Photoreactive Polymer Research Articles

Highly Photoreactive Semiconducting Polymers with Cascade Intramolecular Singlet Oxygen and Energy Transfer for Cancer-Specific Afterglow Theranostics.

Afterglow luminescence provides ultrasensitive optical detection by minimizing tissue autofluorescence and increasing the signal-to-noise ratio. However, due to the lack of suitable unimolecular afterglow scaffolds, current afterglow agents are nanocomposites containing multiple components with limited afterglow performance and have rarely been applied for cancer theranostics. Herein, we report the synthesis of a series of oxathiine-containing donor-acceptor block semiconducting polymers (PDCDs) and the observation of their high photoreactivity and strong near-infrared (NIR) afterglow luminescence. We reveal that PDCDs absorb NIR light to undergo a photodynamic process to generate singlet oxygen (1O2), which intramolecularly transfers to and efficiently reacts with the oxathiine block to form the afterglow oxathiine intermediates due to the low Gibbs free energy changes required for this photoreaction. Following intramolecular afterglow energy transfer from the oxathiine donor block to the acceptor block, NIR afterglow emission is produced from PDCDs. Owing to the efficient cascade intramolecular photochemical process, PDCD-based nanoparticles achieve a higher brightness and longer NIR emission compared to most reported afterglow agents, even after ultrashort photoirradiation for only 3 s. Furthermore, the cascade photochemical process within PDCD can be inhibited after bioconjugation with a quencher-linked peptide. This allows the construction of a cancer-activatable afterglow theranostic probe (CATP) that only switches on the afterglow signal and photodynamic function in the presence of a cancer-overexpressed enzyme. Thereby, CATP represents the first afterglow phototheranostic probe that permits cancer-specific detection and photodynamic cancer therapy under preclinical settings. In summary, this study provides a molecular guideline to develop afterglow probes from photoreactive polymers.

Chemically and geometrically programmable photoreactive polymers for transformational humidity-sensitive full-color devices

Humidity-sensitive structural color has emerged as a promising technology due to its numerous advantages that include fast response, intuitiveness, stand-alone capability, non-toxicity, as well as resistance to thermal and chemical stresses. Despite immense technological advancements, these structural colors lack the ability to present independent multiple images through transformation. Herein, we present an approach to address this constraint by introducing a chemically and geometrically programmable photoreactive polymer which allows preparation of transformational humidity-sensitive full-color devices. Utilizing azido-grafted carboxymethyl cellulose (CMC-N3) allows adjustments in swelling properties based on the grafting ratio (Γ) of azido groups upon UV-induced crosslinking. Also, the distinctive photo-curability of the polymer enables precise geometric control to achieve vivid colors in combination with disordered plasmonic cavities. Our work culminates in the development of an advanced anti-counterfeiting multiplexer capable of displaying different full-color images with variation in humidity levels. The showcased color displays signify pivotal breakthroughs in tunable optical technologies, illustrating how chemical modifications in hydrogels provides additional degrees of freedom in the design of advanced optical devices.

Anisotropic adhesive interface formed by the spontaneous orientation behavior of liquid crystal polymers

Abstract Adhesive layers were prepared using photoreactive polymer liquid crystals and their application as dismantled adhesives, based on the change in thermal properties associated with photoisomerization, was investigated. Anisotropy in adhesive strength was successfully achieved by controlling the alignment of the liquid crystal using a polyimide alignment film. Furthermore, anisotropy in the adhesive strength due to photoalignment was investigated using the axis-selective photoreactivity of polymer liquid crystals to linearly polarized light.

Visible Light Induced Interfacial Photo-Cross-Linking for Fabrication of Polymer Capsules Using Photoreactive Polymers with Substituted Cinnamates

Visible Light Induced Interfacial Photo-Cross-Linking for Fabrication of Polymer Capsules Using Photoreactive Polymers with Substituted Cinnamates

Reversible single-crystal to single-crystal photoreaction between a coordination comb and a ladder displays photo-switchable fluorescence

A unique coordination polymer can transform between comb-like and ladder-like bistable structures through reversible single-crystal-to-single-crystal photoreaction and exhibit photo-switchable fluorescence.

Effect of Residue Acrylic Monomers in Synthesized Solvent-Free Photoreactive Pressure-Sensitive Adhesives on the Main Properties of Transfer Tapes Applied to Joining Wooden Elements.

This publication describes the influence of residue monomers in synthesized pressure-sensitive adhesives based on acrylics on their main properties-tack, peel adhesion, shear strength and shrinkage-in the form of transfer tapes used for joining wooden elements in the furniture industry. The discussed carrier-free adhesive tapes are synthesized via photo-crosslinking and photopolymerization with UV radiation of the photoreactive prepolymers sandwiched between two adhesive siliconized polyester films. The simultaneous crosslinking and polymerization processes carried out under UV lamps placed simultaneously above and below the crosslinked photoreactive polymer layer lead to the production of a carrier-free adhesive film. The preliminary target of these studies was to investigate how the intensity of UV radiation and the time of its exposure affect the viscosity of the photoreactive compositions and the content of unreacted monomers in them. Next, the influence of the crosslinking agent concentration and UV irradiation time on the content of unreacted monomers after the crosslinking process was tested. The last step of the studies was the investigation of the influence of the residue monomer concentration on the application properties of the obtained pressure-sensitive adhesive layers. The typical PSA application properties were tested on the wood samples: tack, peel adhesion, shear strength (cohesion) and shrinkage.

Photoassisted Surface Modification with Zwitterionic Phosphorylcholine Polymers for the Fabrication of Ideal Biointerfaces.

Surface modification using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers is commonly performed to fabricate interfaces that reduce nonspecific fouling by biomolecules and cells. Accordingly, several clinically used devices, such as guide wires, stents, oxygenators, left ventricular assist devices, and microcatheters have been modified using MPC polymers. The specific types of surface modifications vary across substrates and applications. Recently, photoreactions have garnered attention for surface modification due to their stability and tunability. This review highlights various studies that employed photoreactions to modify surfaces using MPC polymers, especially photoinduced graft polymerization of MPC. In addition to antifouling materials, several micromanipulated, long-lasting hydrophilic, and super antiwear surfaces are summarized. Furthermore, several photoreactive MPC polymers that can be used to control interactions between biomolecules and materials are presented along with their potential to form selective recognition surfaces that target biomolecules for biosensors and diagnostic devices.

Photoreactive silver-containing supramolecular polymers that form self-assembled nanogels for efficient antibacterial treatment

In this study, an efficient synthetic strategy and potential route to obtain a photo-reactive silver-containing cytosine-functionalized polypropylene glycol polymer (Ag-Cy-PPG) was developed by combining a hydrophilic oligomeric polypropylene glycol (PPG) backbone with dual pH-sensitive/photo-reactive cytosine-silver-cytosine (Cy-Ag-Cy) linkages. The resulting photo-responsive Ag-Cy-PPG holds great promise as a multifunctional biomedical material that generates spherical-like nanogels in water; the nanogels exhibit high antibacterial activity and thus may significantly enhance the efficacy of antibacterial treatment. Due to the formation of photo-dimerized Cy-Ag-Cy cross-linkages after UV irradiation, Ag-Cy-PPG converts into water-soluble cross-linked nanogels that possess a series of interesting chemical and physical properties, such as intense and stable fluorescence behavior, highly sensitive pH-responsive characteristics, on/off switchable phase transition behavior, and well-controlled release of silver ions (Ag+) in mildly acidic aqueous solution. Importantly, antibacterial tests clearly demonstrated that irradiated Ag-Cy-PPG nanogels exhibited strong antibacterial activity at low doses (MIC values of < 50 μg/mL) against gram-positive and gram-negative bacterial pathogens, whereas non-irradiated Ag-Cy-PPG nanogels did not inhibit the viability of bacterial pathogens. These results indicate that irradiated Ag-Cy-PPG nanogels undergo a highly sensitive structural change in the bacterial microenvironment due to their relatively unstable π-conjugated structures (compared to non-irradiated nanogels); this change results in a rapid structural response that promotes intracellular release of Ag+ and induces potent antibacterial ability. Overall, this newly created metallo-supramolecular system may potentially provide an efficient route to dramatically enhance the therapeutic effectiveness of antibacterial treatments.

Fluorescent Waveguide Lattices for Enhanced Light Harvesting and Solar Cell Performance.

We present the properties and performance of fluorescent waveguide lattices as coatings for solar cells, designed to address the significant mismatch between the solar cell's spectral response range and the solar spectrum. Using arrays of microscale visible light optical beams transmitted through photoreactive polymer resins comprising acrylate and silicone monomers and fluorescein o,o'-dimethacrylate comonomer, we photopolymerize well-structured films with single and multiple waveguide lattices. The materials exhibited bright green-yellow fluorescence emission through down-conversion of blue-UV excitation and light redirection from the dye emission and waveguide lattice structure. This enables the films to collect a broader spectrum of light, spanning UV-vis-NIR over an exceptionally wide angular range of ±70°. When employed as encapsulant coatings on commercial silicon solar cells, the polymer waveguide lattices exhibited significant enhancements in solar cell current density. Below 400 nm, the primary mode of enhancement is through down-conversion and light redirection from the dye emission and collection by the waveguides. Above 400 nm, the primary modes of enhancement were a combination of down-conversion, wide-angle light collection, and light redirection from the dye emission and collection by the waveguides. Waveguide lattices with higher dye concentrations produced more well-defined structures better suited for current generation in encapsulated solar cells. Under standard AM 1.5 G irradiation, we observed nominal average current density increases of 0.7 and 1.87 mA/cm2 for single waveguide lattices and two intersecting lattices, respectively, across the full ±70° range and reveal optimal dye concentrations and suitable lattice structures for solar cell performance. Our findings demonstrate the significant potential of incorporating down-converting fluorescent dyes in polymer waveguide lattices for improving the current spectral and angular response of solar cell technologies toward increasing clean energy in the energy grid.

One step antimicrobial coatings for medical device applications based on low fouling polymers containing selenium nanoparticles

All indwelling and implantable medical devices are associated with a risk of infection, and antimicrobial technologies that can provide effective protection against pathogen colonization and biofilm formation over the lifetime of these devices are urgently required. Here, strategies that combine multiple layers of defense have emerged as particularly promising. We have combined a copolymer coating based on 2-hydroxypropyl acrylamide and N-benzophenone acrylamide with novel, optimally sized antimicrobial selenium nanoparticles (Se NPs). The photoreactive polymer allowed the crosslinking and covalent anchoring of the coating in a single step, and the exceptionally low attachment of bacteria was demonstrated. Our results also demonstrated that the incorporation of the antimicrobial Se NPs provides the coating with an additional bactericidal functionality towards the Gram-positive bacteria S. aureus and E. faecalis, which are widely recognized as the most prevalent pathogens linked to medical device-associated infections and more broadly nosocomial infections. The multiple layers of defense provided effective inhibition of the growth of both bacteria strains in areas where the coating had been removed, as well as in the supernatant. Moreover, our results demonstrate the feasibility to modulate the release of Se NPs from the coating by tailoring coating parameters such as the nanoparticle to polymer ratio. Our cytotoxicity study further confirmed the superior biocompatibility of Se NPs compared to the well-established silver nanoparticles over a broad concentration range. Our multifunctional coating approach is expected to be translated into medical device applications due to its ease of manufacture and effective antimicrobial protection.

Recent Progress in Photoresponsive Biomaterials.

Photoresponsive biomaterials have garnered increasing attention recently due to their ability to dynamically regulate biological interactions and cellular behaviors in response to light. This review provides an overview of recent advances in the design, synthesis, and applications of photoresponsive biomaterials, including photochromic molecules, photocleavable linkers, and photoreactive polymers. We highlight the various approaches used to control the photoresponsive behavior of these materials, including modulation of light intensity, wavelength, and duration. Additionally, we discuss the applications of photoresponsive biomaterials in various fields, including drug delivery, tissue engineering, biosensing, and optical storage. A selection of significant cutting-edge articles collected in recent years has been discussed based on the structural pattern and light-responsive performance, focusing mainly on the photoactivity of azobenzene, hydrazone, diarylethenes, and spiropyrans, and the design of smart materials as the most targeted and desirable application. Overall, this review highlights the potential of photoresponsive biomaterials to enable spatiotemporal control of biological processes and opens up exciting opportunities for developing advanced biomaterials with enhanced functionality.

Photo-reactive polymers for the immobilisation of epidermal growth factors.

Photo-reactive polymers are important for biomaterials, including devices with a 3D-structure. Here, different types of photo-reactive polymers were prepared and utilised for immobilisation of growth factors. They were synthesised by conjugation of gelatin with the azidophenyl group or by copolymerisation of the azidophenyl group-coupled methacrylate with poly(ethylene glycol) methacrylate. The azidophenyl content and the zeta potential of the prepared polymers were measured. After spin coating of polymers, the thickness and the water contact angle of coated layers were measured. The amount of the immobilised epidermal growth factor (EGF) was determined using fluorescence labelling. Cell adhesion responded to the nature of photo-reactive polymers but did not depend on the immobilised EGF. However, cell growth was dependent on the amount of immobilised EGF and was significantly affected by the nature of photo-reactive polymers. The study shows that the properties of the photo-immobilisation matrix significantly influence the biological activity.

Reversible Single-Crystal-to-Single-Crystal Transformation of a Coordination Polymer through Solar-Switchable Cycloaddition and Cycloreversion Reaction.

Reversible covalent reactions within crystalline complexes are powerful tools for the design and developing of new generation of reusable smart materials. In this work, a unique photoreactive olefin-containing metal-organic coordination polymer [Ag2(2,3-ppe)2(1,3-bdc)]n (1) was prepared by the hydrothermal reaction between AgNO3, 1-(2-pyridyl)-2-(3-pyridyl)ethylene (2,3-ppe), and 1,3-benzenedicarboxylic acid (1,3-H2bdc). When exposed to sunlight, 1 can undergo single-crystal-to-single-crystal (SCSC) transformation to form [Ag2(dpdpcb)(1,3-bdc)]n (1a, dpdpcb = 1,3-di(2-pyridyl)-2,4-di(3-pyridyl)cyclobutane) through a [2 + 2] cycloaddition reaction. 1a can regenerate into 1 via the cycloreversion reaction based on the thermal effect of sunlight. Such a metal-organic complex exhibits interesting fluorescence switching behavior during the unprecedented fully solar-controlled reversible SCSC reaction, which makes it possible to be applied to the fields of optical memory storage and anti-counterfeiting.

Substrate-Independent Maskless Writing of Functionalized Microstructures Using CHic Chemistry and Digital Light Processing.

Maskless photolithography based on digital light processing (DLP) is an attractive technique for the rapid, flexible, and cost-effective fabrication of complex structures with arbitrary surface profiles on the microscale. In this work, we introduce a new material system for structure formation by DLP that is based on photoreactive polymers for the local and light-induced C,H-insertion cross-linking (CHic). This approach allows a simple and versatile generation of microstructures with a broad spectrum of geometries and chemistries irrespective of the nature of the chosen substrates and thus allows direct writing of surface functionalization patterns with high spatial control. The CHicable prepolymer is first coated on a substrate to form a solvent-free (glassy) film, and then the DLP system patterns the light with arbitrary shape to induce local cross-linking of the prepolymer. Using this method, the desired structures with complex features with a lateral resolution of several microns and a topography of tens of nanometers could be fabricated within 30 s. Furthermore, the universal applicability of the CHic reaction enables the printing on a wide variety of substrates, which greatly broadens the using scenarios of this printing approach.

Photoreactive polymer composite for selective oxidation of benzene to phenol

In this work, the photocatalytic hydroxylation of benzene to phenol in presence of H2O2 is studied using, for the first time, a photoreactive polymer composite based on N-doped TiO2 (N-TiO2) embedded into a monolithic syndiotactic polystyrene aerogel (N-TiO2/sPS, 10/90 w/w). N-TiO2/sPS is able to enhance the phenol selectivity and yield compared to bare N-TiO2. The best results in terms of selectivity (98%) and phenol yield (57%) are achieved under visible light in acidic conditions (pH=2), preserving a high benzene conversion (58%). In addition, N-TiO2/sPS is recovered from the aqueous solution containing the reaction products and reused several times without significant loss of photoreactivity and reduction of phenol yield. The described photoreactive solid phase represents a "proof of concept" that could allow a significant leap forward in the development of innovative green processes for the selective oxidation of aromatic hydrocarbons under mild conditions.

Rapid and quantitative detection of multiple antibodies against SARS-CoV-2 mutant proteins by photo-immobilized microarray.

A rapid automatic quantitative diagnostic system for multiple SARS-CoV-2 mutant protein-specific antibodies was developed using a microarray with photoreactive polymers. Two types of photoreactive polymers, phenylazide and polyoxyethylene, were prepared. The polymers were coated on a plastic plate. Aqueous solutions of mutant virus proteins were microspotted on the coated plate and immobilized by photoirradiation. Virus-specific IgG in the serum or blood was automatically assayed using an instrument that we developed for pipetting, reagent stirring, and washing. The results highly correlated with those of the conventional enzyme-linked immunoassay or immunochromatography. This system was successfully used to test the sera or blood from the patients recovered from the infection and the vaccinated individuals. The recovered individuals had antibodies against the nucleoprotein, in contrast to the vaccinated individuals. The amount of antibodies produced decreased with an increase in virus mutation. Blood collected from the fingertip (5 μL) and a test period of 8 min were sufficient conditions for conducting multiple antibody assays. We believe that our system would facilitate rapid and quantitative automatic assays and aid in the diagnosis of various viral infectious diseases and assessment of the immune status for clinical applications.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s44211-022-00161-z.

Multidirectional Polymer Waveguide Lattices for Enhanced Ultrawide-Angle Light Capture in Silicon Solar Cells.

We report the synthesis and characterization of a polymer thin-film structure consisting of two intersecting broadband optical waveguide lattices, and its performance in wide-angle optical energy collection and conversion in silicon solar cells. The structures are synthetically organized via the concurrent irradiation of photoreactive polymer blends by two arrays of intersecting, microscale optical beams transmitted through the medium. Through optical beam-induced photopolymerization and photopolymerization-induced phase separation, well-organized lattices are produced comprising of cylindrical core–cladding waveguide architectures that intersect one another. The optical waveguide properties of the lattices transform the transmission characteristics of the polymer film so that incident optical energy is collected and transmitted along the waveguide axes, rather than their natural directions dictated by refraction, thereby creating efficient light-collecting capability. The embedded structures collectively impart their wide-angle acceptance ranges to enable the film to efficiently collect and interact with light over a large angular range (±70°). When employed as the encapsulant material for a commercial silicon solar cell, the novel light collection and transmission properties result in greater wide-angle conversion efficiency and electrical current density, compared to a single vertically aligned waveguide array. The sustained and greater conversion of light afforded by the encapsulating optical material promises to increase solar cell performance by enabling ultrawide-angle solar energy conversion.

Photoreactive polymer and C,H-insertion reaction to tailor the properties of CHA/gelatin-based scaffold

A series of photoreactive polymers containing poly(N,N-dimethylacrylamide) and 2-hydroxy-(4-methacryloyloxybenzophenone), P(DMAA-n%MABP-OH), was explored to modify sheet-formed carbonated hydroxyapatite/gelatin (CHA/gelatin) scaffold. Under UV-light illumination, the benzophenones react with any C–H bonds in their vicinity through a C,H-insertion mechanism, enabling PDMAA-based hydrogel formation that is covalently attached to the gelatin. NMR spectroscopy confirmed the chemical structure of P(DMAA-n%MABP-OH) polymers with aimed n = 1, 5, 10, while GPC determined their molecular masses. The benzophenone reactivity under UV-light illumination for 0–240 min. was demonstrated using UV-Vis spectroscopy at 240–400 nm. After immobilization of P(DMAA-n%MABP-OH) onto the CHA/gelatin scaffold, typical FTIR vibration bands of both compounds could be detected on the spectra of the modified scaffolds. SEM images showed that the scaffold is highly porous with approximately 100 µm thickness. P(DMAA-n%MABP-OH) addition led to 2–3 times increase in thickness and 15–19% mass addition. Furthermore, it was shown that chemical (degradation and Ca2+ release profile), physical (4−7 swelling index), mechanical (0.06−0.17 MPa wet tensile strength and 0.2−0.8 MPa elastic modulus), and biological (cell adhesion) properties of the scaffold could be tailored by varying the photocrosslinker content. Cytotoxicity test showed that all studied CHA/gelatin-based scaffolds were nontoxic (>80% cell viability).

Simulations of Structure and Morphology in Photoreactive Polymer Blends under Multibeam Irradiation

We present a theoretical study of the organization of photoreactive polymer blends under irradiation by multiple arrays of intersecting optical beams. In a simulated medium possessing an integrated intensity-dependent refractive index, optical beams undergo self-focusing and reduced divergence. A corresponding intensity-dependent increase in molecular weight induces polymer blend instability and consequent phase separation, whereby the medium can evolve into an intersecting waveguide lattice structure, comprising high refractive index cylindrical cores and a surrounding low refractive index medium (cladding). We conduct simulations for two propagation angles and a range of thermodynamic, kinetic, and polymer blend parameters to establish correlations to structure and morphology. We show that spatially correlated structures, namely, those that have a similar intersecting three-dimensional (3D) pattern as the arrays of intersecting optical beams, are achieved via a balance between the competitive processes of photopolymerization rate and phase separation dynamics. A greater intersection angle of the optical beams leads to higher correlations between structures and the optical beam pattern and a wider parameter space that achieves correlated structures. This work demonstrates the potential to employ complex propagating light patterns to create 3D organized structures in multicomponent photoreactive soft systems.

Carboxy-functionalized pH responsive capsule polymer particles fabricated by particulate interfacial photocrosslinking.

pH-responsive capsule particles show promise for various applications, such as self-healing materials, micro/nanoreactors, and drug delivery systems. Herein, carboxy-functionalized capsule polymer particles possessing neutral-alkaline pH responsive controlled release capability were newly fabricated by interfacial photocrosslinking of spherical photoreactive polymer [poly(2-carboxyethyl acrylate-co-2-cinnamoylethyl methacrylate): P(CEA-CEMA)] particles and a subsequent encapsulation process. Using P(CEA-CEMA) particles, the shell-crosslinked hollow polymer particles were fabricated by the particulate interfacial photocrosslinking procedure. Furthermore, the encapsulation of sulforhodamine B as a model dye into the hollow particles was also performed. Under acidic pH conditions, encapsulated molecules were stably retained in the P(CEA-CEMA) capsules with negligible release of sulforhodamine B. However, the encapsulated sulforhodamine B was gradually or drastically released from the capsule particles under neutral or basic conditions, respectively, indicating that the neutral-alkaline pH responsive controlled release from the capsules was successfully achieved by regulating the release kinetics. These results demonstrate that the fabrication routes of hollow and capsule particles based on particulate interfacial photocrosslinking can be successfully applied to carboxy-functionalized photoreactive polymer particles, and the capsule polymer particles possessing pH-responsive release properties under neutral-basic conditions were successfully fabricated.