Functional, uniform, and macroporous latex particles: Preparation, electron microscopic characterization, and nonspecific protein adsorption properties

The Novel Polymethacrylate Based Hydrophilic Stationary Phase for Ion Chromatography

Ion chromatography is widely used as a useful and powerful tool for the analysis of anionic and cationic components found in waters and aqueous media. The performance and selectivity of ion chromatography are based on the stationary phase column packed material. In this study, it is aimed to develop new column material with quaternary ammonium functional group based on monodisperse polymeric particles for ion chromatography and to investigate their chromatographic performance. For the analysis of inorganic anions by ion chromatography, new stationary phases macroporous monodisperse particles based on 3-chloro-2-hydroxy propylmethacrylate-co-ethylene dimethacrylate are obtained as column packing material. 3-chloro-2-hydroxy propylmethacrylate and ethylene glycol dimethacrylate are transformed to porous monodisperse particle form by using glycidyl methacrylate as the seed latex and ethyl benzene as the porogen solvent via micro-suspension polymerization technique. Then macroporous monodisperse particles surface is functionalized by triethylamine so strong anion exchange is obtained for ion chromatography packing material. A series of stationary phases prepared from polymer particles containing different amounts of porogen solvent were tested. The results show that column packing material is successful to separate inorganic anions mixture such as F−, Cl−, NO2−, Br−, NO3− by using the carbonate and bicarbonate solutions as mobile phases.

Tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres: Synthesis, characterization, and application in protein separation

Effective protein adsorption by solid matrices from complex biological samples has attracted attention for broad application in biomedical field. Immobilization of calixarenes to solid supports is an essential process for their application in protein separation and purification. Silica is the most widely used support material in calixarene immobilization. With high concentration of polymer microspheres as templates, the large pore mesoporous silica microspheres with controllable, uniform size and structure were successfully synthesized and the resulting large pore mesoporous silica microspheres were modified with water-soluble tetrasulfonate calix[4]arene of unique hollow cavity-shaped structure. The tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres (SCLX4@LPMS) were characterized by diverse analytical techniques and their protein adsorption performance were also investigated. The obtained SCLX4@LPMS gave rise to an adsorption efficiency of >90% for cytochrome c and lysozyme within a wide pH range of 3.0-10.0 and possessed remarkably high adsorption capacity of cytochrome c (363.64 mg g^-1) and lysozyme (166.11 mg g^-1). The retained cytochrome c and lysozyme can be readily eluted by using phosphate buffer solution containing NaCl as a stripping reagent with the recoveries of 81% and 86% after 5 times enrichment, respectively. The SCLX4@LPMS microspheres have been applied for the selective adsorption of proteins in real samples and had the application potential in protein adsorption, drug delivery, biosensors, and other biomedical fields.

Hydrophilic Submicron Nanogel Particles for Specific Recombinant Proteins Extraction and Purification

In biomedical diagnosis and bionanotechnologies, the extraction and purification of proteins and protein derivatives are of great interest. In fact, to purify recombinant proteins for instance, new methodologies and well appropriate material supports need to be established and also to be evaluated. In this work, hydrophilic nanohydrogel particles were prepared for recombinant proteins extraction for purification purpose. The prepared nanohydrogel polymer-based particles are hydrophilic below the volume phase transition temperature (TVPT) and dehydrated above the TVPT, due to the thermally sensitive poly(N-alkyl acrylamide) and poly(N-alkyl methacrylamide) derivatives. Then, the use of heavy metal ions in the presence of such functional particles should specifically capture recombinant proteins (i.e., proteins bearing a poly(histidine) part). In order to understand and to optimize the specific capture and the purification of recombinant proteins, various parameters have been investigated as a systematic study. Firstly, the adsorption was investigated as a function of pH and protein concentration. According to high hydration of the prepared nanohydrogel, no marked adsorption was observed. Secondly, the effect of pH was investigated and found to be the driven parameter affecting the metal ions immobilization and the recombinant proteins complexation. As a result, high protein complexation was observed at basic pH compared to non-complexation at acidic pH medium. The immobilized proteins via complexation were released by changing the pH. This decomplexation seems to be effective but depends on fixation conditions and particle surface structure.

Microfluidic synthesis of monodisperse porous polystyrene microspheres for sorption of bovine serum albumin

Droplet microfluidics offers exquisite control over the flows of multiple fluids in micro-scale, enabling fabrication of advanced microspheres with precisely tuneable structures. The main goal of this work was to design monodispersed carboxylated polystyrene microspheres with a developed pore structure (a specific surface area more than 200 m²/g) using microfluidic technology. We investigated the influence of the composition of monomer phase for the stable formation of droplets. Under the stable region, the resulting microspheres (with diameter 50 µm) showed narrow size distribution having a coefficient of variation of below 2%. The obtained microspheres are characterised by morphology and surface structure by means of electron microscopy. The structure of cross-linked microspheres is investigated by solid-state ¹H NMR spectroscopy. Finally, these microspheres have great potential for the effective sorption of biologically active substances (bovine serum albumin).

Surface-imprinted silica particles for Concanavalin A purification from Canavalia ensiformis

Concanavalin A is a representative of the plant protein group known as lectins. Many lectin proteins have useful characteristics for studies on cell division and cell surfaces. In this study, a new adsorbent for the specific separation of Concanavalin A was prepared by applying a silica particle surface imprinting method. First, silica particles were activated via acidic treatment, and then, 3-methacryloyloxypropyl trimethoxysilane (MPTMS) was used for modification. For the preparation of Concanavalin A surface-imprinted silica particles (Con A-MISPs), N-methacryloyl-l-histidine methyl ester (MAH) was used as a functional monomer. The silica particles were characterized using a Zetasizer, scanning electron microscopy equipment (SEM), and Fourier transform infrared spectroscopy (FTIR). The effects of parameters such as the pH, initial concentration of Concanavalin A, and temperature on the adsorption of Concanavalin A were determined. The maximum Concanavalin A adsorption onto Con A-MISPs was observed to be 305.2 mg/g at a pH of 6. The reusability of the Con A-MISPs was approximately 93.5%. The non-imprinted silica particles (NISPs) were prepared in the same manner without Concanavalin A to compare the surface imprinting factor. Selective binding studies were carried out with lysozyme and hemoglobin molecules. The selectivity of the Con A-MISPs was also investigated by isolating Concanavalin A from Canavalia ensiformis. The purity of the Concanavalin A was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE).

TEMPO-oxidized cellulose nanofiber (TOCN) decorated macroporous silica particles: Synthesis, characterization, and their application in protein adsorption

Effective protein adsorption has attracted attention for broad application in the biomedical field. In this study, we introduce the synthesis of a TEMPO-oxidized cellulose nanofiber (TOCN) decorated macroporous SiO₂ (TOCN@macroporous SiO₂) particle and its protein adsorption performance. The TOCN@macroporous SiO₂ particles have a unique cellulose nanofiber network structure on the macroporous, highly-negative zeta potential (-62 ± 2 mV) and high surface area (30.8 m²/g) for dried-state cellulose based particles. These characteristics provide sites that are rich in electrostatic interaction to exhibit an outstanding adsorption capacity of lysozyme (1865 mg/g). Furthermore, the TOCN@macroporous SiO₂ particles have remarkably high reusability (>90% adsorption capacity) and good release of adsorbate (>80%) after 10 times of use. The material proposed in this paper has the potential for application in drug delivery, protein adsorption, biosensors, and other biomedical fields.

Polymeric template assisted synthesis of monodisperse-porous manganese oxide microspheres: a new nanozyme with oxidase-like activity allowing biomolecule determination via bimodal sensing

New template assisted synthesis of monodisperse-porous MnO₂ microspheres and their usage as a nanozyme in the first bimodal sensing of ascorbic acid.

Quantitative assessment of protein adsorption on microparticles with particle mass spectrometry

In this paper, particle mass spectrometry (PMS), which consists of an aerodynamic desorption/ionization (AD) source, a quadrupole ion trap (QIT) mass analyzer, and a charge detector, was exploited to characterize the protein adsorption on microparticles based on the mass variations of microparticles before and after protein adsorption. This method is simple and has low sample cost. Importantly, its mass resolution is good enough to distinguish the microparticles with and without protein. For the adsorption of bovine serum albumin (BSA) on 3 μm porous poly styrene-divinylbenzene (poly S-DVB), the minimum mass increase that can be resolved by PMS corresponds to 128 fg (1.8 ng/cm(2)) or 1.17 × 10(6) BSA molecules on each poly S-DVB particle. With PMS, the adsorption process of BSA on poly S-DVB spheres was successfully characterized, and the obtained maximum adsorption capacity qm and dissociation constant Kd were consistent with that determined by the conventional depletion method. In addition, the influence of surface modification of silica particles on the enzyme immobilization was evaluated. Compared with C4 (propyldimethylsilane), C8 (octyldimethylsilane), and Ph (phenyldimethylchlorosilane), the CN (cyanoethyldimethylchlorosilane) functionalized silica particles were screened to be most beneficial for the immobilization of both lysozyme and trypsin.

Preparation of micrometer-sized, monodisperse "janus" composite polymer particles having temperature-sensitive polymer brushes at half of the surface by seeded atom transfer radical polymerization

Micrometer-sized, monodisperse polystyrene (PS)/poly[methyl methacrylate-(chloromethyl)styrene] [P(MMA-CMS)] composite particles having hemispherical structure were prepared by solvent evaporation from toluene droplets containing dissolved PS and P(MMA-CMS) dispersed in aqueous solution, which had been prepared using the membrane method. The formation of hemispherical ("Janus") morphology by phase separation between the PS and the P(MMA-CMS) was confirmed by both optical and electron microscopy. Atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DM) was subsequently carried out in the presence of hemispherical PS/P(MMA-CMS) composite particles in an aqueous dispersed system. After polymerization, the morphology of the particles changed from spherical to "mushroom" shape as observed by scanning electron microscopy, indicating that DM polymerized inside or on the surface of half [P(MMA-CMS) phase] of the particles. 1H NMR spectra were consistent with chloromethyl functional groups in P(MMA-CMS) operating as ATRP initiators in the DM polymerization.

Synthesis and Characterization of Degradable p(HEMA) Microgels: Use of Acid-Labile Crosslinkers

New divinyl-functionalized acetal-based crosslinkers were synthesized as building elements to form acid-labile microgel particles for controlled-release applications. The synthesized crosslinkers underwent hydrolysis at slightly acidic pHs in less than 1 h while they were stable at neutral pHs for longer times. HEMA was copolymerized with the crosslinkers via an inverse emulsion polymerization technique using a redox initiator system at room temperature to form crosslinked, colloidal p(HEMA) microgels. Microgels in diameters ranging from 150 to 475 nm with narrow distribution could be produced. The crosslinking density and the diameter of the microgels were found to be controlled by monomer/crosslinker feed ratio. The microgels demonstrated a pH-dependent cleavage behavior that mimicked the pH-dependent hydrolysis profile of the acid-labile crosslinkers. Model biomacromolecules, i.e., Rhodamine B-labeled dextran and BSA were efficiently loaded into the microgels. The release of the biomolecules from p(HEMA) microgels was also found to be controllable by the pH of the environment similar to the particle degradation. The protein released from the microgels was observed to retain its structural stability.

Using TEM to couple transient protein distribution and release for PLGA microparticles for potential use as vaccine delivery vehicles

In the development of tunable PLGA microparticles as vaccine delivery vehicles, it is important to understand the drug distribution within the microparticle over time as well as the long-term release of the drug during polymer degradation. This study addresses the transient 3-D drug distribution in PLGA microparticles during in vitro degradation. Specifically, poly (lactide-co-glycolide) (PLGA 75:25) microparticles containing ovalbumin (OVA) as a model protein were fabricated by double-emulsion (w/o/w) method. The microparticles were incubated at 37 degrees C and 250 rpm in PBS buffer (pH 7.4) over a 100-day period. The in vitro polymer erosion, transient protein distribution profiles and protein release behaviors were investigated. Protein release profiles were determined via spectrophotometry using a BCA assay for the solution. Transmission electron microscopy (TEM) images were obtained for the OVA-loaded microparticles before and during degradation (0 day, 30 days and 60 days), and the corresponding 3-D constructions were developed. From the 3-D constructions, the overall protein distribution of the entire microparticle was vividly reflected. Pixel number analysis of the TEM images was used to quantify transient protein distribution. The transient protein release obtained from the TEM analysis was in good agreement with the BCA analysis. This technique provides an additional tool in helping develop polymer matrices for tunable delivery vehicles in vaccination and other drug delivery scenarios.