplets decreased, causing the Al-rich phase core to deviate from the center and form a crescent structure due to Stokes motion.

Core-Shell Microspheres Prepared Using Coaxial Electrostatic Spray for Local Chemotherapy of Solid Tumors.

Local chemotherapy is an alternative therapeutic strategy that involves direct delivery of drugs to the tumor site. This approach avoids adverse reactions caused by the systemic distribution of drugs and enhances the tumor-suppressing effect by concentrating the drugs at the tumor site. Drug-loaded microspheres are injectable sustained-release drug carriers that are highly suitable for local chemotherapy. However, a complex preparation process is one of the main technical difficulties limiting the development of microsphere formulations. In this study, core-shell structured microspheres loaded with paclitaxel (PTX; with a core-shell structure, calcium alginate outer layer, and a poly (lactic acid-co-glycolic acid) copolymer inner layer, denoted as PTX-CA/PLGA-MS) were prepared using coaxial electrostatic spray technology and evaluated in vitro and in vivo. PTX-CA/PLGA-MS exhibited a two-stage drug release profile and enhanced anti-tumor effect in animal tumor models. Importantly, the preparation method reported in this study is simple and reduces the amount of organic solvent(s) used substantially.

Multifunctional Nanofibrous Scaffolds Capable of Localized Delivery of Theranostic Nanoparticles for Postoperative Cancer Management.

Postoperative recovery of cancer patients can be affected by complications, such as tissue dysfunction or disability caused by tissue resection, and also cancer recurrence resulting from residual cancer cells. Despite impressive progress made for tissue engineering scaffolds that assist tissue regeneration for postoperative cancer patients, the majority of existing tissue engineering scaffolds still lack functions for monitoring and killing residual cancer cells, if there are any, upon their detection. In this study, multifunctional scaffolds that comprise biodegradable nanofibers and core-shell structured microspheres encapsulated with theranostic nanoparticles (NPs) are developed. The multifunctional scaffolds possess an extracellular matrix-like nanofibrous architecture and soft tissue-like mechanical properties, making them excellent tissue engineering patch candidates for assisting in the repair and regeneration of tissues at the cancerous sites after surgery. Furthermore, they are capable of localized delivery of theranostic NPs upon quick degradation of core-shell structured microspheres that contain theranostic NPs. Leveraging on folic acid-mediated ligand-receptor binding, surface-enhanced Raman scattering activity, and near-infrared-responsive photothermal effect of the theranostic gold NPs (AuNPs) delivered locally, the multifunctional scaffolds display excellent active targeting, diagnosis, and photothermal therapy functions for cancer cells, showing great promise for adaptive postoperative cancer management.

Microstructure evolution and mechanical properties of 3YSZ/Ni composites with uniform phase distribution prepared by core-shell structure microspheres

Yttrium-stabilized zirconia(3YSZ) microspheres with different size ranges were prepared by sol-gel method, followed by electroless Ni plating on their surfaces. The as-prepared core-shell structure 3YSZ/Ni microspheres were then spark plasma sintered (SPS) into 3YSZ/Ni composites, in which a uniform distribution of ceramic and metal phases was achieved. The underlying correlations among microsphere size, Ni concentration, microstructure, and resultant mechanical properties were experimentally analyzed. Results show that: continuous and smaller microsphere sizes can obtain relatively high-density samples with good mechanical properties, which can be proved by the Minimum Solid Area (MSA) model. 3YSZ sample prepared with the optimized microsphere size range of 0–50 μm exhibits the highest relative density and fracture toughness of 98.8% and 5.51 ± 0.33 MPa·m1/2, respectively. Furthermore, the core-shell structure 3YSZ/Ni microspheres with varying Ni contents exhibited a uniform composite of flakes and particles Ni metal after sintering, among which 3YSZ/10 wt%Ni composites have achieved better mechanical properties, with density, hardness and fracture toughness of 96.9%, 8.61 ± 0.35 GPa, 7.92 ± 0.71 MPa·m1/2, respectively. Firstly, the uniformly dispersed Ni metal flakes or particles provide multiple toughening effects, including crack bridging, pull-out, interfacial debonding, crack deflection, etc. Secondly, due to residual stress, cracks tend to deflect near Ni metal, extending the crack path. Thirdly, the 3YSZ matrix's transition from an intergranular to a transgranular fracture also increases fracture energy consumption. Compared to the pure 3YSZ sample with a wide microsphere size range of 0–100 μm, the fracture toughness of 3YSZ/10 wt%Ni composites with a microsphere size of 0–50 μm is increased by 73.9%.

Functional microspheres for tissue regeneration.

As a new type of injectable biomaterials, functional microspheres have attracted increasing attention in tissue regeneration because they possess some advantageous properties compared to other biomaterials, including hydrogels. A variety of bio-inspired microspheres with unique structures and properties have been developed as cellular carriers and drug delivery vehicles in recent years. In this review, we provide a comprehensive summary of the progress of functional and biodegradable microspheres that have been used for tissue regeneration over the last two decades. First, we briefly introduce the biomaterials and general methods for microsphere fabrication. Next, we focus on the newly developed technologies for preparing functional microspheres, including macroporous microspheres, nanofibrous microspheres, hollow microspheres, core-shell structured microspheres, and surface-modified functional microspheres. After that, we discuss the application of functional microspheres for tissue regeneration, specifically for bone, cartilage, dental, neural, cardiac, and skin tissue regeneration. Last, we present our perspectives and future directions of functional microspheres as injectable carriers for the future advancement of tissue regeneration.

Spray pyrolysis-derived MoO3@Al2O3@TiO2 core-shell structures with enhanced hydrodeoxygenation performance

Developing highly active and stable hydrodeoxygenation (HDO) catalysts is an industrial challenge. In this work, γ-Al2O3 microspheres incorporating high levels of Mo catalyst (30 wt%; MoO3@Al2O3) were effectively and rapidly prepared by ultrasonic-assisted spray pyrolysis. The MoO3@Al2O3 microspheres were then decorated by a hydrophobic TiO2 layer to obtain core–shell-structured microspheres dubbed MoO3@Al2O3@TiO2. HDO experiments revealed that catalysis by reduced MoO3@Al2O3@TiO2 microspheres afforded ~96% palmitic acid (PA) conversion and ~ 67% hydrocarbon selectivity, surpassing the uncoated catalyst. Furthermore, the prepared TiO2-coated MoO3@Al2O3 microspheres retained excellent HDO catalytic activity under water-containing feed for 24 h. This study's results suggest that combining spray pyrolysis and coating with a TiO2 shell produces a synergetic effect that enhances the catalyst's activity and stability.

Scalable Synthesis of Pore-Rich Si/C@C Core-Shell-Structured Microspheres for Practical Long-Life Lithium-Ion Battery Anodes.

Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid-electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g-1 at 100 mA g-1, and excellent cycle performance with a capacity of 708.6 mAh g-1 and 87.1% capacity retention after 820 cycles at 1000 mA g-1, outperforming the reported results of Si/C composite anodes. Furthermore, a low electrode swelling of 18.1% at a high areal capacity of 3.8 mAh cm-2 can be obtained. When assembled into a practical 3.2 Ah cylindrical cell, extraordinary long cycling life with a capacity retention of 81.4% even after 1200 cycles at 1C (3.2 A) and excellent rate performance are achieved, indicating significant advantages for long-life power batteries in electric vehicles.

Synthesis and Application of Recyclable Core-Shell Structure Microspheres Mcts-G-At in Detection of Hg(Ⅱ) in Aquatic Products

The MCTS-g-AT was developed as a novel magnetic adsorbent with core-shell structure. Its unique synthesis route endows MCTS-g-AT with green, convenient, economical and safe characteristics, and also good selective adsorption of Hg(Ⅱ). The material was characterized using an appropriate set of spectroscopic and analytical techniques (SEM, EDS, XRD, VSM, FTIR and TGA). Its adsorption kinetics fits the pseudo-secondary model well and adsorption isotherm fits the Langmuir equation well, suggesting the main adsorption mechanism of chemisorption with monolayer adsorption. The results of the thermodynamic parameters indicate that the adsorption process is spontaneous and endothermic. Column adsorption experiments showed that the maximum adsorption capacity of Hg(II) was 207.6 mg/g (298 K). Moreover, the Hg(II) adsorbed on composite microspheres was completely eluted by 3 mol/L HNO 3 or 4 mol/L HCl. Furthermore, MCTS-g-AT adsorption column combined with spectrophotometer can achieve more accurate detection of Hg(II) in aquatic products.

Study on novel Fe-based core-shell structured soft magnetic composites with remarkable magnetic enhancement by in-situ coating nano-ZnFe2O4 layer

Soft magnetic composites based on spherical supersendust (Fe85Si8Al4Ni3) powder were made by gas atomization. The nano-ZnFe2O4 layer was coated on the surface of Fe85Si8Al4Ni3 powder particles by in-situ oxidation. Core-shell structured microspheres were achieved and then mixed with epoxy-modified silicone resin. Lorentz-transmission electron microscopy confirmed the core-shell structure of the Fe85Si8Al4Ni3-ZnFe2O4 microspheres. The uniform surface layer consisted of nano-ZnFe2O4 layer was clarified by scanning electron microscopy and energy dispersive spectroscopy X-ray analysis. The ferromagnetic nano-ZnFe2O4 layer effectively reduces magnetic dilution, while high electrical resistivity of both ZnFe2O4 and ESR provides satisfactory insulation of the SMCs, giving rise to simultaneous high permeability and extraordinary low core loss. Magnetic properties were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials (SY8258B-H/m). The results show that the samples prepared at 1200 MPa and 550 ℃ exhibited distinguished magnetic properties, with core loss of 89 W/kg (100 kHz, 50 mT) and amplitude permeability of 50 whose frequency stability is up to 170 kHz. The Fe85Si8Al4Ni3 SMCs with excellent soft magnetic properties provide great potential for application of various fields such as transformers, sensors and electromagnetic actuation devices. Our approach can be expanded to other Fe-based SMCs.

Magnetic supported ionic liquid catalysts with tunable pore volume for enhanced deep oxidative desulfurization

Magnetic core-shell structure microspheres with tunable pore volumes were synthesized and used to immobilize a polyoxometalate-based ionic liquid for oxidative desulfurization of diesel fuel. The as-prepared catalysts were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and nitrogen adsorption–desorption. The results showed that the small catalyst had a large pore volume and the large catalyst had a small pore volume, while their BET surface areas and pore sizes were almost the same. Compared with the large catalyst, the small catalyst showed better catalytic activity, probably due to the promotion of its large pore volume. Under the optimal reaction conditions, the removal of 4,6-dimethyldibenzothiophene could reach 95.4% with a residual sulfur content of 9.2 mg kg−1. After the reaction, the catalyst could be separated by a magnetic field and recycled at least 7 times with little decrease in desulfurization efficiency.

Morphology and blowing agent encapsulation efficiency of vinylidene chloride copolymer microspheres synthesized by suspension polymerization in the presence of a blowing agent

ABSTRACTPolymer microspheres were synthesized by the suspension copolymerization of vinylidene chloride (VDC), acrylonitrile (AN), and/or methyl methacrylate (MMA) in the presence of a paraffin blowing agent. The effects of the monomer composition, crosslinking agent content, blowing agent type, and content on the morphology and blowing agent encapsulation efficiency of the microspheres were investigated. The porous and non‐core–shell structure microspheres with a low encapsulation efficiency of blowing agent were formed when VDC was copolymerized with individual AN or MMA, whereas microspheres with a good core–shell structure and a high encapsulation efficiency of blowing agent were formed when the feeding monomer mass ratios of VDC–AN–MMA were 50/20/30, 60/20/20, and 70/20/10. The addition of 0.2–0.4 wt % divinyl benzene crosslinking agent (on the basis of monomer mass) was favorable to the formation of core–shell structure microspheres with a high encapsulation efficiency of blowing agent. Microspheres with wrinkled surfaces and a pronounced internal topography were formed as the carbon atom number of paraffin increased from 5 to 7. The encapsulation efficiency of blowing agent increased as the carbon atom number and content of paraffin blowing agent increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44376.

Coaxial electrospray for cell encapsulation and delivery in cell-based tissue engineering

Event Abstract Back to Event Coaxial electrospray for cell encapsulation and delivery in cell-based tissue engineering Yu Zhou1*, Qilong Zhao1* and Min Wang1 1 The University of Hong Kong, Mechanical Engineering, Hong Kong, SAR China Introduction: For human body tissue regeneration, different approaches, including scaffold-based[1], growth factor-based[2] and cell-based tissue engineering[3], are explored. In cell-based tissue engineering, developing appropriate vehicles for cell encapsulation and delivery is highly important. The process of cell encapsulation must be cell-friendly for achieving high cell viability. Moreover, for microspherical delivery vehicles, the diameter of cell-encapsulated microspheres is a critical factor. The diameter should not be too small or too large. Degradation properties of polymers for microspheres are another important factor for cell delivery. Coaxial electrospray can produce core-shell structured microspheres and hence was investigated in this study for the encapsulation and delivery of cells. Materials and Methods: To determine suitable electrospray parameters, solid, cell-free microspheres were made first by electrospray using polymer solutions of sodium alginate (SA), poly(vinyl alcohol), gelatin and mixed solutions (1:1) of two polymers. Then, cell-free microspheres with core-shell structure were produced by coaxial electrospray where a polymer solution was fed into outer tube and PBS was fed into inner tube of the coaxial nozzle. After process optimization, PBS was replaced by aqueous cell suspensions of human umbilical vein endothelial cells (HUVECs) in coaxial electrospray for making cell-encapsulated microspheres. The morphology and structure of cell-free and cell-containing microspheres were studied. The viability of HUVECs was studied using live and dead assay. Triggered cell release was also investigated. Results and Discussion: Electrospray experiments showed that relatively large diameter (~5 micron) and uniform microspheres could be produced using mixed polymer solution of SA and gelatin. Therefore, coaxial cell electrospray was conducted using HUVEC cell suspensions and SA/gelatin polymer solution or SA solution alone, and a post-spray cross-linking treatment was added for the polymer shell. After further explorations, electrospray parameters (applied voltage, feeding rate ratio between the outer tube and inner tube, etc.) were fixed for fabricating cell-encapsulated microspheres. HUVECs with low cell density (5×106 cells/mL) and high cell density (1×107 cells/mL) were used for encapsulation. Fig.1 shows cell-encapsulated microspheres made by coaxial electrospray and post-spray crosslinking using different cell densities. Microspheres with regular spherical shape could be produced for both low cell density and high cell density. A higher cell loading efficiency was attained for microspheres using a higher cell density. Triggered cell release was achieved by treating cell-encapsulated microspheres with a 0.05M sodium citrate solution. The polymer shell of microspheres was dissolved gradually and after 10 minutes, polymer shell disappeared and cells were totally released (Fig.2). Conclusion: Coaxial electrospray proved to be a useful and adaptable technique for making cell delivery vehicles. With process optimization, sufficient cells could be encapsulated in core-shell structured microspheres via coaxial electrospray. Cells contained in the core of microspheres were well protected and showed high viability after the electrospray process. Triggered release could be realized for delivering live cells, enabling cell-based therapies. This work was supported by Hong Kong Research Grants Council through a GRF Grant (HKU 717713E).

Novel core-shell structure microspheres based on lanthanide complexes for white-light emission and fluorescence sensing.

A series of new core-shell structure materials based on lanthanide complexes [H2NMe2]3[Ln(dpa)3] (Ln = Eu, Tb, Sm, Dy, Nd, and Yb; [H2NMe2](+) = dimethylamino cation; dpa = 2-dipicolinate) and silica microspheres has been prepared under solvothermal conditions. Electron microscopy reveals that the nanosized materials SiO2@Ln-dpa are spherical with a narrow size distribution and a [H2NMe2]3[Ln(L)3] coating was generated on the surface of silica microspheres successfully. The core-shell structure materials exhibit excellent optical performance. The white-light-emitting material SiO2@(Dy:Eu)-dpa has a potential application in the development of a white-light device, as a result of the fact that its CIE chromaticity coordinate is very close to that of pure white. Then, we selected SiO2@Eu-dpa as a representative sample for sensing experiments. Eventually, we found that the core-shell structure sensors are highly selective and sensitive for acetone and Cu(2+) cations. The detection of Cu(2+) in the human body is an important issue. Interestingly, the core-shell structure materials display better selectivity and higher sensitivity than the pure lanthanide complexes in sensing Cu(2+) and the value of the quenching effect coefficient has increased by more than 20%.

Dynamic control of the location of nanoparticles in hybrid co-assemblies.

We herein demonstrated an approach to control the spatial distribution of components in hybrid microspheres. Hybrid core-shell structured microspheres (CSMs) prepared through co-assembly were used as starting materials, which are comprised of anthracene-ended hyperbranched poly(ether amine) (AN-hPEA) in the shell and crystallized anthracene containing polyhedral oligomer silsesquioxane (AN-POSS). Upon thermal annealing at a temperature higher than the melting point of AN-POSS, the diffusion of AN-POSS from the core to the shell of CSM leads to a transition of morphology from the core-shell structure to core-transition-shell to the more stable homogeneous morphology, which has been revealed by experimental results of TEM and DSC. The mechanism for the morphology transition of CSM induced by the diffusion of AN-POSS was disclosed by a dissipative particle dynamics (DPD) simulation. A mathematical model for the diffusion of POSS in the hybrid microsphere is established according to Fick's law of diffusion and can be used to quantify its distribution in CSM. Thus, the spatial distribution of POSS in the microsphere can be controlled dynamically by tuning the temperature and time of thermal annealing.

Preparation and enhanced microwave absorption properties of Ni microspheres coated with Sn6O4(OH)4 nanoshells

In this work, core-shell structured microspheres with Ni cores and Sn6O4(OH)4 nanoshells have been successfully synthesized by a solvothermal deposition method. The crystal structure, microstructures and electromagnetic (EM) properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, energy disperse X-ray spectrometry, Fourier transform infrared (FT-IR), transmission electron microscope (TEM) and a network analyser. The Ni/Sn6O4(OH)4 composite microspheres show better microwave absorption properties than those of pure Ni microspheres. An obvious multiple reflection loss phenomenon was observed with the increase of matching thickness. A minimal reflection loss (RL) as low as −32.4dB was observed at 13.2GHz with the absorber thickness of 5.0mm. The enhanced microwave absorption performances of Ni/Sn6O4(OH)4 composite microspheres were due to good electromagnetic impedance match, geometrical factors, and unique core-shell structure.

Controllable synthesis and optical properties of SnO 2 core‐shell microspheres

SnO2 core-shell microspheres were synthesised via a hydrothermal method with hexamethylenetetramine as a surfactant. The structure and the morphology of the products were characterised by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The results indicated that the overall dimension of the core-shell microspheres and the diameter of the spherical nuclei could be adjusted by changing the concentration of NaOH and hexamethylenetetramine or the reaction time. Based on the time dependent reactions, a possible growth mechanism is proposed. It is believed that the Kirkendall effect plays an important role in the formation of the core-shell structure. The optical properties of the core-shell structure microspheres were also studied through the photoluminescence and the Raman spectra.

Preparation and enhanced photocatalytic activity of CdS@RGO core–shell structural microspheres

Reduced graphene oxide (RGO) wrapped CdS microspheres with enhanced photocatalytic activity were successfully synthesized via a two-step hydrothermal method. The as-prepared samples were carefully characterized by X-ray diffraction, scanning electron microscopy and Raman spectrometer. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) under visible light irradiation. Due to its large surface area and stepwise structure of energy level, which result in the efficiently enhancing of the adsorption performance of dye molecules and suppressing of the charge recombination of photocatalytst, a remarkably enhanced degradation rate of RhB dye about 95.2% within 50 min has been observed. In addition, the introduction of the graphene shell could effectively protect the internal CdS microsheres from photocorrosion, and the composite showed an excellent recyclability property for its photocatalytic applications.

Preparation and characterization of high-content aripiprazole-loaded core-shell structure microsphere for long-release injectable formulation.

The aim of this study was to obtain injectable high-drug-loading core-shell structure microspheres that release aripiprazole over 2 months. The microparticles were prepared by the oil-in-water emulsion solvent evaporation method and characterized. The microparticles were prepared with aripiprazole and 3 types of poly(lactic acid) (PLA) (DL-PLA: molecular weight (MW), ca. 20000; DL-PLA: MW, ca. 95000; or L-PLA: MW, ca. 110000), which were dissolved within the organic phase, and prepared in 3 temperature conditions for the external aqueous phase (two fixed temperature conditions and a gradually increased temperature condition). The theoretical drug loading in the particles was set to 80%. When prepared at fixed temperature conditions, all of the microparticles that were prepared with the 3 types of PLA were not spherical or smooth-surfaced. These microparticles released 100% of the drug within 1 week in the in vitro study. However, the microparticles that were prepared with DL-PLA (MW, 95000) in the gradually increased temperature condition were spherical with a smooth surface. The dissolution profile of the microparticles showed a long release over 7 weeks in vitro. The actual drug loading in the microspheres was 73-80%. A core-shell structure was observed in the inner structure of the microspheres. The core-shell microspheres were injected subcutaneously into rabbits. Aripiprazole was detected in the serum over 12 weeks. Production of high-drug-loading core-shell structure microspheres was successfully achieved by using high molecular weight of PLA and specific temperature condition at preparation. It showed long release profile in vitro and in vivo.

Oil Column Method for Magnetic Microspheres with Core-Shell Structure

Spherical alumina catalysts have been widely used in fluidized bed and slurry-bed or catalyst carrier due to their excellent pore structure, large surface area, good physical strength and resistance to acids and stability. Magnetic microspheres of γ-Fe2O3 @ Al2O3 with core-shell structure were obtained by γ-Fe2O3 magnetic core coating with aluminum sol. After aging, drying and calcinations process, microspheres with certain hardness and magnetic properties can be obtained. During the preparation of core-shell structure microspheres, effect of both the content of aluminum sol, hexamethylenetetramine(HMT), magnetic core γ-Fe2O3 and process parameters of shaping time, aging temperature, calcination temperature on the properties of the spherical carrier was investigated. The optimum properties of microsphere carrier for hardness of 36.32 N/mm, specific surface area of 89.016 m2/g, pore volume of 0.874 cm3/g and average pore diameter 18.51 nm were synthesized, respectively.

Synthesis of a new type of echinus-like Fe3O4@TiO2 core–shell-structured microspheres and their applications in selectively enriching phosphopeptides and removing phospholipids

Some compounds of low abundance in biological samples play important roles in bioprocesses. However, the detection of these compounds at inherently trace concentrations with interference from a complex matrix is difficult. New materials for sample pretreatment are essential for the removal of interferences and for selective enrichment. In this study, echinus-like Fe3O4@TiO2 core–shell-structured microspheres (echinus-like microspheres) have been synthesized for the first time. Rutile phase TiO2 nanorods with a length of approximately 300nm and width of approximately 60nm are arranged regularly on the surface of the microspheres. This novel type of material exhibited good selectivity and adsorption capacity toward phosphate-containing compounds. In proteomics research, the echinus-like microspheres were used to selectively enrich phosphopeptides from complex peptide mixtures. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) analysis showed that fourteen phosphopeptides were detected from α-casein tryptic digests after enrichment. Even in peptide mixtures that contained highly abundant nonphosphorylated peptides with interference from bovine serum albumin, these phospopeptides could still be selectively trapped with little nonspecific adsorption. In metabolomics studies, the echinus-like microspheres were further used to selectively remove phosphocholines (PCs) and lysophosphocholines (LPCs), which are the main matrix interferences for the detection of metabolites of low abundance in plasma. Liquid chromatography–quadrupole time-of-flight mass spectrometry was used to perform the metabolic profiling of plasma. The high concentrations of PCs and LPCs were effectively eliminated, and many endogenous metabolites of low abundance were enhanced or even observed for the first time. All of the results suggest that echinus-like microspheres have potential applications in proteomics and metabolomics to improve the detection sensitivity of important compounds.