Specific noncovalent interactions that are indicative of attractive, directional intermolecular forces have always been of key interest to medicinal chemists in their search for the "glue" that holds drugs and their targets together. With the rapid increase in the number of solved biomolecular structures as well as the performance enhancement of computer hardware and software in recent years, it is now possible to give more comprehensive insight into the geometrical characteristics and energetic landscape of certain sophisticated noncovalent interactions present at the binding interface of protein receptors and small ligands based on accumulated knowledge gaining from the combination of two quite disparate but complementary approaches: crystallographic data analysis and quantum-mechanical ab initio calculation. In this perspective, we survey massive body of published works relating to structural characterization and theoretical investigation of three kinds of strong, specific, direct, enthalpy-driven intermolecular forces, including hydrogen bond, halogen bond and salt bridge, involved in the formation of protein-ligand complex architecture in order to characterize their biological functions in conferring affinity and specificity for ligand recognition by host protein. In particular, the biomedical implications of raised knowledge are discussed with respect to potential applications in rational drug design.

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Owing to the unique combination of electrical conductivity and tissue-like mechanical properties, conducting polymer hydrogels have emerged as a promising candidate for bioelectronic interfacing with biological systems. However, despite the recent advances, the development of hydrogels with both excellent electrical and mechanical properties in physiological environments remains a lingering challenge. Here, we report a bi-continuous conducting polymer hydrogel (BC-CPH) that simultaneously achieves high electrical conductivity (over 11 S cm-1), stretchability (over 400%) and fracture toughness (over 3,300 J m-2) in physiological environments, and is readily applicable to advanced fabrication methods including 3D printing. Enabled by the BC-CPH, we further demonstrate multi-material 3D printing of monolithic all-hydrogel bioelectronic interfaces for long-term electrophysiological recording and stimulation of various organs. This study may offer promising materials and a platform for future bioelectronic interfacing.

Deregulation of the receptor tyrosine kinase mesenchymal epithelial transition factor (MET) has been implicated in several human cancers and is an attractive target for small molecule drug discovery. Herein, a series of 6,7-disubstituted-4-phenoxyquinoline derivatives bearing pyridazinone derivatives were designed, synthesized and evaluated for their enzymatic inhibitory activity against c-Met kinase and cellular potency against A549, HepG2, and MCF-7 cell lines. Eight of them are equal to more active than positive control Foretinib against one or more cell lines and enzyme. The most promising compound 53 showed superior activity to Foretinib, which possessed excellent c-Met kinase inhibition on a singledigital nanomolar level (IC50 = 0.6 nM), and cancer cells of A549 (IC50 = 0.003 µM), HepG2 (IC50 = 0.49 µM) and MCF-7 cells (IC50 = 0.006 µM). The result of AO single staining indicated that compound 53 could induce remarkable apoptosis of HepG2 cell.

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Stretchable, adhesive, and conductive hydrogels have been regarded as ideal interfacial materials for seamless and biocompatible integration with the human body. However, existing hydrogels can rarely achieve good mechanical, electrical, and adhesive properties simultaneously, as well as limited patterning/manufacturing techniques posing severe challenges to bioelectronic research and their practical applications. Herein, we develop a stretchable, adhesive, and conductive Ti3C2Tx-polyacrylic acid hydrogel by a simple pre-crosslinking method followed by successive direct ink writing 3D printing. Pre-polymerization of acrylic acid can be initiated by mechanical mixing with Ti3C2Tx nanosheet suspension, leading to the formation of viscous 3D printable ink. Secondary free radical polymerization of the ink patterns via 3D printing can achieve a stretchable, adhesive, and conductive Ti3C2Tx-polyacrylic acid hydrogel. The as-formed hydrogel exhibits remarkable stretchability (~622%), high electrical conductivity (5.13 S m−1), and good adhesion strength on varying substrates. We further demonstrate the capability of facilely printing such hydrogels into complex geometries like mesh and rhombus patterns with high resolution and robust integration.

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-based hydrogels have emerged as ideal interfacing materials for bioelectronics because of their intriguing electrical, mechanical, and biological properties. However, the development of high-performance PEDOT:PSS-based hydrogels simultaneously achieving high conductivity, robust mechanical properties, and accessibility for advanced manufacturing technologies remains a critical challenge for further advancing such materials toward practical applications. Herein, we develop a highly conductive, intrinsically soft, tough yet stretchable PEDOT:PSS-based hydrogel via a simple PSS-chain engineering strategy of introducing thermally cross-linkable N-(hydroxymethyl)acrylamide segments. The resultant PEDOT:PSS hydrogel exhibits high electrical conductivity (1850 S m–1), high stretchability (>50%), low Young’s modulus (4 MPa), and superior toughness (400 kJ m–3), satisfying multiple property requirements for practical bioelectronic applications. Based on this material, we further develop a novel PEDOT:PSS ink with superior 3D printability for direct ink writing 3D printing, enabling us to facilely fabricate bioelectronic devices like soft skin electrodes comparable to commercial products via multi-material 3D printing.

Supercapacitors are widely used in various fields due to their high power density, fast charging and discharging speeds, and long service life. However, with the increasing demand for flexible electronics, integrated supercapacitors in devices are also facing more challenges, such as extensibility, bending stability, and operability. Despite many reports on stretchable supercapacitors, challenges still exist in their preparation process, which involves multiple steps. Therefore, we prepared stretchable conducting polymer electrodes by depositing thiophene and 3-methylthiophene on patterned 304 stainless steel (SS 304) through electropolymerization. The cycling stability of the prepared stretchable electrodes could be further improved by protecting them with poly(vinyl alcohol)/sulfuric acid (PVA/H2SO4) gel electrolyte. Specifically, the mechanical stability of the polythiophene (PTh) electrode was improved by 2.5%, and the stability of the poly(3-methylthiophene (P3MeT) electrode was improved by 7.0%. As a result, the assembled flexible supercapacitors maintained 93% of their stability even after 10,000 cycles of strain at 100%, which indicates potential applications in flexible electronics.