Biocompatible hydrogel coating on single living cells through visible light-induced polymerization.

Visible light-mediated photocatalysis leads to the efficient hydrogel coating of individual mammalian cells, functionalized with biocompatible anchor molecules tagged with fluorescein serving as a trifecta: photocatalyst, initiator, and fluorophore. NIH3T3 fibroblast cells are encapsulated within hydrogel shells of poly(ethylene glycol) diacrylate (PEGDA) and -vinylpyrrolidone without any noticeable decrease in cell viability.

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.

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.

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) (OEGMA), and poly(2-hydroxyethyl metacharylate) (HEMA) on microscopic glass surfaces. As a result, the non-biofouling performances increased in this order: agarose < OEGMA < HEMA, and the binding capabilities increased in this order: HEMA < OEGMA < 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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

Systematic study of fluorescein-functionalized macrophotoinitiators for colorimetric bioassays.

We report a systematic investigation of a set of photoreducible macrophotoinitiators for use in polymerization-based signal amplification. To test the dependence of photopolymerization responses on the number of photoinitiators localized per molecular recognition event, we gradually increased the number of photoinitiator molecules coupled to a constant scaffold macromolecule from an average of 7 per polymer to an average of 168 per polymer. To evaluate the capacity of the macrophotoinitiators to detect molecular recognition, we coupled neutravidin to these molecules to recognize biotin-labeled DNA immobilized on biochip test surfaces.

In situ hetero end-functionalized polythiophene and subsequent "click" chemistry with DNA.

It is demonstrated that bifunctionalized polythiophenes involving thiol and azide end-functional groups can be synthesized by chain-growth Suzuki-Miyaura type polymerization. The bifunctionalized polythiophenes are successfully characterized by 1H NMR, gel permeation chromatography (GPC), and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). Furthermore, the azide end-group reacts with DNA via "click chemistry" to form a polythiophene/DNA hybrid structure, which is characterized by ESI-MS.

Syntheses of organic molecule-DNA hybrid structures.

Investigation of robust and efficient pathways to build DNA-organic molecule hybrid structures is fundamentally important to realize controlled placement of single molecules for potential applications, such as single-molecule electronic devices. Herein, we report a systematic investigation of synthetic processes for preparing organic molecule-DNA building blocks and their subsequent elongation to generate precise micrometer-sized structures. Specifically, optimal cross-coupling routes were identified to enable chemical linkages between three different organic molecules, namely, polyethylene glycol (PEG), poly(p-phenylene ethynylene) (PPE), and benzenetricarboxylate, with single-stranded (ss) DNA.

The shear flow processing of controlled DNA tethering and stretching for organic molecular electronics.

DNA has been recently explored as a powerful tool for developing molecular scaffolds for making reproducible and reliable metal contacts to single organic semiconducting molecules. A critical step in the process of exploiting DNA-organic molecule-DNA (DOD) array structures is the controlled tethering and stretching of DNA molecules. Here we report the development of reproducible surface chemistry for tethering DNA molecules at tunable density and demonstrate shear flow processing as a rationally controlled approach for stretching/aligning DNA molecules of various lengths.