Adamantane Research Articles

Optimising Electrical Interfacing between the Trimeric Copper Nitrite Reductase and Carbon Nanotubes.

The immobilization of copper-containing nitrite reductase (NiR) from Alcaligenes faecalis on functionalised multi-walled carbon nanotube (MWCNT) electrodes is reported. It is demonstrated that this immobilization is mainly driven by hydrophobic interactions, promoted by the modification of MWCNTs with adamantyl groups. Direct electrochemistry shows high bioelectrochemical reduction of nitrite at the redox potential of NiR with high current density of 1.41 mA cm-2 . Furthermore, the desymmetrization of the trimer upon immobilization induces an independent electrocatalytic behavior for each of the three enzyme subunits, corroborated by an electron-tunneling distance dependence.

Zr6(μ3‐O)4(μ3‐OH)4](1‐adamantanecarboxylate)12]: a model for extrinsic “defect‐engineerable” porosity

AbstractThe molecular zirconium‐oxo cluster with 1‐adamantanecarboxylate of ideal formula [Zr6O4(OH)4(AdCA)12] (AdCA=1‐adamantanecarboxylate) has a near spherical shape with a hydrophobic “shell” of bulky rigid adamantyl groups. The use of formic acid as a modulator and a large excess of the HAdCA were found to be crucial for its reproducible synthesis and the formation of ~100‐150 μm well‐formed rhombohedral single crystals. Crystallization in the presence of formic acid leads, however, to ligand‐substitution defects (1‐2 out of 12) which were quantified by thermogravimetry and NMR. A defect‐engineering with a higher defect ratio in such oxo clusters is a promising approach aiming at extrinsic porosity.

Syntheses of 25-Adamantyl-25-alkyl-2-methylidene-1α,25-dihydroxyvitamin D3 Derivatives with Structure-Function Studies of Antagonistic and Agonistic Active Vitamin D Analogs.

The active form of vitamin D3, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], is a major regulator of calcium homeostasis through activation of the vitamin D receptor (VDR). We have previously synthesized vitamin D derivatives with large adamantane (AD) rings at position 24, 25, or 26 of the side chain to study VDR agonist and/or antagonist properties. One of them-ADTK1, with an AD ring and 23,24-triple bond-shows a high VDR affinity and cell-selective VDR activity. In this study, we synthesized novel vitamin D derivatives (ADKM1-6) with an alkyl group substituted at position 25 of ADTK1 to develop more cell-selective VDR ligands. ADKM2, ADKM4, and ADKM6 had VDR transcriptional activity comparable to 1,25(OH)2D3 and ADTK1, although their VDR affinities were weaker. Interestingly, ADKM2 has selective VDR activity in kidney- and skin-derived cells-a unique phenotype that differs from ADTK1. Furthermore, ADKM2, ADKM4, and ADKM6 induced osteoblast differentiation in human dedifferentiated fat cells more effectively than ADTK1. The development of vitamin D derivatives with bulky modifications such as AD at position 24, 25, or 26 of the side chain is useful for increased stability and tissue selectivity in VDR-targeting therapy.

Electrochemiluminescence and electrochemical dual-mode detection of BACE1 activity based on the assembly of peptide and luminol co-functionalized silver nanoparticles induced by cucurbit[8]uril

A novel electrochemiluminescence (ECL) and electrochemical dual-mode sensor was developed for detecting the activity of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) and screening its inhibitor. Specifically, the adamantane (ADA)-functionalized peptide (P1), a designed substrate peptide for BACE1, was immobilized on the electrode surface via host-guest interaction between β-cyclodextrin (β-CD) and ADA. The aggregation of the peptide (P2) and luminol co-functionalized silver nanoparticles could be induced by cucurbit [8]uril (CB[8] due to the ability of CB[8] to accommodate two aromatic residues simultaneously. The obtained (CB[8]-P2-AgNPs-luminol)n aggregates with both ECL and electrochemical activity, used as the dual-mode signal probe, could be captured to the N-terminal of P1 through CB[8]. Once the substrate P1 was cleaved by BACE1, the probe-binding polypeptide fragment detached from the electrode surface, resulting in a remarkable decrease in the ECL and electrochemical signals. Taking advantage of the signal amplification function of the signal probe, the sensitive dual-mode assay for BACE1 activity can be achieved with the low detection limits of 33.11 pM for ECL and 53.19 pM for electrochemical mode. The superior analytical performance of this novel dual-mode sensor toward BACE1 activity suggested the promising application in early diagnosis of Alzheimer's disease (AD).

"Zombie" Macrophages for Targeted Drug Delivery to Treat Acute Pneumonia.

A cell-based drug delivery system has emerged as a promising drug delivery platform. Due to their innate inflammatory tropism, natural and engineered macrophages have exhibited targeted accumulation in inflammatory tissues, which has allowed targeted delivery of medicine for the treatment of a variety of inflammatory diseases. Nevertheless, live macrophages may take up the medicine and metabolize it during preparation, storage, and in vivo delivery, sometimes causing unsatisfactory therapeutic efficacy. In addition, live macrophage-based drug delivery systems are usually freshly prepared and injected, due to the poor stability that does not allow storage. "Off-the-shelf" products would be indeed conducive to the timely therapy of acute diseases. Herein, a cryo-shocked macrophage-based drug delivery system was developed via supramolecular conjugation of cyclodextrin (CD)-modified "zombie" macrophages and adamantane (ADA)-functionalized nanomedicine. "Zombie" macrophages exhibited a much better storage stability over time than their counterpart live macrophage drug carriers and maintained cell morphology, membrane integrity, and biological functions. In an acute pneumonia mouse model, "zombie" macrophages carried quercetin-loaded nanomedicine, hand-in-hand, to the inflammatory lung tissues and effectively alleviated the inflammation in mice.

Laccase immobilized in adamantane-modified PEGMA-based microgels: Tuning enzyme activity by beta-cyclodextrin

Intelligent immobilized enzymes can be constructed by designing “smart” carrier materials. In this study, we successfully prepared adamantane-modified PEGMA-based microgel-immobilized laccases (AdM-Lac) by precipitation polymerization in a laccase solution. AdM-Lac-DMCD was obtained by mixing 2,6-di-O-methyl-beta-cyclodextrin (DMCD) and AdM-Lac. By comparison, DLS, AFM, and IR results indicate that AdM-Lac exhibits DMCD-induced volume phase transition behavior. NMR analysis confirms the successful formation of inclusion complexes of DMCDs and adamantyl groups on AdM-Lac. The catalytic tests show that the enzyme activity of AdM-Lac-DMCD at 20 °C (24.09 U/L) is ca.70% higher than AdM-Lac (14.20 U/L). The Vmax value of AdM-Lac-DMCD (1.22 µM min−1) is similar to AdM-Lac (1.24 µM min−1), Whereas the Km value (52 µM) decreases by ca. 69%, even close to free laccase (41 µM), and the Vmax/Km ratio (0.0235 min−1) increases by about 2-fold. These results imply that DMCD initiates the volume swelling of AdM-Lac, resulting in increased enzyme activity and improved kinetic properties. Due to AdM-Lac having better storage stability, we suggest that laccase is stored as AdM-Lac, and applied as AdM-Lac-DMCD. This study successfully achieved the regulation of enzyme activity through the addition of molecules, providing a novel strategy for the design of “smart” carrier materials.

Proteinosomes via Self-Assembly of Thermoresponsive Miktoarm Polymer Protein Bioconjugates.

To fabricate nanoscale proteinosomes, thermoresponsive miktoarm polymer protein bioconjugates were prepared through highly efficient molecular recognition between the β-cyclodextrin modified BSA (CD-BSA) and the adamantyl group anchored at the junction point of the thermoresponsive block copolymer poly(ethylene glycol)-b-poly(di(ethylene glycol) methyl ether methacrylate) (PEG-b-PDEGMA). PEG-b-PDEGMA was synthesized by the Passerini reaction of benzaldehyde-modified PEG, 2-bromo-2-methylpropionic acid, and 1-isocyanoadamantane, followed by the atom transfer radical polymerization of DEGMA. Two block copolymers with different chain lengths of PDEGMA were prepared, and both self-assembled into polymersomes at a temperature above their lower critical solution temperatures (LCST). The two copolymers can undergo molecular recognition with the CD-BSA and form miktoarm star-like bioconjugates. The bioconjugates self-assembled into ∼160 nm proteinosomes at a temperature above their LCSTs, and the miktoarm star-like structure has a great effect on the formation of the proteinosomes. Most of the secondary structure and esterase activity of BSA in the proteinosomes were maintained. The proteinosomes exhibited low toxicity to the 4T1 cells and could deliver model drug doxorubicin into the 4T1 cells.

Conjugation of Macrophage-Mimetic Microalgae and Liposome for Antitumor Sonodynamic Immunotherapy via Hypoxia Alleviation and Autophagy Inhibition.

Sonodynamic therapy (SDT) is a noninvasive technique for local antitumor treatment; however, its clinical application is often limited by the low tumor accumulation of SDT agents, tumor's hypoxic microenvironment, and cytoprotective effects of autophagy. To address these issues, herein we developed surface-engineered chlorella (Chl, a green algae) as a targeted drug carrier and sustainable oxygen supplier (via photosynthesis) for significantly improved SDT via hypoxia alleviation as well as autophagy inhibition of chloroquine phosphate. In this design, the macrophage membrane was coated onto Chl to form macrophage-mimetic Chl (MChl) to increase its biocompatibility and targeted tumor accumulation driven by the inflammatory-homing effects of macrophage membranes. In addition, the membrane coating on Chl allowed lipid insertion to yield β-cyclodextrin (β-CD) modified MChl (CD-MChl). Subsequently, supramolecular conjugates of MChl-NP were constructed via host-guest interactions between CD-MChl and adamantane (ADA)-modified liposome (ADA-NP), and the anchored liposome went with CD-MChl hand-in-hand to the tumor tissues for co-delivery of Chl, hematoporphyrin, and chloroquine phosphate (loaded in ADA-NP). The synergistic therapy achieved via local oxygenation, SDT, and autophagy inhibition maximally improved the therapeutic efficacy of MChl-CQ-HP-NP against melanoma. Tumor rechallenging results revealed that the changes of tumor microenvironment including hypoxia alleviation, SDT induced immunogenic cell death, and autophagy inhibition collectively induced a strong antitumor immune response and memory.

Synthesis, crystal structure and antibacterial activity of zinc(II) complexes with Schiff bases derived from 5-fluorosalicylaldehyde

By a condensation of aliphatic amine containing adamantyl groups (amantadine, memantine, or 3-amino-1-adamantanol) and 5-fluorosalicylaldehyde, three new Schiff base ligands, HL1 – 3 , were synthesized. One Schiff base, zinc(II) chloride, and NaOH were stirred in anhydrous methanol generating three new zinc(II) complexes, C34H38F2N2O2Zn (1), C38H46F2N2O2Zn (2), and C34H38F2N2O4Zn (3), respectively. These complexes were characterized by melting point, elemental analysis, infrared spectrum, ultraviolet–visible spectrum, 1H NMR analysis, thermal analysis, and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis shows that 1 and 3 crystallize in the monoclinic system with space group P2 1 /c, but 2 crystallizes in the orthorhombic system with space group Pbca. Each asymmetric unit in 1 is composed of one zinc(II) and two deprotonated ligands; each asymmetric unit in 2 is constituted of one zinc(II), two deprotonated ligands as well as one dichloromethane. Each asymmetric unit in 3 is made up of one zinc(II), two deprotonated ligands, one methanol, and one lattice water. The central zinc(II) in 1–3 is four-coordinate via two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. The antibacterial activities of the three Schiff base ligands and the corresponding complexes against two gram positive bacteria, Staphylococcus aureus and Bacillus subtilis, and a gram negative bacteria, Escherichia coli, were tested.

Preparation, polymerization and properties of an adamantyl‐based benzoxazine

AbstractA novel adamantyl‐based benzoxazine (AD‐Bz) was successfully synthesized with 1,3‐bis(4‐aniline)‐adamantane (AD) derived from 1‐adamantanol and acetanilide through the Friedel–Crafts alkylation reaction. The chemical structure, curing behavior and curing kinetics of AD‐Bz were characterized by Fourier transform infrared spectroscopy, NMR spectroscopy (1H NMR and 13C NMR) and DSC, respectively. The results indicated that the activation energies (Ea) of AD‐Bz were 106.3 kJ mol−1 (Kissinger–Akahira–Sunose method) and 109.5 kJ mol−1 (Ozawa method), which are significantly lower than that of the benzoxazine derived from salicylaldehyde and 4,4′‐diamine diphenylmethane (P‐ddm). Furthermore, the thermal properties, dielectric properties and flammability properties of poly(AD‐Bz) were explored with dynamic mechanical analysis, an Agilent impedance analyzer and TGA. It was found that poly(AD‐Bz) exhibited higher heat‐resistant properties (Tg = 253.4 °C), higher thermal stability (Td,10% = 401 °C) and lower dielectric constant (εr = 3.16, 10 MHz) compared with poly(P‐ddm), favoring its application as a candidate for interlayer materials in ultra‐large‐scale integrated circuit and aerospace materials. © 2022 Society of Industrial Chemistry.

Synthesis of Bacteria-mimetic Gold Nanoparticles for Phagocytosis by Immune Cells.

Cell-based carrier exhibits inherent advantages as the next generation of drug delivery system, namely high biocompatibility and physiological function. Current cell-based carriers are constructed via direct payload internalization or conjugation between cell and payload. However, the cells involved in these strategies must be firstly extracted from the body and the cell-based carrier must be prepared in vitro. Herein, we synthesize bacteria-mimetic gold nanoparticles (GNPs) for the construction of cell-based carrier in mice. Both β-cyclodextrin (β-CD)-modified GNPs and adamantane (ADA)-modified GNPs are coated by E. coli outer membrane vesicles (OMVs). The E. coli OMVs induce the phagocytosis of GNPs by circulating immune cells, leading to intracellular degradation of OMVs and subsequent supramolecular self-assembly of GNPs driven by β-CD-ADA host-guest interactions. In vivo construction of cell-based carrier based on bacteria-mimetic GNPs avoids the immunogenicity induced by allogeneic cells and restriction by the number of separated cells. Due to the inflammatory tropism, endogenous immune cells carry the intracellular GNP aggregates to the tumor tissues in vivo. Graphical overview Collect the outer membrane vesicles (OMVs) of E. coli by gradient centrifugation (a) and coat on gold nanoparticles (GNP) surface (b) to prepare OMV-coated cyclodextrin (CD)-GNPs and OMV-coated adamantane (ADA)-GNPs (c) via ultrasonic method.

Improved emission performance of benzo[a]phenoxazine in aqueous solution through host-guest interaction.

To evaluate the contribution of host-guest chemistry in fluorescence enhancement under aqueous conditions, two benzo[a]phenoxazine derivatives with the adamantyl group were prepared. After they formed stable complexes with methyl-β-cyclodextrin, their emissions at 625-825 nm were greatly increased and fluorescence quantum yields reached 11.5-12.6% in aqueous solution. Furthermore, they were successfully applied in fluorescence labeling of organelles in HeLa cells.

Installation of the adamantyl group in polystyrene-block-poly(methyl methacrylate) via Friedel–Crafts alkylation to modulate the microphase-separated morphology and dimensions

We present the polystyrene block post-polymerization modification of PS-b-PMMA through Friedel–Crafts alkylation with adamantanols to modulate its microphase-separated morphology and dimensions.

Simultaneous determination of heparan sulfate, chondroitin/dermatan sulfates, and hyaluronan glycosaminoglycan disaccharides by high-performance liquid chromatography using a reverse-phase column with adamantyl groups

Glycosaminoglycans (GAGs), which are one of the major components of proteoglycans, play a pivotal role in physiological processes such as signal transduction, cell adhesion, growth, and differentiation. Characterization of GAGs is challenging due to the tremendous structural diversity of heteropolysaccharides with numerous sulfate or carboxyl groups. In this present study, we examined the analysis of 2-aminobenzamide (2-AB) labeled GAG disaccharides by high-performance liquid chromatography (HPLC) using a reverse-phase (RP)-column with adamantyl groups. Under the analytical conditions, 17 types of 2-AB labeled GAG disaccharides derived from heparan sulfate, chondroitin/dermatan sulfates, and hyaluronan were sequentially separated in a single analysis. The analysis time was fast with high retention time reproducibility. Moreover, the RP-HPLC column with adamantyl groups allowed the quantification of GAGs in various biological samples, such as serum, cultured cells, and culture medium.

Understanding the role of host-guest interactions in enhancing oil recovery through β‑cyclodextrin and adamantane modified copolymer

Adamantane (ADA) and β-Cyclodextrin (β-CD) modified hydrolyzed polyacrylamide (MHPAM) polymers have been confirmed to have excellent performance in enhanced oil recovery (EOR). However, the molecular mechanism of the formation of three-dimensional polymer network structure has been not yet fully understood. In this work, the cross-linked mode of MHPAM polymers and their interaction information was investigated by molecular dynamics (MD) simulations and quantum chemical (QC) calculations. Results suggest that the ADA and β-CD molecules play a pivotal molecular recognition and binding role (like hormones and receptors, antigens and antibodies) in the process of host-guest interaction. The proposed mechanism of MHPAM cross-linking in the experiments was supplemented by our MD simulations. In addition, the strong electrostatic and van der Walls (vdW) component can be explained by the overlap of positive and negative ESP/vdW side. The viscosity of hydrolyzed polyacrylamide (HPAM) was increased via the modification of ADA and β-CD, which can be attributed to the hydrophobic associations of MHPAM. Based on our results, it will allow a more informed selection of these as polymers for use in enhanced oil recovery, enabling the properties of these polymers to be tailored to a particular application.

Novel adamantane substituted polythiophenes as competitors to Poly(3-Hexylthiophene)

The investigation of poly(3-alkylthiophenes) (P3ATs) has gained great attention in the last decades. Here, we present the synthesis, experimental and theoretical study of the novel regioregular poly(3-adamantylmethylthiophene) (PMAT) and poly(3-adamantylethylthiophene) (PEAT) , characterised by a bulky adamantane side group. The prepared compounds are solution-processable in common organic solvents, possess excellent thermal stability up to 491 °C and have unique chemical endurance. The molecular ordering of the polymers was investigated by the GIWAXS technique, and PMAT was found to have the higher content of crystalline phase. The experimental absorption and fluorescence spectra of investigated polymers indicate a higher rigidity of the adamantane side group with respect to torsional rotation in solutions and in thin layers. Electrical measurements exhibit charge carrier mobilities comparable to poly(3-hexylthiophene) (P3HT) . In contrast to P3HT , adamantyl-substituted polymers show quasi-reversible reduction alongside the expected quasi-reversible oxidation, which in theory supports the ability to transport both types of electric charges. The newly synthetized regioregular adamantane substituted polythiophenes are serious competitors for a wide range of applications in electronics and optoelectronics. • Novel derivates of polythiophene, featuring the bulky adamantyl groups were synthesized. • These materials exhibit high thermal stability as well as electrical conductivity comparable to poly(3-hexylthiophene). • The materials absorb light in the 400 – 500 nm wavelength range, making them serious candidates for use in optoelectronics.

Cyclodextrin-mediated conjugation of macrophage and liposomes for treatment of atherosclerosis.

Current pharmacological treatments of atherosclerosis often target either cholesterol control or inflammation management, to inhibit atherosclerotic progression, but cannot lead to direct plaque lysis and atherosclerotic regression, partly due to the poor accumulation of medicine in the atherosclerotic plaques. Due to enhanced macrophage recruitment during atheromatous plaque progression, a macrophage-liposome conjugate was facilely constructed for targeted anti-atherosclerosis therapy via synergistic plaque lysis and inflammation alleviation. Endogenous macrophage is utilized as drug-transporting cell, upon membrane-modification with a β-cyclodextrin (β-CD) derivative to form β-CD decorated macrophage (CD-MP). Adamantane (ADA) modified quercetin (QT)-loaded liposome (QT-NP), can be conjugated to CD-MP via host-guest interactions between β-CD and ADA to form macrophage-liposome conjugate (MP-QT-NP). Thus, macrophage carries liposome "hand-in-hand" to significantly increase the accumulation of anchored QT-NP in the aorta plaque in response to the plaque inflammation. In addition to anti-inflammation effects of QT, MP-QT-NP efficiently regresses atherosclerotic plaques from both murine aorta and human carotid arteries via CD-MP mediated cholesterol efflux, due to the binding of cholesterol by excess membrane β-CD. Transcriptome analysis of atherosclerotic murine aorta and human carotid tissues reveal that MP-QT-NP may activate NRF2 pathway to inhibit plaque inflammation, and simultaneously upregulate liver X receptor to promote cholesterol efflux.

Design, Synthesis, and Application of Chiral Bicyclic Imidazole Catalysts.

Asymmetric organocatalysis has been considered to be an efficient and reliable strategy for the stereoselective preparation of optically active chemicals. In particular, chiral tertiary amines as Lewis base organocatalysts bearing core structures including quinuclidine, dimethylaminopyridine (DMAP), N-methylimidazole (NMI), amidine, etc. have provided new and powerful tools for various chemical transformations. However, due to the limitations in structural complexity, synthetic difficulty, low catalytic efficiency, and high cost, the industrial application of such catalysts is still far from being widely adopted. Therefore, the development of new chiral tertiary amine catalysts with higher activity and selectivity is greatly desired.In order to address the contradiction between activity and selectivity caused by the ortho group, a bicyclic imidazole structure bearing a relatively large bond angle ∠θ was designed as the skeleton of our new catalysts. 6,7-Dihydro-5H-pyrrolo[1,2-a]imidazole (abbreviated as DPI) and 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine (abbreviated as TIP) are two of the utilized skeletons. In addition to obtaining satisfactory catalytic activity, excellent enantioselectivity would also be expected because the stereocontrol R group is neither far nor close to the catalytic active site (sp2-N atom) and is adjustable. Based on this skeleton, a family of chiral bicyclic imidazole catalysts were easily prepared and successfully applied in several enantioselective reactions for the synthesis of a variety of valuable chiral compounds.6,7-Dihydro-5H-pyrrolo[1,2-a]imidazole (abbreviated as DPI) is the predominantly utilized skeleton. First, HO-DPI, the key intermediate of the designed chiral bicyclic imidazole catalysts, could be efficiently synthesized from imidazole and acrolein, then separated by kinetic resolution or optical resolution. Second, Alkoxy-DPI, the alkyloxy-substituted chiral bicyclic imidazole catalysts, were synthesized by a one-step alkylation from HO-DPI. This type of catalyst has been successfully applied in asymmetric Steglich rearrangement (C-acylation rearrangement of O-acylated azlactones), asymmetric phosphorylation of lactams, and a sequential four-step acylation reaction. Third, Acyloxy-DPI, the acyloxy-substituted chiral bicyclic imidazole catalysts, were synthesized with a one-step acetylative kinetic resolution from racemic HO-DPI or acylation from enantiopure HO-DPI. The catalyst AcO-DPI has been successfully applied in enantioselective Black rearrangement and in direct enantioselective C-acylation of 3-substituted benzofuran-2(3H)-ones and 2-oxindoles. Fourth, Alkyl-DPI was synthesized via a two-step reaction from racemic HO-DPI and separated easily by resolution. The catalyst Cy-DPI has been successfully applied in dynamic kinetic resolution of 3-hydroxyphthalides through enantioselective O-acylation. Cy-PDPI was synthesized through a Cu-catalyzed amidation from Cy-DPI and successfully applied in the kinetic resolution of secondary alcohols with good to excellent enantioselectivities. Finally, the carbamate type chiral bicyclic imidazole catalysts, Carbamate-DPI, were readily synthesized from HO-DPI, and the catalyst Ad-DPI bearing a bulky adamantyl group was successfully applied in the synthesis of the anti-COVID-19 drug remdesivir via asymmetric phosphorylation. Alongside our initial work, this Account also introduces four elegant studies by other groups concerning asymmetric phosphorylation utilizing chiral bicyclic imidazole catalysts.In summary, this Account focuses on the chiral bicyclic imidazole catalysts developed in our group and provides an overview on their design, synthesis, and application that will serve as inspiration for the exploration of new organocatalysts and related reactions.

A Multiple-Stimuli-Responsive Amphiphilic Copolymer for Antifouling and Antibacterial Functionality via a "Resistance-Kill-Release" Mechanism.

In recent years, polymers with stimuli-responsive properties have been increasingly reported on due to their diverse applications. However, most of the studies have only focused on the performance of polymers under specific scenarios. The laws of changes in the properties in response to various external stimuli have been less systematically and quantitatively studied. In this paper, we prepared an amphiphilic polymer (PadaMX and PAdaM3QA−X) with temperature-, pH-, ion-, and β-cyclodextrin (β-CD)-responsive properties. According to the cloud point tested by the UV-Vis method, the lower critical soluble temperature (LCST) of PAdaM3QA−10% was more sensitive to a change in pH and less sensitive to a change in ions compared with PadaM3 due to quaternized side chains with a stronger intramolecular mutual repulsion. We then fabricated the coatings with responsive properties by immobilizing the adamantyl groups on β-CD-modified surfaces. The hydrophilicity of the coatings was improved after quaternization, as proven by the water contact angle (WCA) measurement. The antifouling and antibacterial performance was further evaluated via the fluorescence intensity of bovine serum albumin (BSA) adsorbed on the surfaces and the spread plate method. A 78.4% BSA desorption rate and a 96.8% sterilization rate were achieved by the PAdaM3QA−10% coating. In summary, this work prepared a multiple-stimuli-responsive amphiphilic copolymer for antifouling and antibacterial functionality via a “resistance–kill–release” mechanism.

O,N,S-tris-chelating ligand scaffolds flanked with cyclohexyl or adamantyl substituents anchored with diorganotin(IV) moieties: synthesis, structures and cytotoxicity

The O,N,S-tris-chelating ligand, H2NSCN-N-C(H)ArO− constitutes an attractive scaffold in coordination chemistry and we have expanded this scaffold by installing an alkyl group of different steric hindrance. Thus, the ligand scaffolds containing O,N,S (Ln) differ with respect to the chemical link between the coordinating O atoms, which is either a phenol or a naphthol moiety and carrying a cyclohexyl or a adamantyl groups (L1, phenol and cyclohexyl; L2, naphthol and cyclohexyl; L3, phenol and adamantyl; L4, naphthol and adamantyl). Six novel diorganotin(IV)-Ln compounds 1–6 were synthesized and structurally characterized. The solid-state structures were deduced from single crystal X-ray diffraction data, and revealed the Sn(IV) cations adopting square pyramid (in 2, 3 and 4) or trigonal bipyramid (in 1, 5 and 6) geometries with coordination spheres comprising κ-N,O,S (κ-N,S in 1) ligand chelators and two methyl or phenyl groups (plus a hydrosulfide in 1) co-ligands. Solution state characterizations were achieved by detailed 1H, 13C, 15N and 119Sn NMR analysis including selected 2D experiments. In vitro cytotoxic activities of the compounds were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against human histiocytic lymphoma U-937 cells. The IC50 values revealed better activities of diphenyltin(IV) compounds 4–6 as compared to the respective pro-ligands and doxorubicin. More importantly, compounds 4–6 demonstrated maximum inhibition in U-937 cells (IC50 = 0.47–0.99 μM), with negligible effect on human peripheral blood mononuclear cells (PBMC). Compounds 4–6 effectively inhibited cell viability event, which was confirmed by detecting cytotoxicity, Live & Dead and Lactate dehydrogenase (LDH) release assays.