Kenichi Nagase

Thermoresponsive surfaces, prepared by grafting of poly(N-isopropylacrylamide) (PIPAAm) or its copolymers, have been investigated for biomedical applications. Thermoresponsive cell culture dishes that show controlled cell adhesion and detachment following external temperature changes, represent a promising application of thermoresponsive surfaces. These dishes can be used to fabricate cell sheets, which are currently used as effective therapies for patients. Thermoresponsive microcarriers for la

Temperature-responsive intelligent surfaces, prepared by the modification of an interface with poly(N-isopropylacrylamide) and its derivatives, have been used for biomedical applications. Such surfaces exhibit temperature-responsive hydrophilic/hydrophobic alterations with external temperature changes, which, in turn, result in thermally modulated interactions with biomolecules and cells. In this review, we focus on the application of these intelligent surfaces to chromatographic separation and

We have prepared various poly(N-isopropylacrylamide) (PIPAAm)-grafted silica bead surfaces through surface-initiated atom transfer radical polymerization (ATRP) by changing graft densities and brush chain lengths. The prepared surfaces were characterized by chromatographic analysis using the modified silica beads as chromatographic stationary phases. ATRP initiator (2-(m,p-chloromethylphenyl)ethyltrichlorosilane) density on silica bead surfaces was modulated by changing the feed composition of t

Dense poly(N-isopropylacrylamide) (PIPAAm) brushes were created on silica bead surfaces by surface-initiated atom transfer radical polymerization (ATRP). Interfacial properties of PIPAAm brushes were characterized by thermoresponisve interaction with biomolecules. The grafted amounts of PIPAAm on silica bead surfaces exceeded that from previously reported polymer-hydrogel-modified silica beads prepared by conventional radical polymerization by nearly 1 order of magnitude. Temperature-dependent c

We have prepared poly( N-isopropylacrylamide (IPAAm)- co-2-(dimethylamino)ethylmethacrylate (DMAEMA)) brush-grafted silica bead surfaces through surface-initiated atom transfer radical polymerization (ATRP) using the CuCl/CuCl 2/Me 6TREN catalytic system in 2-propanol at 25 degrees C for 16 h. The prepared temperature-responsive surfaces were characterized by chromatographic analysis using the modified silica beads as stationary phases. Chromatographic retention times for adenosine nucleotides i

Many bioactive compounds, pharmaceutical proteins, and therapeutic cells are used in medical treatments. Methods for the effective purification of such compounds that retain their activities are greatly needed. This review article describes various types of materials based on thermoresponsive polymers for bioanalysis and bioseparations, e.g., thermoresponsive chromatography and thermally modulated cell separation. Poly(N-isopropylacrylamide) (PIPAAm) and its derivatives show temperature-dependen

PIPAAm-brush grafted glass substrates with various graft densities and chain lengths were prepared via surface-initiated ATRP. Temperature-dependent physicochemical properties of the surfaces were characterized by means of ATR/FT-IR spectroscopy, XPS, AFM, and contact angle measurements. ATRP conditions influence the amount of grafted PIPAAm and the surface wettability and roughness of the substrate. Fibronectin adsorption and EC adhesion increased with decreasing density of PIPAAm brushes. EC a

Poly(N-isopropylacrylamide) (PNIPAAm) is the most well-known and widely used stimuli-responsive polymer in the biomedical field owing to its ability to undergo temperature-dependent hydration and dehydration with temperature variations, causing hydrophilic and hydrophobic alterations. This temperature-dependent property of PNIPAAm provides functionality to interfaces containing PNIPAAm. Notably, the hydrophilic and hydrophobic alterations caused by the change in the temperature-responsive proper

Thermoresponsive, cationic, copolymer brushes poly(N-isopropylacrylamide(IPAAm)-co-N,N-dimethylaminopropylacrylamide-co-N-tert-butylacrylamide(tBAAm)) and poly(IPAAm-co-3-acrylamidopropyl trimethylammonium chloride-co-tBAAm) were prepared on glass substrates through surface-initiated atom transfer radical polymerization. Prepared copolymer brushes were investigated as thermally modulated cell separation materials. Densely packed cationic copolymer brushes were formed on the glass substrates, and

Poly(N-isopropylacrylamide) (PIPAAm) brush grafted glass surfaces with various brush lengths were prepared as cell separating intelligent interfaces through a surface-initiated atom transfer radical polymerization (ATRP) with a CuCl–Me6TREN catalytic system and α-chloro-p-xylene as a free initiator in 2-propanol at 25 °C for 16 h. Characterization of the prepared surface was performed by X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR/FT-IR) sp

We have prepared poly( N-isopropylacrylamide) (PIPAAm) brush-grafted surfaces with varied temperature-responsive hydrophobic properties through surface-initiated atom transfer radical polymerization (ATRP). These temperature-responsive surfaces were characterized by chromatographic analysis using modified silica beads as a chromatographic stationary phase in aqueous mobile phase. Mixed silane self-assembled monolayers (SAMs) comprising ATRP initiator and silanes with various terminal functional

Thermo-responsive chromatography matrices with three types of graft architecture were prepared, and their separation performance and stability for continuous use were investigated. Poly(N-isopropylacrylamide)(PIPAAm) hydrogel-modified silica beads were prepared by a radical polymerization through modified 4,4'-azobis(4-cyanovaleric acid) and N,N'-methylenebisacrylamide. Dense PIPAAm brush-grafted silica beads and dense poly(N-tert-Butylacrylamide (tBAAm)-b-IPAAm) brush-grafted silica beads were

Small interfering RNAs (siRNAs) have been attracting significant attention owing to their gene silencing properties, which can be utilized to treat intractable diseases. In this study, two temperature-responsive liposomal siRNA carriers were prepared by modifying liposomes with different polymers-poly(<i>N</i>-isopropylacrylamide-<i>co</i>-<i>N</i>,<i>N</i>-dimethylaminopropyl acrylamide) (P(NIPAAm-<i>co</i>-DMAPAAm)) and poly(<i>N</i>-isopropylacrylamide-<i>co</i>-<i>N</i>,<i>N</i>-dimethylacry