Substituent Effects of Fluorescein on Photoredox Initiating Performance under Visible Light.

We demonstrated the effects of substituents in fluorescein on the photoredox catalytic performance under visible light. For the systematic investigation, the phenyl ring of fluorescein was substituted with six different functional groups (i.e., amine, amide, isothiocyanate, aminomethyl, bromo, or nitro group) at the 5- or 6-position. The fluorescein derivatives were carefully characterized through photophysical and electrochemical analyses. The substituent effects were estimated by comparing the photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) and N-vinylpyrrolidone (VP) in the presence of triethanolamine (TEOA) under aerobic conditions to that of intact fluorescein. As a result, the amine and nitro groups exhibited the lowest performances, presumably due to intramolecular photoinduced electron transfer (PET) promoted by the strong electron push-pull effect. The others, representative moderate or weak deactivators and activators, exhibited inferior performances than intact fluorescein, presumably owing to the more negative ΔGPET values, resulting in a decreased rate of intermolecular PET. These results are crucial for understanding the structure-performance relationship and the development of visible-light photoredox catalysts with improved performance and functionality.

Photoinitiated Free-Radical Polymerization of 4,5,6,7-Tetrahalogenated Fluoresceins.

We demonstrated the photoredox catalytic performances of fluorescein derivatives, bearing heavy halogen atoms (Br or I) on a benzoic acid group, using photoinitiated free-radical polymerization. 4,5,6,7-Tetrabromofluorescein and 4,5,6,7-tetraiodofluorescein were used as visible-light-photoredox catalysts to initiate polymerization of poly(ethylene glycol) diacrylate and N-vinylpyrrolidone in the presence of triethanolamine under aerobic conditions. Their photocatalytic performances were evaluated by the hydrogelation of photopolymerization both on the surface of an agarose film and in a liquid solution. The polymerization degree increased considerably in the following order: tetraiodofluorescein

Biochip Performances of Agarose, Poly(Oligo(Ethylene Glycol) Methacrylate), and Poly(2-Hydroxyethyl Methacrylate) Film on Glass Surfaces.

We demonstrate the biochip efficacies of three different polymer films (agarose, poly(oligo(ethylene glycol) methacrylate) (pOEGMA), and poly(2-hydroxyethyl metacharylate) (pHEMA) on microscopic glass surfaces. As a result, the non-biofouling performances increased in this order: agarose < pOEGMA < pHEMA, and the binding capabilities increased in this order: pHEMA < pOEGMA < agarose.

Synthetic Strategies for (-)-Cannabidiol and Its Structural Analogs.

(-)-Cannabidiol ((-)-CBD), a non-psychoactive phytocannabinoid from Cannabis, and its structural analogs have received growing attention in recent years because of their potential therapeutic benefits, including neuroprotective, anti-epileptic, anti-inflammatory, anxiolytic, and anti-cancer properties. (-)-CBD and its analogs have been obtained mainly based on extraction from the natural source; however, the conventional extraction-based methods have some drawbacks, such as poor quality control along with purification difficulty. Chemical-synthetic strategies for (-)-CBD could tackle these issues, and, additionally, generate novel (-)-CBD analogs that exhibit advanced biological activities. This review concisely summarizes the historic and recent milestones in the synthetic strategies for (-)-CBD and its analogs.

Surface Functionalization of Plastic Surfaces with Non-Biofouling Agarose Film to Develop a Chip-Based Platform.

We chemically functionalized several plastic surfaces using an agarose film for applying a protein chip. The chip performance was affected by the surface energy of each plastic after oxygen-plasma cleaning; as a result, polystyrene and polyethylene terephthalate showed a higher signal-to-noise ratio than did polypropylene. We envision that this study will help to develop a way to build biochips.

Solid-phase extraction of nerve agent degradation products using poly[(2-(methacryloyloxy)ethyl)trimethylammonium chloride] thin films.

In this study, a simple solid-phase extraction (SPE) technique was developed to extract organophosphonic acids as degradation products of nerve agents from aqueous samples for identification by instrumental analyses such as FT-IR, TOF-SIMs and GC-MS. To selectively extract the organophosphonic acids, we synthesized an anion exchange polymer film on a gold plate using surface-initiated controlled radical polymerization with 2-[(methacryloyloxy)ethyl]trimethylammonium chloride. Extraction of the organophosphonic acids onto the plates was successfully confirmed by polarized angle fourier transformation-infra red (FT-IR) spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry analyses. The limit of detection of the developed SPE method satisfied the detection limit of Chemical Warfare Agents verification criteria by FT-IR analysis. After optimization, the detection limit values were found to be between 0.1 and 0.4 µg mL-1, and the recovery ranged from 50% to 110% in aqueous solution containing various interference. In addition, the SPE process was successfully applied to the detection of pinacolyl methylphosphonic acid, the degradation product of soman, in the 35th Organization for Prohibition of Chemical Weapons proficiency test sample.

Iron gall ink revisited: hierarchical formation of Fe(iii)-tannic acid coacervate particles in microdroplets for protein condensation.

Inspiration from the iron gall ink leads to the efficient formation of Fe(iii)-tannic acid coacervate particles inside the phase-separated microdroplets that are derived from the aqueous PEG/dextran liquid-liquid phase separation system. This hierarchical self-assembly, in aid of the protein affinity of tannic acid, makes it possible to compartmentalize and condense proteins into a localized, compact space in the microdroplets.

Enzymatic film formation of nature-derived phenolic amines.

An enzyme-instructed method is developed for material-independent, cytocompatible coating of phenolic amines, inspired by melanogenesis found in nature. Tyrosinase-based film formation proceeds smoothly in an aqueous solution at neutral pH, and can use various phenolic amines including catecholamines, such as tyrosine, tyramine, dopamine, norepinephrine, and DOPA, as a coating precursor. Compared with polydopamine coating, the method is fast and efficient, and forms uniform films. Its high cytocompatibility is advantageously applied to cell-surface engineering, where chemically labile Jurkat cells are coated individually without any noticeable decrease in viability. Considering the huge potential of polyphenolic-based coatings, the strategy developed herein will provide an advanced tool for manipulating biological entities, including living cells, in biomedical and medicinal applications.

Cell-Surface Engineering for Advanced Cell Therapy.

Stem cells opened great opportunity to overcome diseases that conventional therapy had only limited success. Use of scaffolds made from biomaterials not only helps handling of stem cells for delivery or transplantation but also supports enhanced cell survival. Likewise, cell encapsulation can provide stability for living animal cells even in a state of separateness. Although various chemical reactions were tried to encapsulate stolid microbial cells such as yeasts, a culture environment for the growth of animal cells allows only highly biocompatible reactions. Therefore, the animal cells were mostly encapsulated in hydrogels, which resulted in enhanced cell survival. Interestingly, major findings of chemistry on biological interfaces demonstrate that cell encapsulation in hydrogels have a further a competence for modulating cell characteristics that can go beyond just enhancing the cell survival. In this review, we present a comprehensive overview on the chemical reactions applied to hydrogel-based cell encapsulation and their effects on the characteristics and behavior of living animal cells.

Systematic Study of Functionalizable, Non-Biofouling Agarose Films with Protein and Cellular Patterns on Glass Slides.

Herein we demonstrate a systematic investigation of chemically functionalizable, non-biofouling agarose films over large-area glass surfaces. Agarose films, prepared with various concentrations of aqueous agarose, were activated by using periodate oxidation to generate aldehyde groups at the termini of the agarose chains. The non-biofouling efficacy and binding capabilities of the activated films were evaluated by using protein and cellular patterning, performed by using a microarrayer, microcontact printing, and micromolding in capillaries. Characterization by using a fluorescence slide scanner and a scanning-probe microscope revealed that the pore sizes of the agarose films played an important role in achieving desirable film performance; the 0.2 wt % agarose film exhibited the optimum efficacy in this work.

Backfilling-Free Strategy for Biopatterning on Intrinsically Dual-Functionalized Poly[2-Aminoethyl Methacrylate-co-Oligo(Ethylene Glycol) Methacrylate] Films.

We demonstrated protein and cellular patterning with a soft lithography technique using poly[2-aminoethyl methacrylate-co-oligo(ethylene glycol) methacrylate] films on gold surfaces without employing a backfilling process. The backfilling process plays an important role in successfully generating biopatterns; however, it has potential disadvantages in several interesting research and technical applications. To overcome the issue, a copolymer system having highly reactive functional groups and bioinert properties was introduced through a surface-initiated controlled radical polymerization with 2-aminoethyl methacrylate hydrochloride (AMA) and oligo(ethylene glycol) methacrylate (OEGMA). The prepared poly(AMA-co-OEGMA) film was fully characterized, and among the films having different thicknesses, the 35 nm-thick biotinylated, poly(AMA-co-OEGMA) film exhibited an optimum performance, such as the lowest nonspecific adsorption and the highest specific binding capability toward proteins.

Micro/Nanostructured Films and Adhesives for Biomedical Applications.

The advanced technologies available for micro/nanofabrication have opened new avenues for interdisciplinary approaches to solve the unmet medical needs of regenerative medicine and biomedical devices. This review highlights the recent developments in micro/nanostructured adhesives and films for biomedical applications, including waterproof seals for wounds or surgery sites, drug delivery, sensing human body signals, and optical imaging of human tissues. We describe in detail the fabrication processes required to prepare the adhesives and films, such as tape-based adhesives, nanofilms, and flexible and stretchable film-based electronic devices. We also discuss their biomedical functions, performance in vitro and in vivo, and the future research needed to improve the current systems.

Immobilization of Antibody on a Cyclic Olefin Copolymer Surface with Functionalizable, Non-Biofouling Poly[Oligo(Ethylene Glycol) Methacrylate].

We report a perfluoroaryl azide-based photoreaction for synthesizing functionalizable and nonbiofouling poly[oligo(ethylene glycol) methacrylate] (pOEGMA) films on a chemically inert COC substrate, and an estimation of a surface coverage of the antibody immobilized onto the surface with the immuno-gold nanoparticles. The processes were confirmed by water contact angle measurement, FT-IR spectroscopy, and FE-SEM. The strategy demonstrated in this work could be applied to functionalizations of other polymeric materials and determination of the binding capacity of analytes in biosensors and microfluidic devices.

Direct patterning and biofunctionalization of a large-area pristine graphene sheet.

Direct patterning of streptavidin and NIH 3T3 fibroblast cells was successfully achieved over a large-area pristine graphene sheet on Si/SiO2 by aryl azide-based photografting with the conventional UV lithographic technique and surface-initiated, atom transfer radical polymerization of oligo(ethylene glycol) methacrylate.

One-step functionalization of zwitterionic poly[(3-(methacryloylamino)propyl)dimethyl(3-sulfopropyl)ammonium hydroxide] surfaces by metal-polyphenol coating.

The non-biofouling properties of a zwitterionic sulfobetaine polymer surface were easily made attractive to bioentities (e.g., proteins and cells) by metal-polyphenol coating, and spatio-selective functionalization of the zwitterionic polymer surface was achieved by using a soft lithographic technique.

Evaluating the sensitivity of hybridization-based epigenotyping using a methyl binding domain protein.

Hypermethylation of CpG islands in gene promoter regions has been shown to be a predictive biomarker for certain diseases. Most current methods for methylation profiling are not well-suited for clinical analysis. Here, we report the development of an inexpensive device and an epigenotyping assay with a format conducive to multiplexed analysis.

Non-biofouling polymeric thin films on solid substrates.

Nanoarchitectured polymer thin films are playing an increasingly pivotal role in a wide range of areas such as interfacial reactions, biomedical devices/implants, biosensors, food packing, and marine equipment. This review highlights recent research results in the field of the non-biofouling polymer films, including current understanding of the mechanisms of non-biofouling efficacy against bioentities (for example, proteins, cells, and bacteria) under different biological conditions. We also discuss current advances in the fabrication of non-biofouling coatings and micropatterns of cells on solid substrates and suggest a guideline when designing a non-biofouling polymer films, according to application requirements.

Balancing the initiation and molecular recognition capabilities of eosin macroinitiators of polymerization-based signal amplification reactions.

Coupling polymerization initiators to molecular recognition events provide the ability to amplify these events and detect them using the formation of a cross-linked polymer as an inexpensive readout that is visible to the unaided eye. The eosin-tertiary amine co-initiation system, activated by visible light, has proven utility in this context when an average of three eosin molecules are coupled to a protein detection reagent. The present work addresses the question of how detection sensitivity is impacted when the number of eosin molecules per binding event increases in the range of two to fifteen. Unlike in other initiation systems, a non-monotonic relationship is observed between the number of initiators per binding event and the observed detection sensitivity.

Binding behaviors of protein on spatially controlled poly[oligo(ethylene glycol) methacrylate] brushes grafted from mixed self-assembled monolayers on gold.

Binding behaviors of streptavidin were investigated with different lateral packing densities of biotin-functionalized, non-biofouling pOEGMA brushes, synthesized by surface-initiated polymerization from mixed SAMs with different mole fractions of the polymerization initiator on gold surfaces.

Surface-initiated, reversible polymerization from surface-tethered oligonucleotides by enzymatic processes.

Back and forth: Enzymatic, reversible polymerization on gold surfaces was efficiently carried out from surface-tethered self-priming oligodeoxynucleotides in a sequence-specific fashion by using two kinds of enzymes. Taq DNA polymerase, acting as a catalyst, facilitated DNA polymerization, and DNA restriction enzymes cut DNA polymers from the surface.