Surface-initiated Atom Transfer Radical Polymerization Research Articles

Artificial Zymogen Based on Protein-Polymer Hybrids.

This study explores the synthesis and application of artificial zymogens using protein-polymer hybrids to mimic the controlled enzyme activation observed in natural zymogens. Pro-trypsin (pro-TR) and pro-chymotrypsin (pro-CT) hybrids were engineered by modifying the surfaces of trypsin (TR) and chymotrypsin (CT) with cleavable peptide inhibitors utilizing surface-initiated atom transfer radical polymerization. These hybrids exhibited 70 and 90% reductions in catalytic efficiency for pro-TR and pro-CT, respectively, due to the inhibitory effect of the grafted peptide inhibitors. The activation of pro-TR by CT and pro-CT by TR resulted in 1.5- and 2.5-fold increases in enzymatic activity, respectively. Furthermore, the activated hybrids triggered an enzyme activation cascade, enabling amplification of activity through a dual pro-protease hybrid system. This study highlights the potential of artificial zymogens for therapeutic interventions and biodetection platforms by harnessing enzyme activation cascades for precise control of catalytic activity.

Fine carbonyl iron particles grafted with poly(2-isopropenyl-2-oxazoline): A potential embolization agent for cancer therapy

Despite the significant success of clinical trials on cancer patients using the therapy with carbonyl iron (CI) particles, this topic laid dormant for over two decades. In this context, we developed a CI particle-based embolization agent via polymer surface engineering and tested its biocompatibility and behavior in contact with human blood. The finest grade of the CI particles was controllably grafted with poly(2-isopropenyl-2-oxazoline) (PiPOx) using surface-initiated atom transfer radical polymerization (ATRP) to achieve a system combining the properties of suitable size, high magnetization, and advantages at the cellular level connected to the presence of PiPOx. The cell viability of 3T3 fibroblasts and P388.D1 macrophages was investigated after treatment with particle extracts and was found to be concentration-dependent but generally demonstrated no or mild cytotoxicity. The PiPOx-grafted particles showed negligible effect on the breakdown of human erythrocytes and significantly improved hydrophilic-hemophilic properties when compared to bare CI. The magnetorheological (MR) activity of the particles dispersed in human blood was studied in vitro under shear mode conditions showing slightly decreased shear stresses but improved sedimentation stability. Moreover, the effect of PiPOx molecular weight on the studied parameters was monitored across the whole range of tests. The study demonstrates the potential of prepared core-shell structures in biomedical and related fields of application.

Illuminating Biomimetic Nanochannels: Unveiling Macroscopic Anticounterfeiting and Photoswitchable Ion Conductivity via Polymer Tailoring.

Artificial photomodulated channels represent a significant advancement toward practical photogated systems because of their remote noncontact stimulation. Ion transport behaviors in artificial photomodulated channels, however, still require further investigation, especially in multiple nanochannels that closely resemble biological structures. Herein, we present the design and development of photoswitchable ion nanochannels inspired by natural channelrhodopsins (ChRs), utilizing photoresponsive polymers grafted anodic aluminum oxide (AAO) membranes. Our approach integrates spiropyran (SP) as photoresponsive molecules into nanochannels through surface-initiated atom transfer radical polymerization (SI-ATRP), creating a responsive system that modulates ionic conductivity and hydrophilicity in response to light stimuli. A key design feature is the reversible ring-opening photoisomerization of spiropyran groups under UV irradiation. This transformation, observable at the molecular level and macroscopically, allows the surface inside the nanochannels to switch between hydrophobic and hydrophilic states, thus efficiently modulating ion transport via changing water wetting behaviors. The patternable and erasable polySP-grafted AAO, based on a controllable and reversible photochromic effect, also shows potential applications in anticounterfeiting. This study pioneers achieving macroscopic anticounterfeiting and photoinduced photoswitching through reversible surface chemistry and expands the application of polymer-grafted structures in multiple nanochannels.

Adsorption and detection of praseodymium ion by ion-imprinted polymer with ultra-low sensitivity.

A novel kind of carbon dot (CD) was prepared by one-step hydrothermal microwave assisted method using L-tryptophan and L-tartaric acid as raw materials. Monodisperse poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were utilized as the matrix, with praseodymium (Pr) ion (Pr3+) as the template, methacrylic acid as the functional monomer, and 5-amino-8-hydroxyquinoline (5-AHQ) acts as the ligand. A composite microsphere of ion-imprinted polymer (IIP) and CD (noted CD@IIP) was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). For comparison, IIP without CD (Pr-IIP) and non-imprinted polymer (NIP) were also prepared. Through static adsorption experiments, it was determined that the saturated adsorption amount of CD@IIP is 47.19mgg-1, that of Pr-IIP is 54.49mgg-1, while that of NIP is only 24.32mgg-1. Dynamic adsorption experiments showed that the equilibrium of three kinds of materials wasreached within 30min. Particularly, CD@IIP could emit two fluorescence peaks at 325nm and 421nm under ultraviolet irradiation, and exhibited excellent selectivity and fluorescence quenching effect on Pr3+. The fluorescence response of Pr3+ in the range 0-400μmol L-1 was determined by ratiometric fluorescence method, offering a two-stage model and robust linear regression coefficient. These results demonstrated that CD@IIP exhibited selective adsorption ability for Pr3+, and a sensitive, rapid and simple method for detection of Pr3+ was successfully developed.

Design and fabrication of acorn-like Janus molecularly imprinted materials for highly specific separation and enrichment of oxytetracycline from restaurant oily wastewater

Molecularly imprinted polymer (MIP) is dedicated to the adsorption of target substances in the aqueous phase, but ignores the adsorption in a more complex environment (oily wastewater). In order to explore the application field of existing MIPs, acorn-like Janus particles were fabricated by photo-initiated seed swelling polymerization. A novel amphiphilic Janus-MIP was prepared with the acorn-like Janus particles as matrix, methacrylic acid, ethylene dimethacrylate and oxytetracycline (OTC) as functional monomers, crosslinking agents and template molecules via surface initiated-atom transfer radical polymerization (SI-ATRP). For comparison, the poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly (GMA-co-EDMA)) microspheres were also utilized as the matrix to prepare common spherical-MIP. The adsorption capacity of Janus-MIP for OTC was 23.8 mg g−1 in oil-water system, while the adsorption capacity of spherical-MIP for OTC was only 12.6 mg g−1 in the same system. At the same time, through high performance liquid chromatography (HPLC) analysis, Janus-MIP can specifically recognize and adsorb trace OTC in restaurant oily wastewater samples, and the proposed method exhibited a lower limit of detection (LOD, 3 ng mL−1) and a higher OTC recovery rate (94.2 %–98.4 %). This work demonstrated great potential for the detection and control of OTC contamination from real samples in an oil-water mixed environment.

Poly(N‐2‐Aminoethylacrylamide)‐Cu(I) Chelate Grafted from Fe3O4@SiO2 Core‐Shells for the Selective Monoarylation of Anilines via the Ullmann Reaction

AbstractThe present work describes the grafting of a polymer‐metal chelate (PMC) from Fe3O4@SiO2 core‐shells via the Surface Initiated‐Atom Transfer Radical Polymerization (SI‐ATRP). The magnetic core‐shells were silylated by 2‐bromo‐2‐methyl‐N‐(3‐(trimethoxysilyl)propanamide (BTPAm) to give the surface‐anchored ATRP initiator. Acrylamide was polymerized from the Fe3O4@SiO2 surface via the ATRP approach. The grafted magnetic nanoparticles were trans‐amidated with ethylenediamine to give poly(N‐2‐aminoethylacrylamide) grafted magnetic core‐shells, Fe3O4@SiO2‐g‐PAE‐AAm. The grafted chelating polymer ligand (CPL) was treated with an acetonitrile solution of CuI to afford the Fe3O4@SiO2‐g‐PAE‐AAm−Cu(I). The grafted PMC was characterized by FT‐IR, CP/MAS 13C NMR, and thermo‐gravimetric analysis (TGA). The grafted PMC catalyzed the N−C bond formation via the Ullmann‐type N‐arylation reaction of haloarenes and anilines under optimal reaction conditions. Mono N‐arylation product was obtained as the major product with excellent selectivity. The excellent recyclability of the catalyst was shown by negligible deactivation over six runs.

Improvement of tribological and anti-corrosive performance of MXene nanosheets by grafting polymer brush

Herein, the anti-corrosive polymer brush functionalized MXene (P-MBTS2MA@MXene) was successfully prepared via surface-initiated polymerization. First, the dopamine initiator (DA-Br) can self-assemble onto MXene nanosheets formation of initiator modified MXene (PDA-Br@MXene) via spontaneous oxidative polymerization, then the corrosion inhibitor MBT derivative MBTS2MA monomer was grafted onto MXene nanosheets through surface-initiated atom transfer radical polymerization (SI-ATRP) to obtain polymer brush P-MBTS2MA functionalized MXene (P-MBTS2MA@MXene). The prepared P-MBTS2MA@MXene served as lubricant additive, manifesting good tribological properties with a low COF of 0.098 % and 94.8 % wear-reduction, which is attributed to the shielding effect and protective film formed by P-MBTS2MA@MXene. Additionally, the grafting P-MBTS2MA endows MXene nanosheets with improved anti-corrosion property, which prevents further corrosion of the metal surface via releasing corrosion resistance molecule MBT.

Efficient synthesis of the undiluted vegetable juice-compatible hydrophilic quantum dot-labeled fluorescent molecularly imprinted polymer microspheres via facile one-pot surface-initiated ARGET ATRP

The development of fluorescent molecularly imprinted polymers (MIPs) applicable for herbicide optosensing in the undiluted vegetable juices is highly important for food safety control, but still remains a challenging task. Herein, we report on a facile and efficient new strategy for the synthesis of hydrophilic quantum dot (QD)-labeled fluorescent MIP microspheres capable of directly and selectively optosensing a widely used herbicide (i.e., 2,4-dichlorophenoxyacetic acid, 2,4-D) in the undiluted vegetable juices. Such fluorescent MIP particles were readily prepared through one-step grafting of a red CdTe QD-labeled 2,4-D-MIP layer with hydrophilic polyethylene glycol brushes onto the preformed uniform “living” polymer microspheres (with surface-bound alkyl halide groups) via one-pot surface-initiated activator regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) (SI-ARGET ATRP). They proved to be a highly useful optosensor with high 2,4-D selectivity and sensitivity (the limit of detection ≤ 0.14 μM) in the undiluted Chinese cabbage and cucumber juices. They also showed excellent photostability and reusability and could be directly utilized for 2,4-D detection with high recoveries (98.2 %-102.4 %) and accuracy (RSD≤3.8 %) in the undiluted Chinese cabbage and cucumber juices at three spiking levels of both 2,4-D and its mixtures with several analogues. The use of SI-ARGET ATRP significantly reduced the applied copper catalyst concentration (about 5 μM), which greatly alleviated the quenching effect of the copper catalyst on the fluorescence of the QD-labeled MIP (usually observed for those prepared via normal ATRPs that typically use several hundreds of μM of copper catalysts), thus making this facile new strategy highly efficient for developing advanced fluorescent MIPs that hold much promise in various bioanalytical and diagnostic applications.

Individual cell modification with cell surface specific atom transfer radical polymerization for enhanced Cr(VI) removal

Modifying cells with polymers on the surface can enable them to gain or enhance function with various applications, wherein the atom transfer radical polymerization (ATRP) has garnered significant potential due to its biocompatibility. However, specifically initiating ATRP from the cell surface for in-situ modification remains challenging. This study established a bacterial surface-initiated ATRP method and further applied it for enhanced Cr(VI) removal. The cell surface specificity was facilely achieved by cell surface labelling with azide substrates, following alkynyl ATRP initiator specifically anchoring with azide-alkyne click chemistry. Then, the ATRP polymerization was initiated from the cell surface, and different polymers were successfully applied to in-situ modification. Further analysis revealed that the modification of Shewanella oneidensis with poly (4-vinyl pyridine) and sodium polymethacrylate improved the heavy metal tolerance and enhanced the Cr(VI) removal rate of 2.6 times from 0.088h-1 to 0.314h-1. This work provided a novel idea for bacterial surface modification and would extend the application of ATRP in bioremediation.

Investigation of thermodynamically induced nanoparticle localization in Poly(vinylidene fluoride)/Poly(lactic acid) blends with surface-grafted carbon nanotubes

Physically anchoring multi-walled carbon nanotubes (MWCNT) onto the polymer blend interface has been extensively investigated, however, the tunable localization of polymer grafted MWCNT in immiscible polymer blends is seldom reported. Herein, poly(methyl methacrylate) (PMMA) grafted MWCNT (PMMA-g-MWCNT) were nondestructively prepared via the surface-initiated atom transfer radical polymerization. The compatibilization effects of PMMA-g-MWCNT on morphology and mechanical properties of blend composites are investigated. The results demonstrate that the fillers are distributed at the blend interface due to the high affinity between PMMA and PVDF. The interaction between PMMA and PLA changes the crystallinity of blends. Moreover, the surface modification of MWCNT enhances the interaction of filler and matrix, and the elongation at break is as high as 52 % for composites with 10 % PMMA-g-MWCNT. The fracture surface of specimen after tensile tests exhibits an obvious ductile transition with filler contents. This work systematically discussed the relationship between the PMMA-g-MWCNT distribution and the mechanical strength of composites, which provided a solid experimental foundation on the toughening mechanism of PMMA-g-MWCNT used as a compatibilizer for PVDF/PLA blends.

Block copolymer brushes modified cotton fabric for antifouling oil-water separation materials with thermal responsiveness

Polymer brushes have proven to have great potential in oil-water separation but it remains a long-standing challenge to improve their operational stability and service endurance. In this work, we sequentially grafted polydimethylsiloxane (PDMS) and poly (N-isopropylacrylamide) (PNIPAM) brushes on the cotton fabric to prepare a durable and self-reparing oil-water separation film (Co@PDMS/PNIPAM). The grafting of liquid PDMS brushes significantly improved the antifouling performance through its lubricating effect thereby improving the durability. The hydrophilic and thermoresponsive PNIPAM was synthesized through a surface-initiated atom transfer radical polymerization (SI-ARGET ATRP). Co@PDMS/PNIPAM shows high flux in various oily water and bio-solution. More remarkably, Co@PDMS/PNIPAM exhibited intelligent self-repairing characteristics, and this further enhances its stability and service endurance in the application of oil-water separation. The results provide pathways to the preparation of antifouling and durable membranes in the application of water treatment, and resource recovery.

Mechanically Stable and Biocompatible Polymer Brush Coated Dental Materials with Lubricious and Antifouling Properties.

Surface modification plays a crucial role in enhancing the functionality of implanted interventional medical devices, offering added advantages to patients, particularly in terms of lubrication and prevention of undesired adsorption of biomolecules and microorganisms, such as proteins and bacteria, on the material surfaces. Utilizing polymer brushes for surface modification is currently a promising approach to maintaining the inherent properties of materials while introducing new functionalities to surfaces. Here, surface-initiated atom transfer radical polymerization (SI-ATRP) technology to effectively graft anionic, cationic, and neutral polymer brushes from a mixed silane initiating layer is employed. The presence of a polymer brush layer significantly enhances the lubrication performance of the substrates and ensures a consistently low coefficient of friction over thousands of friction cycles in aqueous environments. The antimicrobial efficacy of polymer brushes is evaluated against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli). It is observed that polym er brushes grafted to diverse substrate surfaces displays notable antibacterial properties, effectively inhibiting bacterial attachment. Furthermore, the polymer brush layer shows favorable biocompatibility and anti-inflammatory characteristics, which shows potential applications in dental materials, and other fields such as catheters and foodpackaging.

Detection and adsorption of florfenicol in milk using bifunctional carbon dot-doped molecularly imprinted polymers.

Detection of florfenicol (FF) residues in animal-derived foods, as one of the most widely used antibiotics, is critically important to food safety. The fluorescent molecularly imprinted polymer (MIP) was synthesized by surface-initiated atom transfer radical polymerization technique with poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres, 4-vinylpyridine, ethylene glycol dimethacrylate, and FF as the matrix, functional monomer, crosslinker, and template molecule, respectively. Meanwhile, N-S co-doped carbon dot (CD) was synthesized with triammonium citrate and thiourea as precursors under microwave irradiation at 400W for 2.5min and then integrated into FF-MIP to obtain CD@FF-MIP. For comparison, non-imprinted polymer (NIP) without FF was also prepared. The adsorption capacity of CD@FF-MIP to FF reached 53.1mgg-1, which was higher than that of FF-MIP (34.7mgg-1), whereas the adsorption capacity of NIP was only 17.3mgg-1. The adsorption equilibrium of three materials was reached within 50min. Particularly, CD@FF-MIP exhibited an excellent fluorescence quenching response to FF in the concentration range of 3-50 µmolL-1. As a result, CD@FF-MIP was successfully utilized to extract FF in milk samples, which were analyzed by high-performance liquid chromatography. The standard recoveries were 95.8%-98.2%, and the relative standard deviation was 1.6%-4.2%. The method showed the advantages of simple operation, high sensitivity, excellent selectivity, and low cost, and also demonstrated a great application prospect in food detection.

Surface-Grafted Biocompatible Polymer Conductors for Stable and Compliant Electrodes for Brain Interfaces.

Durable and conductive interfaces that enable chronic and high-resolution recording of neural activity are essential for understanding and treating neurodegenerative disorders. These chronic implants require long-term stability and small contact areas. Consequently, they are often coated with a blend of conductive polymers and are crosslinked to enhance durability despite the potentially deleterious effect of crosslinking on the mechanical and electrical properties. Here the grafting of the poly(3,4 ethylenedioxythiophene) scaffold, poly(styrenesulfonate)-b-poly(poly(ethylene glycol) methyl ether methacrylate block copolymer brush to gold, in a controlled and tunable manner, by surface-initiated atom-transfer radical polymerization (SI-ATRP) is described. This "block-brush" provides high volumetric capacitance (120 F cm─3), strong adhesion to the metal (4h ultrasonication), improved surface hydrophilicity, and stability against 10000 charge-discharge voltage sweeps on a multiarray neural electrode. In addition, the block-brush film showed 33% improved stability against current pulsing. This approach can open numerous avenues for exploring specialized polymer brushes for bioelectronics research and application.

Hydrogen bonds-based flexible regulation of acetaminophen adsorption/desorption behavior in aqueous system: Role of the smart thermoresponsive graphene oxide

Adsorption and regeneration techniques are crucial for the treatment of pharmaceuticals in drinking water. However, adsorbents with strong adsorption binding force and simple regeneration have been a challenging issue in the adsorption area that has not been successfully resolved. In this study, a thermos-responsive smart adsorbent, poly (N-isopropylacrylamide) modified graphene oxide (GO-g-PNIPAM) was successfully synthesized using a “graft from” surface-initiated atom-transfer radical polymerization (Si-ATRP) technology. Acetaminophen (Acet) has an excellent efficient adsorption/desorption behavior (107.40/83.9 mg/g) that is potentially flexible controlled by the modified adsorbent only by adjusting the temperature. This exceptional property is primarily caused by the phenomenon that PNIPAM cooperated with GO to undergo hydrophilic transformation in response to temperature changes, allowing for the free construction and deconstruction of hydrogen bonds between PNIPAM and contaminants. More importantly, as external factors (NaCl and urea) are mediated, the development of hydrogen bonds would be further encouraged to further stabilized the efficiency, and the desorption temperature would continue decrease by 2 and 6 °C, respectively, to promote the regeneration process. This outstanding work provides novel perspectives for subsequent smart sensitive materials to flexibly regulate the treatment efficiency of pollutants.

Sequential assembly enhanced selectivity on magnetic imprinted polymers for specific capture of naringin: A combination of synergistic dual sites and imprinted effect

Green and sustainable recovery of high-value natural flavonoids in agricultural wastes could not only improve natural resource utilization, but also could effectively reduce environmental pollution. Recently, great efforts have been made for research on the development of magnetic imprinted composite adsorbent, but the simultaneous promotion of stable selectivity and high adsorption amounts still faces its challenges. Inspired by “Sandwich-like” transport channels with proper steric and specific affinity sites, herein we designed a new kind of surface-imprinted magnetic colloidal nanocrystal clusters (MCNCs) with dual recognition sites (MCNCs@DR-MIPs) via sequential surface imprinted strategy. A two-step sequential surface-initiated atom transfer radical polymerization (SI-ATRP) was employed to construct the double imprinted sites, which can significantly improve the adsorption selectivity and adsorption amounts. In this design, the metal ion Zn(II) and the low pKa boronic acid APBA (1-allylpyridine-3-boronic acid, pKa = 7.4) could effectively tune the appropriate yolk-shell confinement sites, the obtained artificial double imprinted binding sites establishes the promising chemical environment for selective separation. As expected, the adsorption equilibrium experiments exhibited adsorption kinetics (180 min) and the maximum equilibrium binding capacity (34.60 µmol g−1). In virtue of unique advantages of magnetic separation materials, this novel absorbent exhibited a green and environmentally friendly enrichment process for naringin (NRG). Meanwhile, MCNCs@DR-MIPs showed excellent selectivity (imprinted factor 2.15) and regeneration properties (only decreased by 8.22 % after 7 cycles) for NRG. Additionally, the commercially available NRG could be effectively extracted and concentrated to 94.78 %. This study offers a sustainable effective strategy for flavonoids purification of magnetic separation materials and promotes advance the other natural compounds from agricultural wastes.

Organic nanoparticles with tunable size and rigidity by hyperbranching and cross-linking using microemulsion ATRP

Unlike inorganic nanoparticles, organic nanoparticles (oNPs) offer the advantage of "interior tailorability," thereby enabling the controlled variation of physicochemical characteristics and functionalities, for example, by incorporation of diverse functional small molecules. In this study, a unique inimer-based microemulsion approach is presented to realize oNPs with enhanced control of chemical and mechanical properties by deliberate variation of the degree of hyperbranching or cross-linking. The use of anionic cosurfactants led to oNPs with superior uniformity. Benefitting from the high initiator concentration from inimer and preserved chain-end functionality during atom transfer radical polymerization (ATRP), the capability of oNPs as a multifunctional macroinitiator for the subsequent surface-initiated ATRP was demonstrated. This facilitated the synthesis of densely tethered poly(methyl methacrylate) brush oNPs. Detailed analysis revealed that exceptionally high grafting densities (~1 nm-2) were attributable to multilayer surface grafting from oNPs due to the hyperbranched macromolecular architecture. The ability to control functional attributes along with elastic properties renders this "bottom-up" synthetic strategy of macroinitiator-type oNPs a unique platform for realizing functional materials with a broad spectrum of applications.

Durable and dense zwitterionic polymer brushes initiated from surface-segregated cyclic initiator via atom transfer radical polymerization

Immobilization of initiators on a polymer surface for surface-initiated polymerization has primarily been achieved via covalent bonds. However, this approach is subject to limitations, such as the requirement for additional processing steps and different customized methods tailored to the specific characteristics of each polymer. In this study, initiator immobilization was achieved by surface segregation, a phenomenon observed in polymer blends wherein one component spontaneously enriches the surface, thereby enabling the modification of surface properties. Specifically, we designed cyclic oligomers containing an atom transfer radical polymerization (ATRP) initiator. The enhanced performance of surface segregation mediated by the cyclic topology was evaluated, along with the surface-initiated polymerization initiated by the surface-segregated oligomer. The kinetics of the ATRP reaction for the cyclic initiators were investigated, and the zwitterion polymer brush density was also calculated. The robustness of the brushes was evaluated through leaching tests, which revealed no notable alterations before and after the assessments. The antifouling effect of the brushes was confirmed through protein adsorption, platelet adhesion, bacterial attachment, and whole-blood circulation experiments. These antifouling examinations demonstrated reduced substance attachment of zwitterionic polymer brushes. Lastly, experiments on optimizing the ATRP catalyst loading during the surface-initiated ATRP were conducted. The excellent performance of the cyclic initiators is expected to provide new insights and opportunities in the field of surface-initiated polymerization. Moreover, the formation of zwitterion brushes via cyclic initiators holds promise for versatile applications in the field of long-term utilization in biointerfaces, offering a wide range of potential uses.

Cryogel with Modular and Clickable Building Blocks: Toward the Ultimate Ideal Macroporous Medium for Bacterial Separation.

The lack of practical platforms for bacterial separation remains a hindrance to the detection of bacteria in complex samples. Herein, a composite cryogel was synthesized by using clickable building blocks and boronic acid for bacterial separation. Macroporous cryogels were synthesized by cryo-gelation polymerization using 2-hydroxyethyl methacrylate and allyl glycidyl ether. The interconnected macroporous architecture enabled high interfering substance tolerance. Nanohybrid nanoparticles were prepared via surface-initiated atom transfer radical polymerization and immobilized onto cryogel by click reaction. Alkyne-tagged boronic acid was conjugated to the composite for specific bacteria binding. The physical and chemical characteristics of the composite cryogel were analyzed systematically. Benefitting from the synergistic, multiple binding sites provided by the silica-assisted polymer, the composite cryogel exhibited excellent affinity toward S. aureus and Salmonella spp. with capacities of 91.6 × 107 CFU/g and 241.3 × 107 CFU/g in 0.01 M PBS (pH 8.0), respectively. Bacterial binding can be tuned by variations in pH and temperature and the addition of monosaccharides. The composite was employed to separate S. aureus and Salmonella spp. from spiked tap water, 40% cow milk, and sea cucumber enzymatic hydrolysate, which resulted in high bacteria separation and demonstrated remarkable potential in bacteria separation from food samples.

XPS Depth-Profiling Studies of Chlorophyll Binding to Poly(cysteine methacrylate) Scaffolds in Pigment-Polymer Antenna Complexes Using a Gas Cluster Ion Source.

X-ray photoelectron spectroscopy (XPS) depth-profiling with an argon gas cluster ion source (GCIS) was used to characterize the spatial distribution of chlorophyll a (Chl) within a poly(cysteine methacrylate) (PCysMA) brush grown by surface-initiated atom-transfer radical polymerization (ATRP) from a planar surface. The organization of Chl is controlled by adjusting the brush grafting density and polymerization time. For dense brushes, the C, N, S elemental composition remains constant throughout the 36 nm brush layer until the underlying gold substrate is approached. However, for either reduced density brushes (mean thickness ∼20 nm) or mushrooms grown with reduced grafting densities (mean thickness 6-9 nm), elemental intensities decrease continuously throughout the brush layer, because photoelectrons are less strongly attenuated for such systems. For all brushes, the fraction of positively charged nitrogen atoms (N+/N0) decreases with increasing depth. Chl binding causes a marked reduction in N+/N0 within the brushes and produces a new feature at 398.1 eV in the N1s core-line spectrum assigned to tetrapyrrole ring nitrogen atoms coordinated to Zn2+. For all grafting densities, the N/S atomic ratio remains approximately constant as a function of brush depth, which indicates a uniform distribution of Chl throughout the brush layer. However, a larger fraction of repeat units bound to Chl is observed at lower grafting densities, reflecting a progressive reduction in steric congestion that enables more uniform distribution of the bulky Chl units throughout the brush layer. In summary, XPS depth-profiling using a GCIS is a powerful tool for characterization of these complex materials.