Biological Stimuli-Induced Phase Transition of a Synthesized Block Copolymer: Preferential Interactions between PNIPAM-b-PNVCL and Heme Proteins

Abstract

The beguiling world of functional polymers is dominated by thermoresponsive polymers with unique structural and molecular attributes. Limited work has been reported on the protein-induced conformational transition of block copolymers; furthermore, the literature lacks a clear understanding of the influence of proteins on the phase behavior of thermoresponsive copolymers. Herein, we have synthesized poly(N-isopropylacrylamide)-b-poly(N-vinylcaprolactam) (PNIPAM-b-PNVCL) by RAFT polymerization using N-isopropylacrylamide and N-vinylcaprolactam. Furthermore, using various biophysical techniques, we have explored the effect of cytochrome c (Cyt c), myoglobin (Mb), and hemoglobin (Hb) with varying concentrations on the aggregation behavior of PNIPAM-b-PNVCL. Absorption and steady-state fluorescence spectroscopy measurements were performed at room temperature to examine the copolymerization effect on fluorescent probe binding and biomolecular interactions between PNIPAMb-PNVCL and proteins. Furthermore, temperature-dependent fluorescence spectroscopy and dynamic light scattering studies were performed to get deeper insights into the lower critical solution temperature (LCST) of PNIPAM-b-PNVCL. Small-angle neutron scattering (SANS) was also employed to understand the copolymer behavior in the presence of heme proteins. With the incorporation of proteins to PNIPAM-b-PNVCL aqueous solution, LCST has been varied to different extents owing to the preferential, molecular, and noncovalent interactions between PNIPAM-b-PNVCL and proteins. The present study can pave new insights between heme proteins and block copolymer interactions, which will help design biomimetic surfaces and aid in the strategic fabrication of copolymer−protein bioconjugates.

Tweaking Behavior of Hydrogen Bond Donor in Choline Chloride-Based Deep Eutectic Solvents for Regulating the Phase Transition of Poly(N-vinylcaprolactam): A Sustainable Medium for an Early Hydrophobic Collapse

“…Poly­( N -vinylcaprolactam) (PVCL) has received significant attention due to its characteristic features and diversified applications in biomedical science and pharmaceutical industries. − Owing to its tremendous sensitivity and biocompatibility, PVCL-based “smart” materials such as nanohybrids, microgels, hydrogels, and copolymers have been widely used in various applications. ,− PVCL can respond to different stimulants, such as proteins, temperature, ionic strength, and osmolytes. − Deep eutectic solvents (DESs) are an emerging class of benign liquid formulations that have gained popularity owing to idiosyncratic properties that outperform traditional ionic liquids (ILs). − High solubilization power, solventless preparation, low volatility, good stability, cost effectiveness, and wider availability are some of the properties of DESs that make them an ingenious and perfect solvent alternative. − The DESs consist of hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) groups.…”

Injectable bottlebrush hydrogels with tissue-mimetic mechanical properties

“…3C ) and consistent with theoretical predictions ( 40 , 41 , 48 ). The proposed system benefits from PNIPAM’s distinct LCST transition within the physiological temperature range ( 49 ) yet readily allows application of other thermosensitive polymers such as poly( N -vinyl caprolactam) and polyoxazolines ( 45 , 50 ). Strong microphase separation upon temperature stimuli yields soft yet mechanically robust hydrogels that maintain their shape upon extrusion ( Fig.…”

Large three-dimensional cell constructs for tissue engineering

“…The hydrophilicity of a thermo-responsive polymer changes according to the temperature. For example, poly- N -isopropylacrylamide (pNIPAAm), which has a low critical solution temperature (LCST) [ 40 , 41 ], was used for preparing two-dimensional (2D) cell aggregates, referred to as cell sheets [ 42 , 43 ]. We hypothesized that if the cell sheet was formed on the pNIPAAm-coated 2D surface, scaffold-free 3D cell constructs comprised only cells that could be fabricated using 3D-rendered pNIPAAm.…”