Introduction Of Thiol Groups Research Articles

Polyfluorene-based Conjugated Nanocomposites with In-situ Gold Nanoparticles: Synthesis via Rational Chemical Passivation and Characterization of Supramolecular Fibrillar Structures

We present a rational and innovative chemical approach for synthesizing and characterizing conjugated polymer nanocomposites as direct passivation of gold nanoparticles (AuNPs), highlighting intrinsic morphologies and distinct photophysical properties in the solid state. The pioneering synthesis of polyfluorene with thiol, LaPPS79.10, revolutionized its application as a direct passivator of AuNPs, resulting in stable nanocomposites with the capacity for storage in the dry state and subsequent redispersion in organic solvent. The presence of AuNPs with average diameters of 3.5 ± 1.3 nm induced the formation of an interconnected fibrillar supramolecular network (ribbon-like) and several microdomains in the nanocomposite (LaPPS79.10+AuNPs), correlated by XRD, TEM and SEM measurements. Characterization of the polyfluorene precursor derivative, LaPPS10, revealed bundle-like morphologies with aggregation-induced emission (AIE). Introducing thiol groups into the intermediate structure induced polymer chain organization (LaPPS79.10), leading to unique straw-like and lenticular bundle morphologies, disrupting the non-planar π-π packing and quenching the emission, a case of aggregation-caused quenching (ACQ). In LaPPS79.10+AuNPs, the proximity of the π system to the Au localized surface plasmon resonance (LSPR) resulted in high absorption, negligible self-absorption, and efficient emission quenching, as well as improved thermal resistance compared to the original polymer. The unprecedented discovery of the properties resulting from the electronic interaction between the π system of the AuNPs passivating polymer and the effects of plasmonic resonance represents a significant advance in nanoscience, opening new perspectives for exciting applications in organic photovoltaic devices and metamaterials.

Synthesis and thermal characterization of porous polymeric microspheres functionalized with thiol groups

The paper presents a method of the preparation and functionalization of polymer microspheres consisting of glycidyl methacrylate (GMA) and crosslinking agents: 1,4-dimethacryloyloxybenzene (1,4DMB) and trimethylolpropane trimethacrylate (TRIM). Poly(GMA-co-1,4DMB) and poly(GMA-co-TRIM) microspheres were obtained by seed swelling polymerization. To introduce thiol groups into the microspheres structure, the reaction with thiocarboxylic acids was performed. The chemical structure of parent and modified microspheres was confirmed by FTIR and Raman spectroscopy. Elemental composition of microspheres after functionalization was determined by elemental analysis. The analysis showed the percentage of sulfur in the range of 2.78–4.51%, which corresponds to a concentration of thiol group in the range of 0.87–1.41 mmol g−1. Additionally, the porous structure of the copolymers was investigated using the low-temperature nitrogen adsorption–desorption method. The starting microspheres are characterized by a specific surface in the range of 150–160 m2 g−1, whereas functionalized copolymers indicate slightly lower surface area, of about 130 m2 g−1. The thermal stability of the materials was determined by the method of differential scanning calorimetry and thermogravimetric analysis. The course of the thermal degradation under oxidative conditions of modified microspheres is different from the starting copolymers. The functionalized microspheres showed much higher thermal stability (approximately 270 °C) compared to the starting microspheres (230–250 °C).

Surface Functionalisation and Electroless Plating of 3D-Printed Microstructures

A microelectrode with a large surface area is one of the essential components in biosensors, electronic implants, and energy harvesting systems. In particular, enzymatic biofuel cells and biosensors benefit significantly from microelectrodes with a large surface area to volume ratio because of the increased enzyme loading and hence improved the power density of the final devices. Therefore, the fabrication of microelectrodes with a large surface area will advance its application in devices. Projection-microstereolitography (PµSLA) offers the ability to fabricate three-dimensional and geometrically adjustable polymeric microstructures with well-defined complex shapes in microscale. 3D polymeric microstructures produced using PµSLA can be then coated with metal to achieve high conductivity. Microelectrodes have been created via 3D printing of polymeric structures followed by electroless plating. However, the weak adhesion of the metal to the polymer limits the practical use of the produced devices as electrodes. Here, we show the method to introduce thiol groups on the surface of PµSLA-generated polymeric microstructures to improve the adhesion between the polymer surface and gold thin film. Our results demonstrate that thiol groups on the polymer surface provide the anchoring site for gold deposition during electroless plating via gold-sulfur bonding, resulting in strong adhesion between the polymer surface and the gold layer and long-term microelectrode durability. The gold coated 3D microelectrode exhibits excellent electrical conductivity up to 1.4 × 107 S/m (35% of bulk gold). This method can offer exciting potential for constructing microelectrodes for architecture-specific applications in future energy, catalysis, and sensing.

Conductive cotton fabrics with ultrahigh washability by electroless silver plating after silane modification

Adhesion of conductive components to fabrics is very important to the application of conductive fabrics obtained by coating. The falling off of the conductive coating in laundry process will result in deteriorating conductivity and unstable signal detection when they are used as wearable textile electrodes. In order to obtain conductive fabrics with excellent washing resistance, cotton fabrics were treated with 3-Mercaptopropytrimethoxysilane (MPTS) at different temperature, concentrations and time to introduce thiol groups, then silane modified cotton fabrics were coated with silver via electroless plating. The relationship between silane grafting ratio and electrical resistance was investigated, the results indicated that the silane grafting ratio should be in some range to obtain optimum conductivity of the fabrics. The electric resistance of the obtained fabrics was as low as 0.33 Ω/sq and remained 2.49 Ω/sq after undergoing up to 200 washing cycles. The excellent washability of as-prepared conductive fabrics enables the feasibility to be applied to wearable electronic products.

Manipulation of aggregation-induced emission of thermoresponsive fluorescent polymers having Au(I)–S groups for a fluorescent chemosensor

Aggregation-induced emission (AIE) is a new technique for enhancing fluorescence. To demonstrate manipulation of near-infrared AIE by thermal stimuli for analytical use, we synthesized a thermoresponsive fluorescent polymer containing Au(I)–S bonds as near infrared fluorophores. We also examined the polymer for use as a fluorescent chemosensor based on the manipulation of AIE. The thermoresponsive fluorescent polymer was prepared from poly(N-isopropylacrylamide-co-methacrylic acid) by introducing thiol groups which were further modified to form fluorescent Au(I)–S bonds. The thermoresponsive fluorescent polymer aggregated and then fluoresced in the near infrared region due to AIE when heated above the phase transition temperature of 32 °C. The change in fluorescence intensity of the polymer was reversible by changing the solution temperature. Because the residual carboxyl groups make the thermoresponsive fluorescent polymer negatively ionizable, neutralization by the addition of positively charged analytes facilitates its aggregation to enhance fluorescence above the phase transition temperature. When hemoglobin, which has an isoelectric point of 6.8, was added to a pH 6.0 polymer solution at 40 °C, the polymer aggregated to enhance its fluorescence as a result of neutralization. A linear relationship between the hemoglobin concentration and the fluorescence intensity of the polymer was obtained for 0.5–2.0 g/L hemoglobin with a detection limit (3 s) of 0.014 g/L.

Modulated synthesis of thiol-functionalized fcu and hcp UiO-66(Zr) for the removal of silver(i) ions from water

Mercaptoacetate modulation represents an easy way of introducing thiol groups into UiO-MOFs for enhanced uptake of Ag+ from aqueous solutions.

Tuning the load of gold and magnetic nanoparticles in nanogels through their design for enhanced dual magneto-photo-thermia.

We describe a novel synthesis allowing one to enhance the load of magnetic nanoparticles and gold nanorods in nanogels. Two different structures, simple cores and core-shell, were synthesized and their heating properties upon alternating magnetic field or laser exposure are compared. Remarkably, the core-shell structure showed a greater heating capacity in the two modalities.

Thiol-functionalized PIM-1 for removal and sensing for mercury (II)

Polymers of intrinsic microporosity (PIMs) are a class of microporous polymers with rigid and contorted molecular structures. The special structures lead to incomplete space occupation, and the pores of PIMs originate from the formed void. In this work, we made attempts to expand the applications of PIMs to the aspect of heavy metal removal. First, PIM-1 was synthesized using tetrafluoroterephthalonitrile (TFTPN) and 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI) as precursors. The primary PIM-1 was quite hydrophobic, and thus could not be evenly dispersed in water, resulting in low adsorption capacity for mercury ions (Hg2+). A conversion of nitrile group in PIM-1 to thiol group was then carried out by two steps, namely carboxylation and introduction of thiol groups. The carboxylation made the polymers more active, and the final thiol-functionalization provided the polymers with hydrophilicity and affinity for Hg2+. The thiolethyl modified PIM-1 (assigned as PIM-G) and thiophenyl modified (assigned as PIM-B) possessed maximum Hg2+ adsorption capacity of 136 mg g−1 and127 mg g−1 at pH 5, respectively. Besides, the thiol-functionalized PIMs had fluorescence property and showed potential in sensing for Hg2+.

Small Physical Cross-Linker Facilitates Hyaluronan Hydrogels.

In this study, we demonstrate that small charged molecules (NH4+, GluA+, dHA+) can form physical cross-links between hyaluronan chains, facilitating polymerization reactions between synthetically introduced thiol groups (HA-DTPH). These hybrid hydrogels can be obtained under physiological conditions ideally suited for 3D cell culture systems. The type and concentration of a physical crosslinker can be adjusted to precisely tune mechanical properties as well as degradability of the desired hydrogel system. We analyze the influence of hydrogen bond formation, concentration and additional ionic interactions on the polymerization reaction of HA-DTPH hydrogels and characterize the resulting hydrogels in regard to mechanical and biocompatibility aspects.

Fabrication of Light‐Weight and Highly Conductive Copper–Carbon Nanotube Core–Shell Fibers Through Interface Design

AbstractMetal‐carbon nanotube (CNT) hybrid fibers are emerging materials for light‐weight conductors that can replace common metallic conductors. One of the main challenges to their development is the poor affinity between CNT and metals. In this work, a new approach for fabrication of CNT/Cu core‐shell fibers is demonstrated that outperforms the commercial Cu wires in terms of specific conductivity, ampacity, and strength. By introducing thiol groups to the surface of CNT fibers, a dense Cu coating with enhanced adhesion is obtained. Consequently, CNT/Cu core‐shell fibers with specific conductivity of 3.6 × 107 S m−1 and tensile strength of 1 GPa, which is almost five times higher than commercial Cu wires, are produced. Due to strong interaction of thiol functional groups and Cu atoms, the fiber can preserve its integrity and conductivity after >500 fatigue bending cycles. Furthermore, the ampacity of the composite wire reaches to 1.04 × 105 A cm−2, which corresponds to a specific ampacity two times higher than that of commercial Cu wires. The interfacial design between Cu and CNT presented here is versatile and can be implemented in other processing and deposition methods.

Functionalization of Shirasu-balloons Surface for Removal of Cadmium Ions from Contaminated Soil.

Microspheres of aluminosilicate glass from volcanic sediment, whose surfaces were modified with functional groups, Shirasu-balloons (SB), were investigated as an adsorbent to remove cadmium ions from contaminated soil. The introduction of thiol groups (-SH) on the surface of SB enabled it to adsorb cadmium ions. Meanwhile, the introduction of an alkyl group (-ODS) made the surface of SB hydrophobic, and consequently increased the mechanical strength of SB. Those adsorbents could float up on the water surface after the adsorption process. The prepared adsorbent was characterized by FTIR spectrophotometry, elemental analysis and optical microscopy for making photographic images. The adsorption of cadmium ions on the adsorbent was investigated by comparing the results by a plain SB with those by thiol-functionalized SB. The adsorption maximum for cadmium ions was 3.75 mg/g for SH-SB and 2.62 mg/g for SH-ODS-SB, respectively. The adsorption of cadmium ions on functionalized SH-SB and SH-ODS-SB fitted well to the Langmuir isotherm equation. After a shaking time of 24 h, the recovering ratios of the absorbents from soil were 73 wt% for SH-SB and 98 wt% for SH-ODS-SB absorbents. In addition, the kinetic and adsorption-desorption properties of the adsorbent were also considered.

Metal-Organic Frameworks Bearing Dense Alkyl Thiol for the Efficient Degradation and Concomitant Removal of Toxic Cr(VI).

Highly efficient removal of toxic Cr(VI) from aqueous media remains a crucial concern for ecosystem protection and public health. Herein, we demonstrated a new approach to solve this issue by constructing alkyl thiol-containing Zr-based metal-organic framework (MOF) adsorbents using simple and inexpensive mercaptosuccinic acid (MSA) and meso-dimercaptosuccinic acid (DMSA) as ligands. These chemically stable MOFs could be prepared in an uncomplicated, green, cost-effective, and scalable way. The interaction mechanism between alkyl thiol groups in MOFs and Cr(VI) was investigated in detail. Thanks to the formation of a Cr(VI)-thiolate complex and the oxidation of thiol groups, these designed MOFs not only exhibited high Cr(VI) adsorption capacities (202.0 and 138.7 mg/g for Zr-MSA and Zr-DMSA, respectively) but also displayed the immobilization ability for concomitant resultant Cr(III). Even in the presence of high concentrations of possibly coexistent interfering ions, the thiol-containing MOFs can still work effectively to decontaminate the Cr(VI) species. In addition, the strategy of introducing thiol groups into MOFs for Cr(VI) reduction and concomitant Cr(III) immobilization is universal for other MOFs, as verified by thiol-containing UiO-66 and MOF-808 prepared by a one-pot method. Therefore, our work not only produces several effective Cr(VI) adsorbents but also sets a general guideline for the construction of Cr(VI) adsorbents by introducing thiol groups into porous materials.

Injectable Shape-Holding Collagen Hydrogel for Cell Encapsulation and Delivery Cross-linked Using Thiol-Michael Addition Click Reaction.

Injectable hydrogels based on extracellular matrix-derived polymers show much promise in the field of tissue engineering and regenerative medicine. However, the hydrogels reported to date have at least one characteristic that limits their potential for clinical use, such as excessive swelling, complicated and potentially toxic cross-linking process, or lack of shear thinning and self-healing properties. We hypothesized that a collagen hydrogel cross-linked using thiol-Michael addition click reaction would be able to overcome these limitations. To this end, collagen was modified to introduce thiol groups, and hydrogels were prepared by cross-linking with 8-arm polyethylene glycol-maleimide. Rheological measurements on the hydrogels revealed excellent shear-thinning and self-healing properties. Additionally, only minimal swelling (6%) was observed over a period of 1 month in an aqueous buffer solution. Finally, tests using mesenchymal stromal cells and endothelial cells showed that the hydrogels are cell-compatible and suitable for cell encapsulation and delivery. Thus, the reported thiolated-collagen hydrogel cross-linked using thiol-Michael addition click reaction overcomes most of the challenges in the injectable hydrogel design and is an excellent candidate for cell delivery in regenerative medicine and tissue engineering applications. The hydrogel reported here is the first example of a self-healing hydrogel containing covalent cross-links.

Two-Step Elution Recovery of Cyanide Platinum Using Functional Metal Organic Resin.

A novel functional ion-exchange/adsorption metal organic resin (MOR), TEBAC-HKUST-1, was prepared and characterized. Ethanedithiol was used as the grafting agent to introduce thiol groups onto HKUST-1, and 4-vinylbenzyl chloride was then grafted onto SH-HKUST-1 using thiol groups. Finally, the quaternary ammonium functional group was immobilized onto the carrier by performing a quaternization reaction. The structure and property of TEBAC-HKUST-1 MOR were characterized by TGA, N2 adsorption–desorption, FTIR, SEM, and XRD. TEBAC-HKUST-1 MOR was used to remove metal cyanide complexes from wastewater. The adsorption was rapid, and the metal cyanide complexes including Pt(CN)42−, Co(CN)63−, Cu(CN)32−, and Fe(CN)63− were removed in 30 min. TEBAC-HKUST-1 MOR exhibited a high stability in neutral and weak basic aqueous solutions. Furthermore, Pt(II) could be efficiently recovered through two-step elution. The recovery rate of Pt(II) for five cycles were over 92.0% in the mixture solution containing Pt(CN)42−, Co(CN)63−, Cu(CN)32−, and Fe(CN)63−. The kinetic data were best fitted with the pseudo second-order model. Moreover, the isothermal data were best fitted with the Langmuir model. The thermodynamic results show that the adsorption is a spontaneous and exothermic process. TEBAC-HKUST-1 MOR not only exhibited excellent ability for the rapid removal of metal cyanide complexes, but also provided a new idea for the extraction of noble metals from cyanide-contaminated water.

Porphyrin‑silver nanoparticles hybrids: Synthesis, characterization and antibacterial activity

The preparation of light-activated hybrid antibacterial agent combining the porphyrin molecules, bound to the silver nanoparticles (AgNPs) surface is reported. AgNPs were synthesized by N-methyl-2-pyrrolidone-initiated reduction without additional reducing agents. The chemical structure of protoporphyrin IX was modified with the aim to introduce thiol groups. The size distribution and shape features of AgNPs were checked using TEM and HRTEM microscopies. The introduction of thiol groups into the porphyrin was proved by IR spectroscopy. The AgNPs-porphyrin binding was performed in solution and confirmed by fluorescence quenching, Raman spectroscopy and energy-filtered transmission electron microscopy (EFTEM). The antibacterial tests were performed against S. epidermidis and E. coli upon to LED illumination and in the dark. The synergetic effect of AgNPs and porphyrin as well as light activation of the created antibacterial conjugates were observed.

Removal of phosphate ions from wastewater by treated hydrogel based on chitosan

Chitosan/ Gelatin/2-(Dimethylamino) ethyl methacrylate (Cs/Gltn/PDMAEMA) hydrogel was synthesized by gamma irradiation for the expulsion of phosphate ions from wastewater. Chemical adjustment of the hydrogel with thiourea was performed to introduce thiol groups Cs/Gltn/PDMAEMA-treated. More over trapping of SiO2 into the hydrogel matrix to acquire Cs/Gltn/PDMAEMA/SiO2 composite. It was found that the gelation increases with increasing PDMAEMA content in the hydrogel. The maximum gelation performed at an equal ratio of Cs/Gltn at a radiation dose of 15 kGy. The adsorption capacities of the prepared systems towards phosphate ions were investigated. It was obtained that the maximum removal is achieved at pH 6 through 180 min. However, the removal percent decreases with increasing phosphate ions concentration and temperature. The ability of the prepared adsorbents towards phosphate ions removal are ascending ordered in the sequence of Cs/Gltn/PDMAEMA hydrogel, Cs/Gltn/PDMAEMA-treated , and Cs/Gltn/PDMAEMA/SiO2 composite. The pseudo-second-order equation fits well the adsorption kinetics. The adsorption isotherm follows the Freundlich model higher than the Langmuir model

Labeling Antibodies Using a Maleimido Dye.

Fluorophore-maleimide derivatives are effective for labeling sulfhydryl-containing molecules. Maleimide groups react with free thiols at pH 6.5-7.5 forming a covalent bond. Reducing agents should be avoided during the conjugation step. This protocol uses the cross-linker N-succinimidyl S-acetylthioacetate (SATA) to introduce thiol groups on the antibody while maintaining the divalent nature of the antibody. Alternatively, the antibody can be digested and reduced to monovalent Fab fragments, which can then be labeled directly with maleimido derivatives.

Regulation of Protein Structural Changes by Incorporation of a Small-Molecule Linker.

Proteins have the potential to serve as nanomachines with well-controlled structural movements, and artificial control of their conformational changes is highly desirable for successful applications exploiting their dynamic structural characteristics. Here, we demonstrate an experimental approach for regulating the degree of conformational change in proteins by incorporating a small-molecule linker into a well-known photosensitive protein, photoactive yellow protein (PYP), which is sensitized by blue light and undergoes a photo-induced N-terminal protrusion coupled with chromophore-isomerization-triggered conformational changes. Specifically, we introduced thiol groups into specific sites of PYP through site-directed mutagenesis and then covalently conjugated a small-molecule linker into these sites, with the expectation that the linker is likely to constrain the structural changes associated with the attached positions. To investigate the structural dynamics of PYP incorporated with the small-molecule linker (SML-PYP), we employed the combination of small-angle X-ray scattering (SAXS), transient absorption (TA) spectroscopy and experiment-restrained rigid-body molecular dynamics (MD) simulation. Our results show that SML-PYP exhibits much reduced structural changes during photo-induced signaling as compared to wild-type PYP. This demonstrates that incorporating an external molecular linker can limit photo-induced structural dynamics of the protein and may be used as a strategy for fine control of protein structural dynamics in nanomachines.

Stretchable gelatin/silver nanowires composite hydrogels for detecting human motion

A stretchable gelatin/silver nanowires (GE-AgNWs) composite hydrogel with enhanced mechanical properties and electrical conductivity has been prepared through chemical grafting and physical crosslinking. By introducing thiol groups on the gelatin molecular chain, better interactions between the reinforcing AgNWs and the gelatin molecules in the hydrogel networks was established. The introduced AgNWs not only reinforced the hydrogels but also formed effective electrical pathways to endow the hydrogel with good conductivity. By using the “salting out” effect, additional physical crosslinks were introduced to the hydrogel network so that the composite hydrogel became stretchable. The resulting composite hydrogel was not only biocompatible, but could also be used as a strain sensor to detect multiple human motions. Hence, these hydrogels have the potential to be used in biosensors, electric skins, and health monitoring applications.

Synthesis and characterization of thiolated hexanoyl glycol chitosan as a mucoadhesive thermogelling polymer

BackgroundMucoadhesive polymers, which may increase the contact time between the polymer and the tissue, have been widely investigated for pharmaceutical formulations. In this study, we developed a new polysaccharide-based mucoadhesive polymer with thermogelling properties.MethodsHexanoyl glycol chitosan (HGC), a new thermogelling polymer, was synthesized by the chemical modification of glycol chitosan using hexanoic anhydride. The HGC was further modified to include thiol groups to improve the mucoadhesive property of thermogelling HGC. The degree of thiolation of the thiolated HGCs (SH-HGCs) was controlled in the range of 5–10% by adjusting the feed molar ratio. The structure of the chemically modified polymers was characterized by 1H NMR and ATR-FTIR. The sol-gel transition, mucoadhesiveness, and biocompatibility of the polymers were determined by a tube inverting method, rheological measurements, and in vitro cytotoxicity tests, respectively.ResultsThe aqueous solution (4 wt%) of HGC with approximately 33% substitution showed a sol-gel transition temperature of approximately 41 °C. SH-HGCs demonstrated lower sol-gel transition temperatures (34 ± 1 and 31 ± 1 °С) compared to that of HGC due to the introduction of thiol groups. Rheological studies of aqueous mixture solutions of SH-HGCs and mucin showed that SH-HGCs had stronger mucoadhesiveness than HGC due to the interaction between the thiol groups of SH-HGCs and mucin. Additionally, we confirmed that the thermogelling properties might improve the mucoadhesive force of polymers. Several in vitro cytotoxicity tests showed that SH-HGCs showed little toxicity at concentrations of 0.1–1.0 wt%, indicating good biocompatibility of the polymers.ConclusionsThe resultant thiolated hexanoyl glycol chitosans may play a crucial role in mucoadhesive applications in biomedical areas.