Jun-ichi Anzai’s research while affiliated with Tohoku University and other places

The capability to encapsulate designated live cells into a biologically and mechanically tunable polymer layer is in high demand. Here, an approach to weave functional DNA polymer cocoons has been proposed as an encapsulation method. By developing in situ DNA-oriented polymerization (isDOP), we demonstrate a localized, programmable, and biocompatible encapsulation approach to graft DNA polymers onto live cells. Further guided by two mutually aided enzymatic reactions, the grafted DNA polymers are assembled into DNA polymer cocoons at the cell surface. Therefore, the coating of bacteria, yeast, and mammalian cells has been achieved. The capabilities of this approach may offer significant opportunities to engineer cell surfaces and enable the precise manipulation of the encapsulated cells, such as encoding, handling, and sorting, for many biomedical applications.

This review provides an overview of the synthesis of layer-by-layer (LbL) assemblies containing calix[n]arene (CA[n]) and cucurbit[n]uril (CB[n]) and their applications. LbL assemblies, such as thin films and microcapsules, containing selective binding sites have attracted considerable attention because of their potential use in separation and purification, sensors for ions and molecules, and controlled release. CA[n]-containing LbL films have been prepared using sulfonated CA[n] and cationic polymers to construct chemical sensors and molecular containers. CA[n]-containing LbL films deposited on the surface of a porous support are useful as ion-selective membranes that exhibit selective permeability to monovalent ions over multivalent ions. CB[n]s have been used as molecular glues for the construction of LbL films and microcapsules by taking advantage of the strong affinity of CB[n]s to aromatic compounds. CB[n]s form a stable 1:1:1 ternary complex with electron-rich and electron-deficient molecules in LbL films to stabilize the assemblies. CB[n]-containing LbL films can also be deposited on the surfaces of micro templates and nanopore membranes to construct microcapsules for controlled release and nanochannels for selective ion transport, respectively.

Alizarin red S (ARS) was confined in layer-by-layer (LbL) films composed of phenylboronic acid-modified poly(ethyleneimine) (PBA-PEI) and carboxymethylcellulose (CMC) to study the voltammetric response to diol and polyol compounds. The LbL film-coated gold (Au) electrode and quartz slide were immersed in an ARS solution to uptake ARS into the film. UV-visible absorption spectra of ARS-confined LbL film suggested that ARS formed boronate ester (ARS-PBS) in the film. The cyclic voltammetry of the ARS-confined LbL film-coated electrodes exhibited oxidation peaks at −0.50 and −0.62 V, which were ascribed to the oxidation reactions of ARS-PBS and free ARS, respectively, in the LbL film. The peak current at −0.62 V increased upon the addition of diol or polyol compounds such as L-dopa, glucose, and sorbitol into the solution, depending on the concentration, whereas the peak current at −0.50 V decreased. The results suggest a possible use of ARS-confined PBA-PEI/CMC LbL film-coated Au electrodes for the construction of voltammetric sensors for diol and polyol compounds.

This review provides an overview of the syntheses of photosensitive layer-by-layer (LbL) films and microcapsules modified with azobenzene derivatives and their biomedical applications. Photosensitive LbL films and microcapsules can be prepared by alternate deposition of azobenzene-bearing polymers and counter polymers on the surface of flat substrates and microparticles, respectively. Azobenzene residues in the films and microcapsules exhibit trans-to-cis photoisomerization under UV light, which causes changes in the physical or chemical properties of the LbL assemblies. Therefore, azobenzene-functionalized LbL films and microcapsules have been used for the construction of photosensitive biomedical devices. For instance, cell adhesion on the surface of a solid can be controlled by UV light irradiation by coating the surface with azobenzene-containing LbL films. In another example, the ion permeability of porous materials coated with LbL films can be regulated by UV light irradiation. Furthermore, azobenzene-containing LbL films and microcapsules have been used as carriers for drug delivery systems sensitive to light. UV light irradiation triggers permeability changes in the LbL films and/or decomposition of the microcapsules, which results in the release of encapsulated drugs and proteins.

Quantitation of plasma membrane proteins (PMPs) are fundamental and frequently performed in the daily lab-work. However, challenged by inherent/interacted hetero-structures and complex surroundings of the PMPs in lipid membrane, quantitative techniques for PMP often require complex treatments (e.g. labelling, isolation, purification, and determination), and the sensitivity is usually not satisfactory. To address the problem, we have proposed a novel method that enables quantitation of PMPs with extremely high sensitivity, in an easier-to-manipulate and more streamlined way. This method is based on the design of in situ rolling cycling replication-templated amplification strategy, named as isRTA. In fact, two rounds of DNA cascade isothermal amplifications have been conducted. The 1st round of amplification reaction can provide templates for the 2nd round of amplification, thus significant enhancement of quantitative signals can be achieved. In this way, PMPs are quantified with ultra-high sensitivity, as few as 25 copies of PMPs can be detected per cell. Moreover, the advantages of isRTA have been demonstrated by simultaneous identification of several PMP biomarkers (MUC1, EpCAM and HER2) that are expressed with wide distribution range on breast cancer cells. The precise typing of breast cancer cell subsets is thus possible based on “quantitative-to-qualitative” strategy. Therefore, the unprecedented sensitivity and high usability of isRTA method may give significant prospects for delving into membrane proteins and their related bio-functions in many research fields.

A phenylboronic acid (PBA)/polyvinyl alcohol (PVA) dispersion was prepared by mixing PBA and PVA solutions. The PVA/PBA conjugate precipitated due to binding of several PBAs to PVA and reduction of solubility. The formation of the PVA/PBA dispersion was affected by the ratio of PBA to PVA, the ionic strength, and the pH. The aim of this study was to investigate the sugar and H2O2 response of the dispersion. The optical density (OD) of the PVA/PBA dispersion decreased by addition of fructose, which replaced PVA in the boronate ester by competitive interaction. The PVA/PBA dispersion was also dissolved by addition of H2O2, because the boronate ester bond was cleaved by the oxidative reaction of H2O2. The PVA/PBA dispersion completely dissolved in 10 mM fructose and 3.0 mM H2O2. In addition, the PVA/PBA dispersion responded to 10 mM glucose under glucose oxidase containing conditions. Functional PBA material was prepared by simple operation.

Multilayer films that decompose in the presence of lactate were prepared by depositing phenylboronic acid-modified poly(allylamine) (PBA-PAH) and poly(vinyl alcohol) (PVA) on a lactate oxidase (LOx) layer. The layers adhered through boronate ester bonds. The resulting LOx(PBA-AH/PVA)10 film was stable in pH 7.4 solution but decomposed following the addition of lactate. The carbon-boron bonds in PBA residues were cleaved by oxidative reaction with H2O2 produced by the enzymatic reaction of LOx. Approximately 90% of the film decomposed following exposure for 120 and 30min to 0.05 and 20mM lactate at pH 7.4, respectively. The multilayer film therefore decomposed under conditions comparable to the extracellular environment of tumors (20mM lactate at pH 6.5). Our results show that LOx/(PBA-PAH/PVA)10 multilayer film could be used for cancer drug delivery systems.

This article reviews the synthesis and applications of cyclodextrin (CD)-containing layer-by-layer (LbL) films and microcapsules. CD-containing LbL films and microcapsules have been synthesized through the electrostatic interactions between charged CDs and polyelectrolytes or the formation of host–guest complexes. In the former strategy, sulfonated and carboxylated CDs are often combined with oppositely charged polyelectrolytes. In contrast, in the latter strategy, CD-bearing polymers and guest-modified polymers are used as components of LbL assembly. Typical guest molecules include adamantane, ferrocene, and azobenzene derivatives. Electrochemical biosensors have been constructed by coating the surface of electrodes with CD-containing LbL films. In addition, CD-containing LbL assemblies are used as scaffolds for constructing drug delivery systems, in which hydrophobic, poorly soluble drugs are loaded on the film through host–guest complexation.

This article reviews recent progress in the development of nanomaterial-based electrochemical biosensors for cancer biomarkers. Because of their high electrical conductivity, high affinity to biomolecules, and high surface area-to-weight ratios, nanomaterials, including metal nanoparticles, carbon nanotubes, and graphene, have been used for fabricating electrochemical biosensors. Electrodes are often coated with nanomaterials to increase the effective surface area of the electrodes and immobilize a large number of biomolecules such as enzymes and antibodies. Alternatively, nanomaterials are used as signaling labels for increasing the output signals of cancer biomarker sensors, in which nanomaterials are conjugated with secondary antibodies and redox compounds. According to this strategy, a variety of biosensors have been developed for detecting cancer biomarkers. Recent studies show that using nanomaterials is highly advantageous in preparing high-performance biosensors for detecting lower levels of cancer biomarkers. This review focuses mainly on the protocols for using nanomaterials to construct cancer biomarker sensors and the performance characteristics of the sensors. Recent trends in the development of cancer biomarker sensors are discussed according to the nanomaterials used.