Thermoresponsive copolymer nanofilms for controlling cell adhesion, growth, and detachment.
ABSTRACT This study reports the development and use of a novel thermoresponsive polymeric nanofilm for controlling cell adhesion and growth at 37 °C, and then cell detachment for cell recovery by subsequent temperature drop to the ambient temperature, without enzymatic cleavage or mechanical scraping. A copolymer, poly(N-isopropylacrylamide-co-hydroxypropyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (abbreviated PNIPAAm copolymer), was synthesized by free radical polymerization. The thermoresponses of the copolymer in aqueous solution were demonstrated by dynamic light scattering (DLS) through detecting the sensitive changes of copolymer aggregation against temperature. The DLS measurements revealed the lower critical solution temperature (LCST) at approximately 30 °C. The PNIPAAm film stability and robustness was provided through silyl cross-linking within the film and with the hydroxyl groups on the substrate surface. Film thickness, stability, and reversibility with respect to temperature switches were examined by spectroscopic ellipsometry (SE), atomic force microscopy (AFM), and contact angle measurements. The results confirmed the high extent of thermosensitivity and structural restoration based on the alterations of film thickness and surface wettability. The effective control of adhesion, growth, and detachment of HeLa and HEK293 cells demonstrated the physical controllability and cellular compatibility of the copolymer nanofilms. These PNIPAAm copolymer nanofilms could open up a convenient interfacial mediation for cell film production and cell expansion by nonenzymatic and nonmechanical cell recovery.
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ABSTRACT: Two types of thermoresponsive microgels, poly(N-isopropylacrylamide) (PNIPAM) microgels and poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAMAC) microgels were synthesized and used as templates for the mineralization of amorphous calcium carbonate (ACC) by diffusion of CO(2) vapor under ambient conditions. Thermosensitive PNIPAM/CaCO(3) hybrid macroscopic hydrogels and micrometer-sized PNIPAMAC/CaCO(3) hybrid microgels were controllably obtained and different mineralization mechanistic processes were proposed. The impact of the loaded CaCO(3) on the size, morphology, stability, and thermosensitivity of the microgels was also analyzed. PNIPAM/CaCO(3) hybrid macrogels had a slight decrease in thermoresponsive phase transition temperature, while PNIPAMAC/CaCO(3) hybrid microgels showed a clear increase in phase transition temperature. The difference reflected different amount and location of ACC in the gel network, causing different interactions with polymer chains. The PNIPAMAC/CaCO(3) microgels formed stable monolayer films on bare silica wafers and glass coverslips upon drying. The microgel films could facilitate the attachment and growth of 3T3 fibroblast cells and their subsequent detachment upon temperature drop from 37 °C to the ambient condition around 20 °C, thus, offering a convenient procedure for cell harvesting.Biomacromolecules 06/2012; 13(8):2299-308. · 5.79 Impact Factor
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ABSTRACT: Rare cells already have become established indicators for disease diagnosis, to help track prognosis, and in developing personalized therapy. Numerous techniques have been developed to effectively and specifically detect and sort rare cells and cell isolation techniques have gained much attention among researchers in last few decades. Recent developments in nanotechnologies and microfluidics have been used with great promise towards these goals. The research emphasis has also shifted from simple detection with microfluidic devices to comprehensive isolation, collection and subsequent analysis with integrated and automated systems. The first challenge in post-isolation analysis is cell detachment from substrates, while keeping cells viable and unperturbed. In this review, various methods used for cell detachments are discussed. For effective cell sorting, the detachment is identified as critical criteria for selecting substrates and methods.Biotechnology advances 08/2013; · 8.91 Impact Factor
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ABSTRACT: A novel copolymer, poly(N-isopropylacrylamide-co-hydroxypropyl methacrylate-co-3-trimethoxysilypropyl methacrylate) has been synthesized and the hydrodynamic diameters in various aqueous solutions under different temperatures are determined by dynamic light scattering. The results show that the hydrodynamic diameters of copolymers have no obvious change in each working solution below lower critical solution temperature (LCST); across LCST, the diameters increased suddenly at different initial temperature in various aqueous solutions; above LCST, they decreased slightly as the temperature increased in UHQ water, and increased continuously with increasing temperature or salt concentration in saline solutions, and reduced with the rising of pH value in pH buffer. These are attributed to different intermolecular and intramolecular forces leading to disparity in dimension, conformation, and LCST of copolymers. The hydrogen bonding between water molecules and copolymer chains could maintain size and conformation of copolymer single chain; the hydrogen bonding between amide linkages and hydrophobic interactions between isopropyl groups result in intramolecular collapse and intermolecular aggregation; the electrostatic repulsion weakens aggregation extent of copolymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013Journal of Applied Polymer Science 03/2013; 127(6). · 1.40 Impact Factor