Characterization of poly(N-isopropylacrylamide)–nucleobase supramolecular complexes featuring bio-multiple hydrogen bonds

Abstract

In this study we employed poly(N-isopropylacrylamide) (PNIPAAm) as a matrix that we hybridized with five different nucleobase units (adenine, thymine, uracil, guanine, cytosine) to generate PNIPAAm-nucleobase supramolecular complexes (PNSCs) stabilized through bio-multiple hydrogen bonds (BMHBs). These nucleobase units interacted with PNIPAAm through BMHBs of various strengths, leading to competition between the BMHBs and the intramolecular hydrogen bonds (HBs) of PNIPAAm. The changes in morphology, crystalline structure, and thermoresponsive behavior of PNIPAAm were related to the strength of its BMHBs with the nucleobases. The strengths of the BMHBs followed the order guanine > adenine > thymine > cytosine > uracil, as verified through analyses of Fourier transform infrared spectra, lower critical solution temperatures, and inter-association equilibrium constants. The PNSCs also exhibited remarkable improvements in conductivity upon the formation of BMHBs, which facilitated proton transport. The neat PNIPAAm film was an insulator, but it transformed into a semiconductor after hybridizing with the nucleobases. In particular, the resistivity of the PNIPAAm-guanine supramolecular complex decreased to 1.35 × 10(5) ohm cm. The resistivity of the PNIPAAm-cytosine supramolecular complex increased significantly from 5.83 × 10(6) to 3 × 10(8) ohm cm upon increasing the temperature from 40 to 50 °C, suggesting that this material might have applicability in thermo-sensing. The ability to significantly improve the conductivity of hydrogels through such a simple approach involving BMHBs might facilitate their use as novel materials in bioelectronics.

Thermo-Tunable Pores and Antibiotic Gating Properties of Bovine Skin Gelatin Gels Prepared with Poly(n-isopropylacrylamide) Network

“…In the spectrum of NG0, the absorption band around 3464 cm −1 became broader, indicating hydrogen bond formation between the –OH and –NHCO groups. Moreover, the bands at 1670 and 1597 cm −1 in the spectrum of PNIPAAm shifted to 1658 and 1558 cm −1 , respectively, in the spectrum of NG0, indicating hydrogen bonding interactions between bovine skin gelatin and PNIPAAm [ 39 ]. This information proved that PNIPAAm and bovine skin gelatin were highly miscible with each other.…”

Identification of DNA single-base mismatches by resistivity of poly(N-isopropylacrylamide)-block-ssDNA copolymer brush films at dual temperatures

“…f Roughness (Ra) was obtained from AFM. BMHBs can improve H + transport in PNIPAAm-b-ssDNA copolymer brushes, 18,19 so we focused mainly on determining the temperature-responsive resistance of our functionalized surfaces. The linear I-V curves exhibited ohmic behavior at 25 and 80 C during device use (Scheme 2).…”

“…17 Researchers have also shown that DNA block copolymers can be assembled into various morphologies by utilizing the molecular recognition property of DNA. 18,19 Gianneschi and co-workers synthesized a DNA brush copolymer that undergoes a reversible sphere-to-cylinder morphology change by DNA cleavage and hybridization. 20 Herrmann et al reported the formation of rodlike assemblies of DNA-block-poly(propylene oxide) (DNA-b-PPO) using a long repetitive complementary DNA strand as a template.…”

Adenine Derivatives for Regenerable Antibacterial Surface Applications Based on A−T Base Pairing

“…[15] Recently, self-assembly conjugation in polymer chemistry has become increasingly prominent in the produc-tion of smart materials due to its advantage of being stimuliresponsive with reversible interactions. [16,17] In our previous work, purine derivatives that had a tetrazole ring showed DNA damage and higher antibacterial activities compared to cyano compounds. [18] Tetrazoles, a well-described class of nitrogen-containing heterocycles, have shown valuable properties with a wide range of applications in materials science and beyond, including catalysis, propellants, information recording systems, explosives, and with possible applications in high-energy chemistry.…”