High Density Of Functional Groups Research Articles

Preparation of functionalized magnetic nanoparticles bearing sulfonic acid as an effective reusable solid acid catalyst for the synthesis of benzothiazoles

In this study, solid acid magnetic nanoparticles Fe3O4@SiO2-S-Bu-SO3H were prepared under appropriate conditions and characterized by various analytical techniques including FT-IR, XRD, FE-SEM, EDX, and VSM. Finally, the catalytic activity of the synthesized Fe3O4@SiO2-S-Bu-SO3H MNPs was investigated for the synthesis of valuable benzothiazole derivatives by the condensation reaction of ortho-aminothiophenol and various aldehydes under ultrasonic conditions. In the presence of the inexpensive, environment-friendly, magnetically recoverable solid acid catalyst, the benzothiazoles were obtained as pure target products in excellent yields (90–98%) and short reaction times (3–11 min). The synthesized Fe3O4@SiO2-S-Bu-SO3H MNPs show great catalytic activity because of the combined effect of Brønsted acidity and high functional group density. This solid acid magnetic nanocatalyst is reusable for several cycles and can be easily segregated from the reaction mixture.

Two all-biomass cellulose/amino acid spherical nanoadsorbents based on a tri-aldehyde spherical nanocellulose II amino acid premodification platform for the efficient removal of Cr(VI) and Cu(II)

Adsorbents consisting of spherical nanoparticles exhibit superior adsorption performance and hence, have immense potential for various applications. In this study, a tri-aldehyde spherical nanoadsorbent premodification platform (CTNAP), which can be grafted with various amino acids, was synthesized from corn stalk. Subsequently, two all-biomass spherical nanoadsorbents, namely, cellulose/l-lysine (CTNAP-Lys) and cellulose/L-cysteine (CTNAP-Cys), were prepared. The morphologies as well as chemical and crystal structures of the two adsorbents were studied in detail. Notably, the synthesized adsorbents exhibited two important characteristics, namely, a spherical nanoparticle morphology and cellulose II crystal structure, which significantly enhanced their adsorption performance. The mechanism of the adsorption of Cr(VI) onto CTNAP-Lys and that of Cu(II) onto CTNAP-Cys were studied in detail, and the adsorption capacities were determined to be as high as 361.69 (Cr(VI)) and 252.38 mg/g (Cu(II)). Using the proposed strategy, it should be possible to prepare other all-biomass cellulose/amino acid spherical nanomaterials with high functional group density for adsorption, medical, catalytic, analytical chemistry, corrosion, and photochromic applications.

DNA nanostructures as biomolecular scaffolds for antigen display.

Nanoparticle-based vaccines offer a multivalent approach for antigen display, efficiently activating T and B cells in the lymph nodes. Among various nanoparticle design strategies, DNA nanotechnology offers an innovative alternative platform, featuring high modularity, spatial addressing, nanoscale regulation, high functional group density, and lower self-antigenicity. This review delves into the potential of DNA nanostructures as biomolecular scaffolds for antigen display, addressing: (1) immunological mechanisms behind nanovaccines and commonly used nanoparticles in their design, (2) techniques for characterizing protein NP-antigen complexes, (3) advancements in DNA nanotechnology and DNA-protein assembly approach, (4) strategies for precise antigen presentation on DNA scaffolds, and (5) current applications and future possibilities of DNA scaffolds in antigen display. This analysis aims to highlight the transformative potential of DNA nanoscaffolds in immunology and vaccinology. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Screening of high-efficiency crosslinking agents for poly(N,N-dimethylaminoethyl methacrylate) and performance of its nanofiltration membranes

Poly(N,N-dimethylaminoethyl methacrylate) (PDM) is a water-soluble polymer that can be crosslinked via a quaternization reaction that takes 4–20 h. Polyhalogenated hydrocarbons with different structures were screened to identify high-efficiency crosslinking agents for PDM. For this purpose, the gelation time of bulk crosslinked PDM and the separation performance of interfacially crosslinked PDM membranes were investigated. Use of bromohydrocarbons with benzylic and allylic types and high functional group density can afford the rapid quaternization reaction of PDM. PDM nanofiltration membranes were prepared via interfacially crosslinking PDM with 1,3,5-tris(bromomethyl)benzene (TBB), and the effects of membrane preparation conditions (including PDM concentration, coating time, TBB concentration, and crosslinking time) on the permeation and separation performances of as-prepared membranes were investigated. The PDM membrane prepared at a PDM concentration of 6 g/L, TBB concentration of 40 mmol/L, coating time of 30 s, and crosslinking time of 30 s exhibited a water flux of 20.3 L/(m2·h) and a salt rejection of 90%, when the membrane was treated with a 1000 mg/L MgSO4 aqueous solution at 0.8 MPa pressure. The PDM membrane was positively charged and the extent of salt rejection followed the order MgCl2 > NaCl ≈ MgSO4 > Na2SO4. The membrane also exhibited good antifouling properties and chlorine resistance.

Enhanced electrochemical CO2 reduction performance of cobalt phthalocyanine with precise regulation of electronic states.

Herein, we report a facile strategy for constructing hybrid coordination configurations by combining functionalized graphene quantum dots (GQDs) with CoPc (CoPc/R-GQDs, with R being -NH2 or -OH) for electrochemical CO2 reduction. Benefiting from the high density of functional groups that can be provided by GQDs and the strong electron-donating property of -NH2, the examined CoPc/NH2-GQDs achieved a 100% faradaic efficiency for CO formation (FECO) at -0.8 to -0.9 V vs. RHE, and high FECO (over 90%) over a wide potential range of 500 mV. This work has presented a novel approach for catalyst design, specifically involving molecular engineering of quantum dots, which can also be applied to other essential electrochemical reactions.

Ascorbic Acid-Modified Silicones: Crosslinking and Antioxidant Delivery.

Vitamin C is widely used as an antioxidant in biological systems. The very high density of functional groups makes it challenging to selectively tether this molecule to other moieties. We report that, following protection of the enediol as benzyl ethers, the introduction of an acrylate ester at C1 is straightforward. Ascorbic acid-modified silicones were synthesized via aza-Michael reactions of aminoalkylsilicones with ascorbic acrylate. Viscous oils formed when the amine/acrylate ratios were <1. However, at higher amine/acrylate ratios with pendent silicones, a double reaction occurred to give robust elastomers whose modulus is readily tuned simply by controlling the ascorbic acid amine ratio that leads to crosslinks. Reduction with H2/Pd removed the benzyl ethers and led to increased crosslinking, and either liberated the antioxidant small molecule or produced antioxidant elastomers. These pro-antioxidant elastomers show the power of exploiting natural materials as co-constituents of silicone polymers.

Influence of polydopamine functionalization on the rapid protein immobilization by alternating current electrophoretic deposition

Biomolecule immobilization onto implant surfaces is an interesting approach which allows fine-tuning the biological response upon implantation. However, the relatively low adsorption rates seen in current methodologies typically lead to long processing times, which can affect the activity of the biomolecules. Here, we investigate the effect of combining a bioinspired polydopamine (PDA) functionalization strategy with alternating current electrophoretic deposition (AC-EPD) for the immobilization of bovine serum albumin (BSA) on Ti6Al4V. PDA films introduce a high density of functional groups on the metal surface for the permanent attachment, while AC-EPD has the potential to actively concentrate biomolecules at the implant surface within a short time. First, PDA films were optimized in terms of the dopamine (DA) starting concentration. Next, amine-rich PDA-functionalized Ti6Al4V substrates served as electrodes during AC-EPD of BSA. While an improved deposition yield could already be observed for the PDA and AC-EPD strategies individually, significant merit lays in their combination, as was revealed by thicker proteinaceous deposits on the PDA-functionalized Ti6Al4V serving as anode during the high-amplitude half cycle of the AC signal. This provides a proof-of-concept for the synergistic effect of a PDA coupling chemistry in combination with AC electrophoresis as a time-efficient coating methodology for the proteins.

Robust Mesoporous Functional Hydrogen-Bonded Organic Framework for Hypochlorite Detection.

Although tremendous progress has been achieved in the field of hydrogen-bonded organic frameworks (HOFs), the low stability, small/none pores, and difficult functionality severely obstruct their development. Herein, a novel robust mesoporous HOF (HOF-FAFU-1) decorated with a high density of free hydroxy moieties has been designed and readily synthesized in the de novo synthesis. In HOF-FAFU-1, the planar building blocks are connected to each other by typical intermolecular carboxylate dimers to form two-dimensional (2D) layers with sql topology, which are further connected to their adjacent layers by face-to-face π-π interactions to obtain a three-dimensional (3D) open mesoporous framework. Owing to the high density of intermolecular hydrogen bonding and strong π-π interactions, HOF-FAFU-1 is very stable, allowing it to retain its structure in aqueous solutions with a pH range of 1-9. Benefiting from the decorated hydroxy moieties, HOF-FAFU-1 was exploited as a fluorescent sensor for hypochlorite detection in water media by a turn-off mode, which cannot be realized by its nonhydroxy groups anchoring counterpart (HOF-TCBP). The proposed sensing system is highly efficient, validated by a very broad linear range (0-0.45 mM), fast response (15 s), and small limit of detection (LOD) (1.32 μM). The fluorescent quenching of HOF-FAFU-1 toward hypochlorite was also investigated, mainly being ascribed to the transformation of building blocks from the fluorescent reduced state to the nonfluorescent oxidative state. This work not only demonstrates that HOFs integrated with high stability and large pores as well as high density of functional groups can be simultaneously realized by judicious design of building blocks but also conceptually elucidates that such HOFs can effectively extend the application fields of HOFs.

Sustainably closed loop recycling of hierarchically porous polymer microbeads for efficient removal of cationic dyes

Herein, we designed and fabricated a hierarchically porous crosslinked polymeric microbead (PCP) with high density of functional groups for selective adsorption of cationic dyes from water.

Convergent Synthesis of Branched Metathesis Polymers with Enyne Reagents.

Branched polymers have found utility in an array of fields due to the high density of functional groups combined with unique physical properties. Despite the abundant methods reported to synthesize various branched structures, controlling parameters such as the location of branch points and molecular weight distribution still remains a challenge. This report explores the ability of enyne-containing branching agents to synthesize star and miktoarm star polymers through a convergent synthesis pathway using ring-opening metathesis polymerization (ROMP). The branching agents contain an enyne metathesis terminator covalently linked to a norbornene monomer. When these agents are introduced into a living ROMP, macromonomers are generated in situ that continue to propagate via a grafting-through process with the remaining living chains. This strategy permits control over the degree of polymerization of the star arms, control of the number of star arms, and chain-extension with additional monomer to produce functional asymmetric miktoarm star polymers.

A systematic review ofcarbohydrate-based bioactive molecules for Alzheimer's disease.

Theabundance, low cost, highdensity of functional groups and ease of purification of carbohydrates are among the most important features that make them a prime candidate for designing therapeutics. Several carbohydrate-based molecules, of both natural and synthetic origin, are known for their wide range of therapeutic activities. The incorporation of acarbohydrate moiety not only retains the pharmacological characteristics of amolecule but also improves itsactivity. Several sugar conjugates have beendesigned and reported to inhibit acetylcholinesterase, β-amyloidand tau aggregation. This systematic review provides a brief overview of carbohydrate-based bioactive molecules having anti-Alzheimer'sactivityalong with improved therapeutic potential. Most importantly, several reported carbohydrate-based molecules for Alzheimer's disease act on β-amyloid aggregation, tau protein, cholinesterase andoxidative stress, with enhanced pharmacokineticand mechanistic properties. The prospect of designing carbohydrate-based molecules for Alzheimer's disease will definitelyprovide potential opportunities to discover novel carbohydrate-based drugs.

MXene Coupled with CRISPR-Cas12a for Analysis of Endotoxin and Bacteria

With hydrophilic surface and high density of functional groups, MXene can efficiently adsorb single-stranded DNA to enhance target-induced strand release and quench the fluorescence. Herein, MXene is coupled with CRISPR-Cas12a to sensitively detect LPS and bacteria. Specifically, the aptamer is well designed to initiate the trans-cleavage activity of CRISPR-Cas12a to indiscriminately cleave single-stranded DNA, resulting it to be far away from MXene and the recovery of fluorescence. The target can effectually induce the release of the aptamer strand from the hybrid duplex with the assistance of MXene. The formed aptamer/target complex will inhibit the activation of CRISPR-Cas12a and its trans-cleavage on single-stranded DNA. The established method can selectively and sensitively quantify LPS and Gram-negative bacteria in different samples with detection limits of 11 pg/mL and 23 CFU/mL, respectively. Our study provides a new insight for exploration of universal analytical methods based on MXene coupled with CRISPR-Cas12a.

Instant Gelation System as Self-Healable and Printable 3D Cell Culture Bioink Based on Dynamic Covalent Chemistry.

The rapid development of additive manufacturing techniques in the field of tissue regeneration offers unprecedented success for artificial tissue and organ fabrication. However, some limitations still remain for current bioinks, such as the compromised cell viability after printing, the low cross-linking efficiency leading to poor printing resolution and speed due to the relatively slow gelation rate, and the requirement of external stimuli for gelation. To address these problems, herein, a biocompatible and printable instant gelation hydrogel system has been developed based on a designed hyperbranched poly(ethylene glycol) (PEG)-based multihydrazide macro-cross-linker (HB-PEG-HDZ) and an aldehyde-functionalized hyaluronic acid (HA-CHO). HB-PEG-HDZ is prepared by the postfunctionalization of hyperbranched PEG-based multivinyl macromer via thiol-ene chemistry. Owing to the high functional group density of HB-PEG-HDZ, the hydrogel can be formed instantly upon mixing the solutions of two components. The reversible cross-linking mechanism between the hydrazide and aldehyde groups endows the hydrogel with shear-thinning and self-healing properties. The minimally toxic components and cross-linking chemistry allow the resulting hydrogel to be a biocompatible niche. Moreover, the fast sol-to-gel transition of the hydrogel, combining all of the advanced characteristics of this platform, protects the cells during the printing procedure, avoids their damage during extrusion, and improves the transplanted cell survival.

Protein interactions and conformations on graphene-based materials mapped using a quartz-crystal microbalance with dissipation monitoring (QCM-D)

Graphene-based materials have shown significant potential for biomedical applications including biosensors, cell scaffolds and drug delivery. However, the interaction of complex biomacromolecules like proteins with graphene and its derivatives, graphene oxide (GO) and reduced (r)GO, remains poorly understood. Here, we demonstrate that the quartz-crystal microbalance with dissipation monitoring (QCM-D) technique can be used to systematically study the interaction dynamics of a typical protein, bovine serum albumin (BSA), with graphene materials of varying degrees of functionalisation. We find significant differences in molecular orientation and confirmation, mass adsorption and biochemical functionality of BSA on different graphene surfaces, determined by both the population of functional groups of GO and the protein concentration. The dominant forces during the adsorption of biomolecules onto GO and rGO are shown to be hydrophilic and hydrophobic interactions, respectively. The GO surface yielded higher BSA adsorption than both rGO and control standard gold electrodes due to the high density of functional groups. The biochemical functionality of adsorbed BSA was investigated through the interaction with its anti-BSA antibody counterpart. BSA on GO can retain its binding sites while, in contrast, a denatured ad-layer of BSA forms on the rGO followed by further binding of active BSA molecules, depending on the concentration of the protein. Intermediate conformations are observed for partially-reduced GO. These results also suggest that QCM-D is a viable readout technique for graphene-based biosensors. This QCM-D approach could be further extended to study the interaction of a host of biomolecules and their assemblies, including whole cells, with 2-dimensional materials.

Green acid-free hydrolysis of wasted pomelo peel to produce carboxylated cellulose nanofibers with super absorption/flocculation ability for environmental remediation materials

Carboxylated nanocellulose hold great application potential and research value in environmental remediation owing to its eco-friendly nature, high specific surface area, high density of functional groups and abundant reserves properties. In present work, a new type of cellulose nanofibers (CNF) with high aspect ratio and high density of carboxyl groups were prepared by directly thermo-oxidizing natural wasted pomelo peel with H2O2. The effects of reaction time on the content of carboxyl groups, morphology, and thermal stability of CNF were investigated. It is found that pomelo-CNF (POCNF) with larger aspect ratio of 169 and carboxyl group contents of 1.711 ± 0.173 mmol/g was fabricated by reacting at 60 °C for 6 h. Furthermore, the high density of carboxyl groups of POCNF allowed it to graft functional polyetherimide (PEI) on the surface of nanocellulose, and the resulting PNOCNF-PEI showed excellent adsorption performance to pollutants, such as malachite green (MG) and Cu(II), with adsorption capacity of 530 mg/g to MG and 74.2 mg/g to Cu(II). Moreover, the adsorbent showed excellent reusability. Besides, the possible adsorption kinetics/mechanism of nanocelluloses to various pollutants has been provided. The simple preparation process and excellent properties of POCNF made it become a viable candidate as environmental remediation material.

A cellulose-based adsorbent with pendant groups of quaternary ammonium and amino for enhanced capture of aqueous Cr(VI)

As a promising candidate of Cr(VI) decontamination, cellulose is limited in the Cr(VI) uptake due to its poor accessibility. Herein, We describe the synthesis of a novel cellulose-based adsorbent (PQC, where P and QC designate the polyethylenimine and quaternized cellulose, respectively) with functional groups of quaternary ammonium and amino for enhanced capture of Cr(VI) from water. For preparing PQC, cellulose is first quaternized homogeneously, followed by grafting and/or cross-linking with polyethylenimine in the presence of epichlorohydrin. The PQC follows the Langmuir isotherm and presents a maximum Cr(VI) uptake capacity of 490.3 mg/g at 30 °C and initial pH about 2.0, much higher than many other reported cellulose-based adsorbents. The adsorption of PQC is spontaneous and endothermic, which follows the pseudo-second-order kinetic model and achieves the equilibrium after contacting about 50 min. Furthermore, the PQC, with favorable reusability, can work well in a high coexisting anion concentration. These excellent absorption performances are attributed to its physicochemical properties such as the robust porous structure and high density of functional groups including quaternary ammonium, amino and hydroxyl, which improve the availability to capture or reduce Cr(VI). This work demonstrates the significant potential of cellulose-based adsorbent for remediating aqueous Cr(VI).

Structural design of a high sensitivity biomass cellulose-based colorimetric sensor and its in situ visual recognition mechanism for Cu2+

A novel biomass cellulose-based colorimetric sensor (DAC-PDH) was prepared by a Schiff base reaction between the aldehyde groups of dialdehyde cellulose (DAC) and the amino groups of 2,6-pyridine dihydrazide (PDH). The as-prepared sensor (DAC-PDH) showed selective recognition of Cu2+ and a visual colour change from white to green. The visual limit of detection for Cu2+ was 10−7 mol/L. Furthermore, DAC-PDH responded to Cu2+ within 30 s by the method of dynamic condition. The sensor possessed the properties of a high density of functional groups (CO, NH, NH2), a large external surface area, a short transit distance and flexibility; thus, Cu2+ can be rapidly absorbed and enriched on the DAC-PDH through multi-dentate ligand chelation between Cu2+ and the carbonyl groups (CO) and the amino groups (NH, NH2) of DAC-PDH. The as-prepared DAC-PDH colorimetric sensor exhibits promising prospects for in situ identification of Cu2+.

Sequential Nucleophilic "Click" Reactions for Functional Amphiphilic Homopolymers.

Amphiphilic homopolymers with high densities of functional groups are synthetically challenging. Thiol-yne nucleophilic click reactions have been investigated to introduce multiple functional groups in polymers with high density. An electron deficient alkyne group bearing methacrylate monomer was polymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Subsequently, the electron deficient alkyne group on polymer side chain was readily reacted with a thiol reagent using triethylamine (TEA) as the organocatalyst. This reaction was found to be very efficient under mild conditions. The resultant homopolymer bearing thiol vinyl ether functional groups could perform a second thiol addition with a stronger base, such as triazabicyclodecene (TBD), to prepare multifunctional homopolymers. This stepwise addition process was monitored by 1H NMR as well as gel permeation chromatography. The fidelity of this method was demonstrated by attaching four different functionalities, including both hydrophobic and hydrophilic moieties. Furthermore, these dual functionalized polymers bearing dithio-acetal groups are sensitive to reactive oxygen species (ROS), which compromises the host-guest properties of the assembly in response to this stimulus. The ROS responsive polymers reported here may have potential use in therapeutic delivery.

On the intriguing emission characteristics of size tunable carbon dots derived from functionalized multi-walled carbon nanotubes

Abstract Aqueous dispersions of carbon dots (C-dots) showing size tunable multi-colours in day light are obtained through surface functionalization of multi-walled carbon nanotubes (MWCNTs). The size of the C-dots varies with the functionalization temperature and smaller C-dots are found to be formed, at higher temperatures. The average size of the C-dots synthesized at temperatures of 100 °C, 80 °C and 60 °C lies in the range 6 nm–18 nm, based on transmission electron microscopy (TEM) images. The C-dots synthesized at these temperatures exhibit blue, green and golden yellow colours in day light without being excited by any external source. The structural characterizations using X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy confirm the presence of a high density of functional groups on the surfaces of the C-dots, giving rise to high aqueous solubility. Compared to the Raman spectrum of the MWCNTs, the spectrum of the C-dots shows a significant increase in the intensity of the defect related D band with respect to that of the crystalline G-band, which indicates the presence of a high concentration of defects and the formation of smaller sp2 carbon clusters. The synthesized C-dots exhibit size dependent optical absorption and emission characteristics. The intriguing optical properties of these C-dots, which include the multi-colour emission at day light and the excitation wavelength and the pH dependent photoluminescence emission, can be mainly attributed to the formation of sp2 clusters of different sizes embedded in the sp3 carbon matrix.

Development of high bio‐content polypropylene composites with different industrial lignins

Sustainability, eco‐efficiency, pollution prevention, industrial ecology, and green chemistry are considering platform‐based approaches to the development of the next generation of products and processes. Recently, renewable alternatives to traditional petroleum‐derived plastics have motivated recent interest in bio‐based composite materials which can contribute to the reduction of the environmental footprint. Lignin is a complex and amorphous biopolymer with a high density of functional groups and high modulus, which makes it potentially promising for material applications. In this sense, lignin can potentially be employed to improve the performance of materials and an economical alternative to convert lignin into high value‐added materials. Two different types of Kraft lignin were incorporated into polypropylene to fabricate composites with high bio‐content. In this study, polypropylene, Kraft lignin, and coupling agent were subjected to reactive extrusion. The composites prepared by melt processing were compared in terms of morphological, mechanical, and thermal characterizations. The results revealed that the incorporation of lignin into polypropylene matrix resulted in composites with properties suitable for various industrial sectors, especially those in which mechanical and thermal properties are crucial, such as the replacement of engineering plastics and polypropylene mineral filled. As a result, this work provides an effective way of using lignin as a low‐cost bio‐renewable resource in the plastics industry.