Preparation of Azobenzene-Containing Polymer Membranes That Function in Photoregulated Molecular Recognition

Pipette-like action of a reusable and NIR light-responsive film for the aspiration and removal of viable cancer cells

A reusable and NIR light-responsive composite membrane is developed to capture/release viable cancer cells.

Responsive Polymers as Smart Nanomaterials Enable Diverse Applications

Responsive polymers undergo reversible or irreversible physical or chemical modifications in response to a change in environment or stimulus, e.g., temperature, pH, light, and magnetic or electric fields. Polymeric nanoparticles (NPs), which constitute a diverse set of morphologies, including micelles, vesicles, and core-shell geometries, have been successfully prepared from responsive polymers and have shown great promise in applications ranging from drug delivery to catalysis. In this review, we summarize pH, thermo-, photo-, and enzymatic responsiveness for a selection of polymers. We then discuss the formation of NPs made from responsive polymers. Finally, we highlight how NPs and other nanomaterials are enabling a wide range of smart applications with improved efficiency, as well as improved sustainability and recyclability of polymeric systems.

Ultrasensitive separation of methylprednisolone acetate using a photoresponsive molecularly imprinted polymer incorporated polyester dendrimer based on magnetic nanoparticles

We developed an approach for the use of polyester dendrimer during the imprinting process to raise the number of recognized sites in the polymer matrix and improve its identification ability. Photoresponsive molecularly imprinted polymers were synthesized on modified magnetic nanoparticles involving polyester dendrimer which uses the reactivity between allyl glycidyl ether and acrylic acid for the high-yielding assembly by surface polymerization. The photoresponsive molecularly imprinted polymers were constructed using methylprednisoloneacetate as the template, water-soluble azobenzene involving 5-[(4, 3-(methacryloyloxy) phenyl) diazenyl] dihydroxy aniline as the novel functional monomer, and ethylene glycol dimethacrylate as the cross-linker. Through the evaluation of a series of features of spectroscopic and nano-structural, this sorbent showed excellent selective adsorption, recognition for the template, and provided a highly selective and sensitive strategy for determining the methylprednisoloneacetate in real and pharmaceutical samples. In addition, this sorbent according to good photo-responsive features and specific affinity to methylprednisoloneacetate with high recognition ability, represented higher binding capacity, a more extensive specific area, and faster mass transfer rate than its corresponding surface molecularly imprinted polymer.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Ultrasensitive detection of bisphenol A in aqueous media using photoresponsive surface molecular imprinting polymer microspheres

A photoresponsive SMIP was prepared for photocontrolled detection of trace bisphenol A in aqueous media with simplicity and good efficiency.

Molecularly imprinted polymer microspheres containing photoswitchable spiropyran-based binding sites

A versatile approach for the preparation of photoswitchable molecularly imprinted polymers (MIPs) is proposed where the selective recognition and the photoresponsive function are assumed by two different monomers. As a proof of concept, MIP microspheres were synthesized by precipitation polymerization for recognizing terbutylazine, a triazine-type herbicide. Formation of the selective binding sites was based upon H-bonding interactions between the template and the functional monomer methacrylic acid, whereas a polymerizable spiropyran unit was incorporated into the polymer matrix to provide light-controllable characteristics. A trifunctional monomer, trimethylolpropane trimethacrylate, was used as a cross-linker. The imprinted particles exhibited considerable morphological differences compared to their nonimprinted counterparts as observed by scanning electron microscopy. The imprinting effect was confirmed by equilibrium rebinding studies. The photoresponsiveness of the polymer particles was visualized by fluorescence microscopy and further characterized by spectroscopy. The template binding behavior could be regulated by alternating UV and visible light illumination when analyte release and uptake was observed, respectively. Binding isotherms fitted by the Freundlich model revealed the photomodulation of the number of binding sites and their average affinity. This facile synthetic approach may give an attractive starting point to endow currently existing highly selective MIPs with photoswitchable properties, thereby extending the scope of spiropyran-based photoresponsive smart materials.

Molecularly Imprinted Hydrogels for Affinity-controlled and Stimuli-responsive Drug Delivery

The performance of smart or intelligent hydrogels as drug-delivery systems (DDSs) can be notably improved if the network is endowed with high-affinity receptors for the therapeutic molecule. Conventional molecular imprinting technology aims to create tailored binding pockets (artificial receptors) in the structure of rigid polymers by means of a template polymerization, in which the target molecules themselves induce a specific arrangement of the functional monomers during polymer synthesis. Adaptation of this technology to hydrogel synthesis implicates the optimization of the imprinting pocket to be able to recover the high-affinity conformation when distorted by swelling or after the action of a stimulus. This chapter analyzes the implementation of the molecular imprinting technology to the synthesis of both non-responsive and responsive loosely cross-linked hydrogels, and provides recent examples of the suitability of the imprinted networks to attain affinity-controlled, activation-controlled or stimuli-triggered drug and protein release.

Azobenzene-containing molecularly imprinted polymer microspheres with photo- and thermoresponsive template binding properties in pure aqueous media by atom transfer radical polymerization

A facile, general, and highly efficient approach to obtain azobenzene (azo)-containing molecularly imprinted polymer (MIP) microspheres with both photo- and thermoresponsive template binding properties in pure aqueous media is described for the first time, which involves the first synthesis of "living" azo-containing MIP microspheres with surface-immobilized alkyl halide groups via atom transfer radical precipitation polymerization (ATRPP) and their subsequent modification via surface-initiated atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAm). The successful grafting of poly(NIPAAm) (PNIPAAm) brushes onto the obtained MIP microspheres was confirmed by FT-IR, SEM, water dispersion stability and static contact angle studies, and template binding experiments. The introduction of PNIPAAm brushes onto the azo-containing MIP microspheres significantly improved their surface hydrophilicity and imparted thermoresponsive properties to them, leading to their pure water-compatible and thermoresponsive template binding properties. In addition, the binding affinity of the imprinted sites in the grafted azo-containing MIP microspheres was found to be photoresponsive toward the template in pure water, and this photoregulation process proved to be highly repeatable under photoswitching conditions.

Light responsive polymer membranes: a review

In recent years, stimuli responsive materials have gained significant attention in membrane separation processes due to their ability to change specific properties in response to small external stimuli, such as light, pH, temperature, ionic strength, pressure, magnetic field, antigen, chemical composition, and so on. In this review, we briefly report recent progresses in light-driven materials and membranes. Photo-switching mechanisms, valved-membrane fabrication and light-driven properties are examined. Advances and perspectives of light responsive polymer membranes in biotechnology, chemistry and biology areas are discussed.

Mimicking Biological Delivery Through Feedback-Controlled Drug Release Systems Based on Molecular Imprinting

Intelligent drug delivery systems (DDS) are able to rapidly detect a biological event and respond appropriately by releasing a therapeutic agent; thus, they are advantageous over their conventional counterparts. Molecular imprinting is a promising area that generates a polymeric network which can selectively recognize a desired analyte. This field has been studied for a variety of applications over a long period of time, but only recently has it been investigated for biomedical and pharmaceutical applications. Recent work in the area of molecularly imprinted polymers in drug delivery highlights the potential of these recognitive networks as environmentally responsive DDS that can ultimately lead to feedback controlled recognitive release systems.

Synthesis and Photoresponsive Properties of a Molecularly Imprinted Polymer

A photoresponsive molecularly imprinted polymer was prepared from a di(ureidoethylenemethacrylate)azobenzene monomer, using a methotrexate analogue as template. Photoisomerization of the 3D crosslinked polymer matrix allowed switching the substrate affinity by altering the geometry and spatial arrangement of the receptor binding sites. As a result, controlled release and uptake of the template (or analogous ligands) were obtained.

Photoresponsive porphyrin-imprinted polymers prepared using a novel functional monomer having diaminopyridine and azobenzene moieties

A novel photoresponsive functional monomer bearing diaminopyridine and azobenzene moieties was synthesized and applied to the preparation of photo-regulated molecularly imprinted polymers, which can recognize porphyrin derivatives through hydrogen bonding. The binding affinity of the imprinted cavities was regulated by UV irradiation, suggesting that azobenzene groups located inside the binding sites worked as photosensitizers and the trans-cis isomerization could regulate the affinity for the target compounds. Repetitive binding of the target compound to trans-IP and cis-IP was directly monitored by slab optical waveguide spectroscopy and the photo-mediated regulation of binding affinity was successfully confirmed.