Bifunctional fluorescent molecularly imprinted resin based on carbon dot for selective detection and enrichment of 2,4-dichlorophenoxyacetic acid in lettuce.

The work provided a method for synthesizing a simple fluorescent molecularly imprinted polymer by surface-initiated atom transfer radical polymerization (SI-ATRP) and its application in real sample. Poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were selected as a matrix, 4-vinylpyridine, ethylene glycol dimethacrylate, 2,4-dichlorophenoxyacetic acid (2,4-D) as functional monomer, cross-linker and template molecule, respectively, to fabricate MAR@MIP with core-shell structure. For comparison, carbon dot (CD) as a fluorescence source was synthesized with o-phenylenediamine and tryptophan as precursors via hydrothermal method and integrated into MIP to acquire MAR@CD-MIP. MAR@CD-NIP was also prepared without adding the template molecule. The adsorption capacity of MAR@CD-MIP reached 104 mg g-1 for 2,4-D, which was higher than that of MAR@MIP (60 mg g-1). However, the adsorption capacity of MAR@CD-NIP was only 13.2 mg g-1. The linear range of fluorescence detection for 2,4-D was 18-72 µmol/L, and the limit of detection (LOD) was 0.35 µmol/L. The fluorescent MAR@CD-MIP was successfully applied in enrichment of lettuce samples. The recoveries of the three spiked concentrations of 2,4-D in lettuce were tested by fluorescence spectrophotometry and ranged in 97.3-101.7 %. Meanwhile, the results were also verified by HPLC. As a result, bi-functional molecularly imprinted resin was successfully fabricated to detect and enrich 2,4-D in real samples, and exhibited good selectivity, sensitivity and great application prospect in food detection.

Tough and strong sustainable thermoplastic elastomers nanocomposite with self-assembly of SI-ATRP modified cellulose nanofibers.

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

Fabrication of molecularly imprinted resin via controlled polymerization applied in the enrichment of bisphenol A for plastic products.

The addition of bisphenol A has been frequently used in industrial manufacturing because it imparts plastic products with characteristics such as transparency, durability, and excellent impact resistance. However, its widespread use raises concerns about potential leakage into the surrounding environment, which poses a significant risk to human health. In this study, molecularly imprinted polymers with specific recognition of bisphenol A were synthesized through surface-initiated atom transfer radical polymerization using poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) as the substrate, bisphenol A as the template molecule, 4-vinylpyridine as the monomer, and ethylene glycol dimethacrylate as the cross-linker. The bisphenol A adsorption capacity was experimentally investigated, and the kinetic analysis of the molecularly imprinted polymers produced an adsorption equilibrium time of 25 min, which is consistent with the pseudo-second-order kinetic model. The results of the static adsorption experiments exhibited consistency with the Langmuir adsorption model, revealing a maximum adsorption capacity of 387.2 µmol/g. The analysis of molecularly imprinted polymers-enriched actual samples using high-performance liquid chromatography demonstrated excellent selectivity for bisphenol A, with a linear range showing 93.4%-99.7% recovery and 1.1%-6.4% relative standard deviation, demonstrating its high potential for practical bisphenol A detection and enrichment applications.

A combination of surface-initiated atom transfer radical polymerization and photo-initiated "thiol-ene" click chemistry: Fabrication of functionalized macroporous adsorption resins for enrichment of glycopeptides.

A hydrophilic adsorbent (Cys@poly(AMA)@MAR) was successfully prepared for the enrichment of N-glycopeptides via surface-initiated atom transfer radical polymerization (SI-ATRP) and photo-initiated "thiol-ene" reaction using monodisperse macroporous adsorbent resin (MAR) as adsorption matrix. Due to the presence of electron-deficient acrylic groups and electron-rich vinyl groups in allyl methacrylate (AMA), both of them can participate in free radical reaction. Therefore, the polymerization time of SI-ATRP was optimized. The resulting poly(AMA)@MAR was modified with l-cysteine (L-Cys) via photo-initiated "thiol-ene" reaction, and the amount of vinyl retained was determined by measuring the adsorption of Cu2+. The Cys@poly(AMA)@MAR pendant brushes with high density of amine and carboxyl groups could capture N-glycopeptides from IgG digest and human serum digest by hydrophilic interaction. The 22 N-glycopeptides were identified from IgG digest and the limit of detection reached 10 fmol. The 319 N-glycosylation sites and 583 N-glycopeptides were identified from 2 µL human serum digest and mapped to 147 glycoproteins. It demonstrates great potential and commercialization prospects for the enrichment of N-glycopeptides.

Colloidal Crystal Films with Narrow Reflection Bands by Hot-Pressing of Polymer-Grafted Silica Particles.

Previous reports have shown that colloidal crystal (CC) films with visible Bragg reflection characteristics can be fabricated by the surface modification of monodisperse silica particles (SiPs) with poly(methyl methacrylate) (PMMA) chains, followed by hot-pressing at 150 °C. However, the reflection bands of the CC films were very broad due to their relative disordering of SiPs. In this report, we attempted to fabricate the CC films using SiPs surface-modified with poly(n-octyl acrylate) (POA) chains by hot-pressing. When the cast films of POA-grafted SiPs were prepared by hot-pressing at 100 °C, the reflection bands were narrow rather than those of CC films of PMMA-grafted SiPs. This can be ascribed to easy disentanglement of POA chains during the hot-pressing process, thereby enabling the formation of well-ordered CC structures. Moreover, the reflection colors of CC films could be easily tuned by controlling the molecular weight of POA chains grafted on the SiP surface.

Surface-Modified Melt Coextruded Nanofibers Enhance Blood Clotting In Vitro.

Blood loss causes an estimated 1.9 million deaths per year globally, making new methods to stop bleeding and promote clot formation immediately following injury paramount. The fabrication of functional hemostatic materials has the potential to save countless lives by limiting bleeding and promoting clot formation following an injury. This work describes the melt manufacturing of poly(ε-caprolactone) nanofibers and their chemical functionalization to produce highly scalable materials with enhanced blood clotting properties. The nanofibers are manufactured using a high throughput melt coextrusion method. Once isolated, the nanofibers are functionalized with polymers that promote blood clotting through surface-initiated atom transfer radical polymerization. The functional nanofibers described herein speed up the coagulation cascade and produce more robust blood clots, allowing for the potential use of these functional nonwoven mats as advanced bandages.

Synthesis of Green and Red-Emitting Polymethyl Methacrylate Composites Grafted from ZnAl2O4:Mn-Bonded GO via Surface-Initiated Atom Transfer Radical Polymerization.

A novel dual green and red-emitting photoluminescent polymer composite ZnAl2O4:Mn-bonded GO/polymethyl methacrylate (PMMA) was synthesized in a single-step reaction by surface-initiated atom transfer radical polymerization (SI-ATRP). The polymer chain was surface-initiated from the ZnAl2O4:Mn/GO, and the final products have a homogenous photoluminescent property from ZnAl2O4:Mn and better mechanical properties strengthened by graphene oxide (GO). The morphologies of ZnAl2O4:Mn/GO and the polymer composites were verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction analysis (XRD) revealed the two valence states of Mn (Mn2+, Mn4+) existing in the ZnAl2O4 host lattice, while Fourier-transform infrared spectroscopy (FTIR) spectra proved the transference of the active group, C-Br, from the initiator to the monomer during the polymerization. Gel permeation chromatography (GPC) shows the narrow dispersity of polymer composites fabricated through SI-ATRP. The SEM and FTIR results show the successful 'graft' of the polymer chains from the surface of ZnAl2O4:Mn/GO. The dual green and red-emitting polymer composites were synthesized, confirmed by the photoluminescence (PL) and photoluminescence excitation (PLE) results.

Fabrication of copolymer brushes grafted superporous agarose gels: Towards the ultimate ideal particles for efficient affinity chromatography.

A composite immobilized-metal affinity agarose particle was designed for the selective separation and purification of histidine-tagged proteins from complicated biological samples. The composite particle was constructed using superporous agarose particles as supporting matrix, flexible copolymer brushes as scaffolds to render higher ligand densities, and Ni2+-chelated iminodiacetic acids as recognition elements. Superporous agarose composite particles endow high permeability and interfering substance tolerance. The copolymer brush was prepared by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide and glycidyl methacrylate, followed by iminodiacetic acids and Ni2+ ions. The physical and chemical properities of the composite particle were thoroughly investigated. The composite particles were shown to be able to selectively separate histidine-tagged recombinant proteins in the presence of high quantities of interfering chemicals in a model protein-binding experiment. By altering the temperature, the protein binding of the composite particles can be modulated. The superporous agarose particles supported polymer brush enables fast and efficient separation and purification of target proteins with high permeability, low backpressure, and high interfering matrix tolerance, which pave the path for bioseparation through designing and fabrication of novel agarose particles-based functional materials.

Infection Resistant Surface Coatings by Polymer Brushes: Strategies to Construct and Applications.

Bacteria-assisted infections on biomaterials used inside a body as an implant/device are one of the major threats to human health. Microbial-resistant coatings on biomaterials can potentially be considered to mitigate the biomaterial-associated infections. Usually biomaterials with leachable antimicrobial coatings, though economically attractive, provide only short-term protection of the surface against bacteria. Therefore, a stable, nonfouling or bactericidal, and biocompatible polymeric coating is highly desirable. In this regard, polymer brushes, defined as polymer chains tethered to a surface by one end, with suitable anti-infective functionality, represent a useful class of stable coatings which are covalently connected to the underlying surface, thus prolonging the infection resistance of the coated surface. Surface-initiated atom transfer radical polymerization (SI-ATRP) is a versatile technique for the generation of polymeric brushes via "grafting from" way. In this review, we have attempted to give a brief overview about the recent developments of surface coatings by infection-resistant polymer brushes synthesized via SI-ATRP and their applications in the biomedical field. On the basis of their charges, these anti-infective brushes can be classified into five different categories such as neutral, cationic, anionic, zwitterionic, and mixed brushes. The working mechanism of each type of brush in repelling (nonfouling/bacteriostatic) and/or killing (bactericidal) the bacteria has also been discussed. A brief summary of their future scope is also highlighted.

Protein Patterning on Microtextured Polymeric Nanobrush Templates Obtained by Nanosecond Fiber Laser.

Micropatterned polymer brushes have attracted attention in several biomedical areas, i.e., tissue engineering, protein microarray, biosensors, etc., for precise arrangement of biomolecules. Herein, a facile and scalable approach is reported to create microtextured polymer brushes with the ability to generate different type of protein patterns. Nanosecond fiber laser is exploited to generate micropatterns on poly(poly(ethylene glycol) methacrylate) (polyPEGMA) brush modified Ti alloy substrate. Surface initiated atom transfer radical polymerization is employed to grow PolyPEGMA brush (11-87 nm thick) on Ti alloy surface immobilized with initiator having an initiator density (σ*) of 1.5 initiators per nm2 . Polymer brushes are then selectively laser ablated and their presence on nontextured area is confirmed by atomic force microscopy, fluorescence microscopy, and X-ray photoelectron spectroscopy. Spatial orientation of biomolecules is first achieved by nonspecific protein adsorption on areas ablated by the laser, via physisorption. Further, patterned brushes of polyPEGMA are modified to activated ester that gives rise to protein conjugation specifically on nonlaser ablated brush areas. Moreover, the laser ablated brush modified patterned template is also successfully utilized for generating alternate patterns of bacteria. This promising technique can be further extended to create interesting patterns of several biomolecules which are of great interest to biomedical research community.

Tailor-made magnetic nanocomposite with pH and thermo-dual responsive copolymer brush for bacterial separation.

Rapid detection of pathogenic bacteria particularly in food samples demands efficient separation and enrichment strategies. Here, hydrophilic temperature-responsive boronate affinity magnetic nanocomposites were established for selective enrichment of bacteria. The thermo-responsive polymer brushes were developed by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide (NIPAm) and allyl glycidyl ether (AGE), followed by a reaction of epoxy groups, and incorporation of fluorophenylboronic acid. The physical and chemical characteristics of the magnetic nanocomposites were analyzed systematically. After optimization, S. aureus and Salmonella spp. showed high binding capacities of 32.14 × 106 CFU/mg and 50.98 × 106 CFU/mg in 0.01 M PBS (pH 7.4) without bacteria death. Bacterial bindings can be controlled by altering temperature and the application of competing monosaccharides. The nanocomposite was then utilized to enrich S. aureus and Salmonella spp. from the spiked tap water, 25% milk, and turbot extraction samples followed by multiplex polymerase chain reaction (mPCR), which resulted in high bacteria enrichment, and demonstrated great potential in separation of bacteria from food samples.

Hybrid "Kill and Release" Antibacterial Cellulose Papers Obtained via Surface-Initiated Atom Transfer Radical Polymerization.

Infectious diseases triggered by bacteria cause a severe risk to human health. To counter this issue, surfaces coated with antibacterial materials have been widely used in daily life to kill these bacteria. The substrates enabled with a hybrid kill and release strategy can be employed not only to kill the bacteria but also to wash them using external stimuli (temperature, pH, etc.). Utilizing this concept, we develop thermoresponsive antibacterial-cellulose papers to exhibit hybrid kill and release properties. Thermoresponsive copolymers [p(NIPAAm-co-AEMA)] are grafted on cellulose papers using a surface-initiated atom transfer radical polymerization approach for bacterial debris release. Later for antibacterial properties, silver nanoparticles (AgNPs) are immobilized on thermoresponsive copolymer-grafted cellulose papers using electrostatic interactions. We confirm the thermoresponsive copolymer grafting and AgNP coating by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Thermoresponsiveness and reusability of the modified cellulose papers are confirmed through water contact angle measurements. The interaction potency between AgNPs and modified cellulose is validated by inductively coupled plasma atomic emission spectroscopy analysis. Gram-negative bacteria Escherichia coli (E. coli DH5-α) is used to demonstrate antibacterial hybrid kill and release performance. Agar-diffusion testing demonstrates the antibacterial nature of the modified cellulose papers. The fluorescence micrograph reveals that modified cellulose papers can effectively release almost all the dead bacterial debris from their surfaces after thermal stimulus wash. The modified cellulose paper surfaces are expected to have wide applications in the field of exploring more antibacterial and smart surfaces.

Infection resistant polymer brush coating on the surface of biodegradable polyester.

Biomaterials with anti-infective coatings are usually found to suffer from low cyto-compatibility and therefore, development of a stable, effective polymeric anti-bacterial substrate without compromising the biocompatibility is still an unmet challenge. Addressing this, a simple strategy for developing non-leaching antibacterial coating on a biodegradable substrate is reported here. The strategy can be utilized for mitigating serious biomedical implant related complications arising from generation of biocide resistant bacterial strains, losing antibacterial activity over time etc. without significantly compromising the cytocompatibility of the biomaterials. To develop the infection resistant yet cytocompatible biomaterials comprised of tartaric acid based biodegradable aliphatic polyester, we have primarily focussed on attaching anti-infective polymer brushes such as poly (2-hydroxyethyl methacrylate) (PHEMA), poly (poly (ethylene glycol) methacrylate) (PPEGMA) and poly[(2-methacryloyloxyethyl] trimethyl ammonium chloride) (PMETA) on hydroxyl functionalized polyester substrate via surface initiated atom transfer radical polymerization (SIATRP). The brushes were thoroughly characterized for reaction kinetics, grafting yield, surface density, topography and hydrophilicity. Among the various brushes, cationic polymer brush (PMETA) was found to exhibit highest antibacterial activity, with only ~3% and ~4% adherence of E. coli (Escherichia coli) and S. aureus (Staphylococcus aureus), respectively. In order to show its widespread use and also to vary initiator density, polylactic acid (PLA) was blended with this tartaric acid based aliphatic polyester and a 3D (three-dimensional) scaffold was fabricated by 3D printing using the blend. Finally, PMETA brush was grown onto the scaffold surface for various time periods and the evaluation of antibacterial activity (using gram positive and gram-negative bacteria) and cytocompatibility (using mammalian osteoblast cells) were carried out on the brush modified scaffold. A balance between antibacterial activity and cytocompatibility was found at optimum brush length achieved after 18 h of SIATRP suggesting that this composition offers a stable, non-leaching, anti-infective, but cytocompatible coating on biodegradable polymeric implant surface for addressing several biomaterials associated infections.

Multi-layer PDMS films having antifouling property for biomedical applications.

Poly(dimethylsiloxane) (PDMS) elastomer is now a well-known material for packaging implantable biomedical micro-devices owing to unique bulk properties such as biocompatibility, low toxicity, excellent rheological properties, good flexibility, and mechanical stability. Despite the desirable bulk characteristics, PDMS is generally regarded as a high-flux material for oxygen and water vapor to penetrate compared with other polymeric barrier materials, which is related to the defect-induced penetration through the packaging coating prepared by the traditional deposition techniques. Besides, its hydrophobic nature causes serious fouling problems and limits the practical application of PDMS-based devices. In this work, the performance of silicone thin films as a packaging layer was improved by the fabrication of the roller-casted multiple thin layers to minimize a defect-induced failure. To confer hydrophilicity and cell fouling resistance, high-density and well-defined poly(oligo(ethylene glycol) methacrylate) (POEGMA) brushes were tethered via the surface-initiated atom transfer radical polymerization (SI-ATRP) technique on the roller-casted multiple thin PDMS layers. The characteristics of fabricated substrates were determined by static water contact angle measurement, X-ray photoelectron spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy. In vitro cell behavior of POEGMA-grafted PDMS substrates was evaluated to examine cell-fouling resistance.

In Situ Surface-Initiated Atom-Transfer Radical Polymerization Utilizing the Nonvolatile Nature of Ionic Liquids: A First Attempt.

In this paper, in situ surface-initiated atom-transfer radical polymerization (SI-ATRP) based on both an open and a coated system, without using volatile reagents, was developed to overcome the limited usage of ATRP due to the necessity of sealing. Nonvolatile ionic liquid (IL)-type components were used, specifically N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide as the polymerizable monomer and N,N-diethylmethyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide as the polymerization solvent. In the experiment, the reversible-deactivation radical polymerization characteristics are properly ensured in nonvolatile ATRP solution coated on silicon wafer as thin liquid film, to form concentrated polymer brushes (CPBs). The average molecular weight and molecular-weight distribution of the polymer produced in the liquid film and formed on silicon wafer were measured by gel permeation chromatography, which confirms that the polymerization reaction occurred as designed. Furthermore, it is clarified that the surface of the polymer brush synthesized in situ swollen by IL also exhibited low friction characteristics, comparable to that synthesized in a typical immersion process. This paper is the first to establish the effectiveness of in situ preparation for CPBs by using the coating technique.

Surface-Initiated Atom Transfer Polymerized Anionic Corona on Gold Nanoparticles for Anti-Cancer Therapy.

Surface initiated atom transfer radical polymerization (SI-ATRP) documented a simple but efficient technique to grow a dense polymer layer on any surface. Gold nanoparticles (AuNPs) give a broad surface to immobilize sulfhyryl group-containing initiators for SI-ATRP; in addition, AuNPs are the major nanoparticulate carriers for delivery of anti-cancer therapeutics, since they are biocompatible and bioinert. In this work, AuNPs with a disulfide initiator were polymerized with sulfoethyl methacrylate by SI-ATRP to decorate the particles with anionic corona, and branched polyethyeleneimine (PEI) and siRNA were sequentially layered onto the anionic corona of AuNP by electrostatic interaction. The in vitro anti-cancer effect confirmed that AuNP with anionic corona showed higher degrees of apoptosis as well as suppression of the oncogene expression in a siRNA dose-dependent manner. The in vivo study of tumor-bearing nude mice revealed that mice treated with c-Myc siRNA-incorporated AuNPs showed dramatically decreased tumor size in comparison to those with free siRNA for 4 weeks. Furthermore, histological examination and gene expression study revealed that the decorated AuNP significantly suppressed c-Myc expression. Thus, we envision that the layer-by-layer assembly on the anionic brushes can be potentially used to incorporate nucleic acids onto metallic particles with high transfection efficiency.

Facile preparation of polymer-brush reverse-phase/hydrophilic interaction/ion-exchange tri-mode chromatographic stationary phases by controlled polymerization of three functional monomers.

Stationary phases with multiple-mode mechanism are beneficial to meet the needs of complex samples, but there are few multiple-mode stationary phases which can adjust the relative strength among multiple-forces imposed on the solutes. This work presents a facile preparation method of reverse-phase/hydrophilic interaction/ion-exchange tri-mode stationary phase, in which three functional monomers, lauryl methacrylate (LMA), hydroxyethyl methylacrylate (HEMA) and dimethylaminoethyl methacrylate (DMAEMA) as co-monomers underwent surface initiated-atom transfer radical polymerization (SI-ATRP) on the surface of silica. The structure of stationary phases was characterized and their chromatographic properties were investigated using various solutes. By comparison with classical single-mode columns, it is found that the newly designed columns can offer multiple interactions including hydrophobic, hydrophilic and electrostatic interactions and show good separation abilities to the tested solutes. Besides, changing the ratios of LMA, HEMA and DMAEMA in SI-ATRP system can easily adjust the relative strength of three interactions imposed on the solutes, inducing adjustable separation selectivity of the columns. The improved separation of multivitamin sample and the successful use of the columns in Per aqueous liquid chromatography indicate the potential of the tri-mode stationary phases.

Polymerization of glycidyl methacrylate from the surface of cellulose nanocrystals for the elaboration of PLA-based nanocomposites.

Cellulose nanocrystals (CNCs) are used to design nanocomposites because of their high aspect ratio and their outstanding mechanical and barrier properties. However, the low compatibility of hydrophilic CNCs with hydrophobic polymers remains a barrier to their use in the nanocomposite field. To improve this compatibility, poly(glycidyl methacrylate) (PGMA) was grafted from CNCs containing α-bromoisobutyryl moieties via surface-initiated atom transfer radical polymerization. The novelty of this research is the use of a reactive epoxy-containing monomer that can serve as a new platform for further modifications or crosslinking. Polymer-grafted CNC-PGMA-Br prepared at different polymerization times were characterized by XRD, DLS, FTIR, XPS and elemental analysis. Approximately 40 % of the polymer at the surface of the CNCs was quantified after only 1 h of polymerization. Finally, nanocomposites prepared with 10 wt% CNC-PGMA-Br as nanofillers in a poly(lactic acid) (PLA) matrix exhibited an improvement in their compatibilization based on SEM observation.

Preparation of high-capacity magnetic polystyrene sulfonate sodium material based on SI-ATRP method and its adsorption property research for sulfonamide antibiotics.

A novel polystyrene sulfonate sodium (PSS) magnetic material was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). The starting materials were brominated magnetic material as the carrier and macroinitiator, sodium styrene sulfonate (NaSS) as the monomer, and cuprous bromide/2,2'-dipyridyl as the catalyst system. The PSS material was characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, transmission electron microscope (TEM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and a vibrating sample magnetometer (VSM). The adsorption properties of the material were then investigated on sulfa antibiotics. The kinetic and thermodynamic parameters were determined in adsorption of sulfamethazine (the smallest molecular-weight sulfonamide). The adsorption amount of sulfamerazine free acid (SMR) was found to increase with the initial concentration and temperature of SMR in solution. The adsorption effect was maximized at an initial concentration of 0.6 mmol/L. The static saturation adsorption capacity of the material was 33.53 mg/g, Langmuir and Freundlich equations exhibited good fit. The thermodynamic equilibrium equation is calculated as ΔG < 0, ΔH = 38.29 kJ/mol, ΔS > 0, which proves that the adsorption process is a process of spontaneous, endothermic and entropy increase. Kinetic studies show that the quasi-second-order kinetic equation can better fit the kinetic experimental results, which is consistent with the quasi-second-order kinetic model. The experimental results of kinetic studies were well fitted to a quasi-second-order kinetic equation. High performance liquid chromatography (HPLC) of an actual milk sample treated by the PSS magnetic material confirmed the strong adsorption of SMR from milk.

Hybrid Mesoporous Silica Nanoparticles Grafted with 2-(tert-butylamino)ethyl Methacrylate-b-poly(ethylene Glycol) Methyl Ether Methacrylate Diblock Brushes as Drug Nanocarrier.

This paper introduces the synthesis of well-defined 2-(tert-butylamino)ethyl methacrylate-b-poly(ethylene glycol) methyl ether methacrylate diblock copolymer, which has been grafted onto mesoporous silica nanoparticles (PTBAEMA-b-PEGMEMA-MSNs) via atom transfer radical polymerization (ATRP). The ATRP initiators were first attached to the MSN surfaces, followed by the ATRP of 2-(tert-butylamino)ethyl methacrylate (PTBAEMA). CuBr2/bipy and ascorbic acid were employed as the catalyst and reducing agent, respectively, to grow a second polymer, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). The surface structures of these fabricated nanomaterials were then analyzed using Fourier Transform Infrared (FTIR) spectroscopy. The results of Thermogravimetric Analysis (TGA) show that ATRP could provide a high surface grafting density for polymers. Dynamic Light Scattering (DLS) was conducted to investigate the pH-responsive behavior of the diblock copolymer chains on the nanoparticle surface. In addition, multifunctional pH-sensitive PTBAEMA-b-PEGMEMA-MSNs were loaded with doxycycline (Doxy) to study their capacities and long-circulation time.