Minjia Meng

Synthesis of hydrophilic surface ion-imprinted polymer based on graphene oxide for removal of strontium from aqueous solution

A novel hydrophilic ion-imprinted polymer based on graphene oxide has been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization with surface imprinting technique. Methylacrylic acid is used as a hydrophilic functional monomer. The resultant adsorbent is verified by UV-vis scanning spectrophotometer, Fourier transmission infrared spectrometry, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, water contact angle measurements, and thermogravimetric analysis. The results suggest that the surface imprinted polymer synthesized by RAFT is a homogeneous thin layer. Owing to the intrinsic advantages of controlling/living polymerization and surface imprinting technology, the obtained RAFT surface ion-imprinted polymer (RAFT-IIP) exhibits excellent imprinting efficiency and adsorption capacity in comparison to the ion-imprinted polymer prepared by traditional radical polymerization. Furthermore, the adsorption isotherm and recognizing ability towards Sr(II) onto RAFT-IIP and non-imprinted polymer (NIP) are compared in batch experiments. The equilibrium data are well fitted by Langmuir model and RAFT-IIP has higher selectivity and nearly four times larger Langmuir calculated maximum adsorption capacity (145.77 mg g−1) than that of NIP at 25 °C. Meanwhile, RAFT-IIP is regenerated and found to be suitable for reuse in successive adsorption–desorption cycles five times without significant loss in adsorption capacity.

Accelerating the design of multi-component nanocomposite imprinted membranes by integrating a versatile metal–organic methodology with a mussel-inspired secondary reaction platform

Efforts to engineer novel membrane materials with enhanced anti-fouling and comprehensive properties as well as highly selective separation abilities are hampered by the lack of effective imprinted cavities and structure stability. In this work, a novel multi-component metal–organic nanocomposite imprinted membrane (MMO-MIM) has been prepared by integrating a bioinspired metal–organic methodology with the secondary surface sol–gel imprinting technique. The synthesis pathway of MMO-MIM involves two steps: initially, a self-polymerized polydopamine process followed by hydrolysis with ammonium fluotitanate on the surface of the PVDF membrane, a surface-initiated sol–gel imprinted procedure is then conducted on the obtained bio-adhesive nano-sized TiO2 surface system for the fabrication of MMO-MIM. Attributed to the formation of the multilayered membrane structure, stronger fouling resistance and largely enhanced adsorption capacities have been obtained in this case. Meanwhile, the as-prepared MMO-MIM not only exhibits rapid adsorption dynamics, but also possesses excellent separation performance (βMMO-MIM/MMO-NIM and βm-cresol/2,4-DP are higher than 2.6 and 4.0, respectively) of templates. In addition, all synthesis procedures were conducted in aqueous or ethanol solution at ambient temperature, which was environmental friendly for scaling up without causing pollution.

An ion-imprinted functionalized SBA-15 adsorbent synthesized by surface imprinting technique via reversible addition–fragmentation chain transfer polymerization for selective removal of Ce(III) from aqueous solution

A novel Ce(III) ion-imprinted polymer (Ce(III)-IIP) has been prepared by surface imprinting technique with reversible addition-fragmentation chain transfer (RAFT) polymerization based on support matrix of SBA-15. The prepared adsorbent is characterized by FT-IR, XRD, SEM, TEM, nitrogen adsorption-desorption, GPC, and TGA. The results suggest that the surface imprinted polymer synthesized by RAFT is a thin layer. For adsorption experiments, Ce(III)-IIP is investigated to remove Ce(III) by column study at different flow rates, initial metal ion concentrations, and adsorption temperature. The dynamic kinetics analyses reveal that the overall adsorption process is successfully fitted with the pseudo-first-order kinetic model and the equilibrium time was 60 min. Meanwhile, the experimental data is in good agreement with Thomas model. Ce(III)-IIP has the excellent selectivity and regenerate property. Meanwhile, the proposed method has been successfully applied in the removal of Ce(III) in natural water samples with satisfactory results. All the results suggest that Ce(III)-IIP could be used as an excellent adsorbent for efficient removal of Ce(III) from aqueous solution.

A Hierarchical Porous Bowl-like PLA@MSNs-COOH Composite for pH-Dominated Long-Term Controlled Release of Doxorubicin and Integrated Nanoparticle for Potential Second Treatment

We chemically integrated mesoporous silica nanoparticles (MSNs) and macroporous bowl-like polylactic acid (pBPLA) matrix, for noninvasive electrostatic loading and long-term controlled doxorubicin (DOX) release, to prepare a hierarchical porous bowl-like pBPLA@MSNs-COOH composite with a nonspherical and hierarchical porous structure. Strong electrostatic interaction with DOX rendered excellent encapsulation efficiency (up to 90.14%) to the composite. DOX release showed pH-dominated drug release kinetics; thus, maintaining a weak acidic pH (e.g., 5.0) triggered sustained release, suggesting the composites great potential for long-term therapeutic approaches. In-vitro cell viability assays further confirmed that the composite was biocompatible and that the loaded drugs were pharmacologically active, exhibiting dosage-dependent cytotoxicity. Additionally, a wound-healing assay revealed the composites intrinsic ability to inhibit cell migration. Moreover, pH- and time-dependent leaching of the integrated MSNs due to pBPLA matrix degradation allow us to infer that the leached (and drug loaded) MSNs may be engulfed by cancer cells contributing to a second wave of DOX-mediated cytotoxicity following pH-triggered DOX release.

Bioinspired synthesis of high-performance nanocomposite imprinted membrane by a polydopamine-assisted metal-organic method

Significant efforts have been focused on the functionalization and simplification of membrane-associated molecularly imprinted materials, which can rapidly recognize and separate specific compound. However, issues such as low permselectivity and unstable composite structures are restricting it from developing stage to a higher level. In this work, with the bioinspired design of polydopamine (pDA)-assisted inorganic film, we present a novel molecular imprinting strategy to integrate multilevel nanocomposites (Ag/pDA) into the porous membrane structure. The molecularly imprinted nanocomposite membranes were then obtained through an in situ photoinitiated ATRP method by using tetracycline (TC) as the template molecule. Importantly, attributing to the formation of the Ag/pDA-based TC-imprinted layers, largely enhance TC-rebinding capacity (35.41mg/g), adsorption selectivity and structural stability (still maintained 92.1% of the maximum adsorption capacity after 10 cycling operations) could been easily achieved. Moreover, largely enhanced permselectivity performance toward template molecule (the permeability factor β values were also more than 5.95) was also obtained. Finally, all synthesis methods were conducted in aqueous solution at ambient temperature, which was environmental friendly for scaling up without causing pollution.

A simple and sensitive surface molecularly imprinted polymers based fluorescence sensor for detection of λ-Cyhalothrin.

In this study, surface molecularly imprinted YVO4:Eu(3+) nanoparticles with molecular recognitive optosensing activity were successfully prepared by precipitation polymerization using λ-Cyhalothrin (LC) as template molecules, methacrylic acid and ethylene glycol dimethacrylate as the polymerization precursors which could complex with template molecules, and the material has been characterized by SEM, TEM, FT-IR, XRD, TGA and so on. Meanwhile, the as-prepared core-shell structured nanocomposite (YVO4:Eu(3+)@MIPs), which was composed of lanthanide doped YVO4:Eu(3+) as fluorescent signal and surface molecular imprinted polymers as molecular selective recognition sites, could selectively and sensitively optosense the template molecules. After the experimental conditions were optimized, two linear relationship were obtained covering the concentration range of 2.0-10.0 μM and 10.0-90.0 μM, and the limit of detection (LOD) for LC was found to be 1.76 μM. Furthermore, a possible mechanism was put forward to explain the fluorescence quenching of YVO4:Eu(3+)@MIPs. More importantly, the obtained sensor was proven to be suitable for the detection of residues of LC in real examples. And the excellent performance of this sensor will facilitate future development of rapid and high-efficiency detection of LC.

Fabrication and evaluation of artemisinin-imprinted composite membranes by developing a surface functional monomer-directing prepolymerization system.

Inspired by a surface functional monomer-directing prepolymerization system, a straightforward and effective synthesis method was first developed to prepare highly regenerate and perm-selective molecularly imprinted composite membranes of artemisinin (Ars) molecules. Attributing to the formation of the prepolymerization system, Ars molecules are attracted and bound to the membrane surface, hence promoting the growth of homogeneous and high-density molecular recognition sites on the surface of membrane materials. Afterward, a two-step-temperature imprinting procedure was carried out to prepare the novel surface functional monomer capping molecularly imprinted membranes (FMIMs). The as-prepared FMIMs not only exhibited highly adsorption capacity (11.91 mg g(-1)) but also showed an outstanding specific selectivity (imprinting factor α is 4.50) and excellent perm-selectivity ability (separation factor β is 10.60) toward Ars molecules, which is promising for Ars separation and purification.

Preparation of a Two-Dimensional Ion-Imprinted Polymer Based on a Graphene Oxide/SiO2 Composite for the Selective Adsorption of Nickel Ions

In the present work, a novel two-dimensional (2D) nickel ion-imprinted polymer (RAFT-IIP) has been successfully synthesized based on the graphene oxide/SiO2 composite by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The imprinted materials obtained are characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that the thermal stability of the graphene oxide/SiO2 composite is obviously higher than that of graphene oxide. RAFT-IIP possesses an excellent 2D homogeneous imprinted polymer layer, which is a well-preserved unique structure of graphene oxide/SiO2. Owing to the intrinsic advantages of RAFT polymerization and 2D imprinted material, RAFT-IIP demonstrate a superior specific adsorption capacity (81.73 mg/g) and faster adsorption kinetics (30 min) for Ni(II) in comparison to the ion-imprinted polymer prepared by traditional radical polymerization and based on the common carbon material. Furthermore, the adsorption isotherm and selectivity toward Ni(II) onto RAFT-IIP and nonimprinted polymer (NIP) are investigated, indicating that RAFT-IIP has splendid recognizing ability and a nearly 3 times larger adsorption capacity than that of NIP (30.94 mg/g). Moreover, a three-level Box-Behnken experimental design with three factors combining the response surface method is utilized to optimize the desorption process. The optimal conditions for the desorption of Ni(II) from RAFT-IIP are as follows: an HCl-type eluent, an eluent concentration of 2.0 mol/L, and an eluent volume of 10 mL.

Monodisperse magnetic ion imprinted polymeric microparticles prepared by RAFT polymerization based on γ-Fe2O3@meso-SiO2 nanospheres for selective solid-phase extraction of Cu(II) in water samples

Utilising a general protocol for making surface-imprinted core–shell microparticles via a RAFT-mediated approach, we developed a Cu(II) imprinted polymer with a novel magnetic nanosphere, γ-Fe2O3@meso-SiO2, as support. Attributed to the controlled/living polymerization mechanism of the RAFT polymerization process, the Cu(II) imprinted polymer prepared by RAFT polymerization (IIP-RAFT) presented a more well-defined morphology, more mono-dispersed properties, and much higher magnetic responsiveness, compared to the Cu(II) imprinted polymer prepared by traditional free-radical polymerization (IIP-TP). Moreover, in the static saturation binding experiments, a higher binding capacity of IIP-RAFT (210 mg g−1) than IIP-TP (145 mg g−1) was also found. Afterwards, a series of adsorption experiments were carried out to systematically evaluate the adsorption performance of the as-prepared IIP-RAFT. And the results showed that IIP-RAFT exhibited excellent selectivity, good reusability and desirable dynamic adsorption behavior, and could be an ideal candidate for SPE sorbents for the removal of Cu(II) in real wastewater.

Synthesis of novel ion-imprinted polymers by two different RAFT polymerization strategies for the removal of Cs(I) from aqueous solutions

In this work, two novel Cs(I) ion-imprinted polymers (Cs(I)-IIP1 and Cs(I)-IIP2) have been prepared by surface imprinting technique based on support matrix of SBA-15. The strategy was carried out by introducing two different reversible addition–fragmentation chain transfer (RAFT) polymerization including using the free RAFT agent in solution and surface-anchored RAFT agent with appropriate initiation method, which is expected to generate a well-defined surface ion-imprinted polymer with excellent adsorption capacity. The materials were verified by FT-IR, SEM, TEM, nitrogen adsorption–desorption and TGA. Owing to the intrinsic advantages of surface-anchored RAFT polymerization, the resultant surface ion-imprinted polymer (Cs(I)-IIP2) exhibited more homogeneous and thinner polymer layer (15 nm) with excellent macrostructure in comparison to Cs(I)-IIP1 (75 nm) prepared by using the free RAFT agent in solution. Furthermore, the adsorption capacity of both polymers are compared, indicating that Cs(I)-IIP2 displays higher adsorption property and excellent selectivity for Cs(I).