Chemical Modification Strategies Research Articles

Tailoring Cyano Substitutions on Quinoxaline‐based Small‐Molecule Acceptors Enabling Enhanced Molecular Packing for High‐Performance Organic Solar Cells

AbstractCyanation is a common chemical modification strategy to fine‐tune the energy levels and molecular packing of organic semiconductors, especially materials used in organic solar cells (OSCs). Generally, cyanation is used to modify the end groups of high‐performance small‐molecule acceptors (SMAs). However, the cyanation strategy has not been investigated on the central backbone of SMAs, which could introduce stronger intermolecular interaction and enhance the π–π stacking for rapid charge transport. This paper, for the first time, reports a new cyanation strategy on the central benzo‐quinoxaline core and synthesizes two novel A‐DA'D‐A type SMAs, named BQx‐CN and BQx‐2CN, with mono‐ and di‐cyanide groups, respectively. Through tailoring the number of CN groups, the BQx‐CN‐based OSC exhibits the best device performance of 18.8%, which is significantly higher than the non‐cyano BQx‐based one. The reason for the superior performance of BQx‐CN‐based devices can be attributed to the fine‐tuned energy level, stronger packing, and ideal phase segregation, which lead to superior exciton dissociation, faster charge transport, and suppressed recombination, therefore the highest fill factor (FF) and power conversion efficiencies (PCE). The research demonstrates the effectiveness of the cyanation strategy on the central core of SMAs for enhanced molecular packing and better performance of OSCs.

Engineering peptide drug therapeutics through chemical conjugation and implication in clinics.

The development of peptide drugs has made tremendous progress in the past few decades because of the advancements in modification chemistry and analytical technologies. The novel-designed peptide drugs have been modified through various biochemical methods with improved diagnostic, therapeutic, and drug-delivery strategies. Researchers found it a helping hand to overcome the inherent limitations of peptides and bring continued advancements in their applications. Furthermore, the emergence of peptide-drug conjugates (PDCs)-utilizes target-oriented peptide moieties as a vehicle for cytotoxic payloads via conjugation with cleavable chemical agents, resulting in the key foundation of the new era of targeted peptide drugs. This review summarizes the various classifications of peptide drugs, suitable chemical modification strategies to improve the ADME (adsorption, distribution, metabolism, and excretion) features of peptide drugs, and recent (2015-early 2024) progress/achievements in peptide-based drug delivery systems as well as their fruitful implication in preclinical and clinical studies. Furthermore, we also summarized the brief description of other types of PDCs, including peptide-MOF conjugates and peptide-UCNP conjugates. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development and progress toward a bright future of novel peptide drugs.

Polyfluoroalkyl Tag Decoration Enables Significantly Enhanced Tumor Penetration Ability of a PTK7 Targeting Aptamer.

Aptamers are widely used molecular recognition tools in targeted therapy, but their ability to effectively penetrate deep into solid tumors remains a significant challenge, leading to suboptimal treatment efficacy. Here, we developed a polyfluoroalkyl (PFA) decoration strategy to enhance aptamer recognition, cell internalization, and solid tumor penetration. Our results indicate that PFA with around 11 fluorine atoms significantly improves aptamer internalization both in vitro and in vivo settings. However, we also observed that the use of PFA tags containing 19 and 23 fluorine atoms on aptamers resulted in nonspecific cell anchoring in control cell lines, affecting the specificity of aptamers. Overall, we found that using a chemical modification strategy could enhance the deep tumor penetration ability of aptamers and validate their effectiveness in vivo. This approach has significant practical applications in targeted drug delivery for cancer treatment.

Syntheses, Properties, and Applications of Aminated‐Starch: A Review

AbstractBecause aminated‐starch (AS) is an important chemical modification strategy of starch, much research on AS has been carried out. The present review summarizes the main synthetic strategies for AS. This review also outlines the changes in starch properties due to amination. The effects of amination on particle morphology, crystallinity, thermal properties, adhesion, and cytotoxicity are specifically reviewed. The main applications of AS are also detailed, including adsorbent and nano‐loaded particles.

Near‐infrared emitting metal halide materials: Luminescence design and applications

AbstractNear‐infrared (NIR) luminescent metal halide (LMH) materials have attracted great attention in various optoelectronic applications due to their low‐temperature solution‐processable synthesis, abundant crystallographic/electronic structures, and unique optoelectronic properties. However, some challenges still remain in their luminescence design, performance improvement, and application assignments. This review systematically summarizes the development of NIR LMHs through classifying NIR luminescent origins into four major categories: band‐edge emission, self‐trapped exciton (STE) emission, ion emission, and defect‐related emission. The luminescence mechanisms of different types of NIR LMHs are discussed in detail by analyzing typical examples. Reasonable strategies for designing and optimizing luminescence/optoelectronic properties of NIR LMHs are summarized, including bandgap engineering, self‐trapping state engineering, chemical composition modification, energy transfer, and other auxiliary strategies such as improvement of synthesis scheme and post‐processing. Furthermore, application prospects based on the optoelectronic devices are revealed, including phosphor‐converted light‐emitting diodes (LEDs), electroluminescent LEDs, photodetectors, solar cells, and x‐ray scintillators, as well as demonstrations of some related practical applications. Finally, the existing challenges and future perspectives on the development of NIR LMH materials are critically proposed. This review aims to provide general understanding and guidance for the design of high‐performance NIR LMHs materials.image

“Transforming enemy into friend” strategy-based stimuli responsive dual-drug liposomes for synergistic chemo-photodynamic therapy

Photodynamic therapy (PDT) induces aggravation of tumor hypoxia, which leads to worsening tumor invasiveness and metastasis. Combining hypoxia-responsive prodrugs with photosensitizers could transform “enemy” (tumor hypoxia) into “friend” (positive amplifier) to facilitate efficient activation of prodrugs. However, it remains challenging to develop a highly effective co-delivery nanoplatform due to the poor compatibility between vehicles and cargoes. Herein, we selected podophyllotoxin (PPT) as a model drug to synthesize hypoxia-responsive polyphenol prodrug (PAG). By introducing a chemical modification strategy, PAG and Chlorin e6 (Ce6) could be remotely co-encapsulated into liposomes (PAG/Ce6 LPs) at a synergistic ratio utilizing metal ions gradient. In vitro experiments demonstrated that PAG/Ce6 LPs could kill tumor cells through multiple pathways; i) generating reactive oxygen species (ROS) for direct cell killing; ii) consuming intracellular glutathione (GSH) to disturb intracellular redox homeostasis to induce tumor cell apoptosis. iii) aggravating hypoxia micro-environment to promote PPT release for chemotherapy. Furthermore, the excellent stability of PAG/Ce6 LPs guaranteed extended drug blood circulation time, enhanced tumor accumulation and improved anticancer efficacy. Additionally, PAG/Ce6 LPs kept fluorescence quench in circulation and specifically recovered at the tumor site, avoiding the obstacle of phototoxicity. Such a co-delivery nanoplatform, integrating hypoxia-responsive polyphenol prodrugs and photosensitizer into one nanocarrier, provides new insight into solving the challenges of chemo-photodynamic therapy.

Oligonucleotide therapeutics and their chemical modification strategies for clinical applications

Oligonucleotide therapeutics and their chemical modification strategies for clinical applications

Surface modification strategies of 304 austenitic stainless steel plate with different micromorphology and composition for improved mechanical interlocking and chemical bonding in metal–epoxy joints

304 austenitic stainless-steel (SS) strip-based carbon fiber metal laminates (CFMLs) have raised significant concerns, in terms of their mechanical performance. On top of that, the hybrid laminates’ interlamination performance is vital in regulating their failure patterns. Along these lines, in this work, SS strips with regulatable micromorphology and composition were obtained by using physical and chemical surface modification strategies, including polishing, acid etching, anodization, and thermal treatment. The shear strength of the treated-SS/epoxy single lap joints (two treated-SS strips bonded by the epoxy resin via hot curing process) was systematically explored, and the origins of the enhancement mechanism were attributed to the resulting surface microstructure, as well as the possible chemical reactions between the treated surface and the curing agent. The etching-anodizing-thermally treated-SS (EAT-SS)/epoxy joint exhibited the maximum shear strength (16.04 MPa) and work of fracture (5.85 kJ·m−2) due to the substantial cohesive failure pattern of the epoxy. The encouraging enhancement was mainly attributed to the synergistic effect of the micro-annular pit and the nanoporous array structure of the EAT-SS surface. These effects induced a significant mechanical interlock and a plausible chemical reaction at the interface, which led to improved bonding strength between the epoxy and treated-SS surface. Overall, in this work, it was demonstrated that the combination of the anodization and thermal treatment can effectively improve the interlamination bonding properties between the SS strip and the epoxy resin due to the combination effect of mechanical interlocking and chemical bonding.

68Ga-Labeled TMTP1 Modified with d-Amino Acid for Positron Emission Tomography Diagnosis of Highly Metastatic Hepatocellular Carcinoma.

TMTP1 (NVVRQ) has been proven to selectively target various highly metastatic tumor cells. Nonetheless, existing TMTP1 probes encounter challenges such as rapid blood clearance, limited tumor uptake, and inadequate suitability for therapeutic interventions. To overcome these constraints, we designed and synthesized eight peptide probes, employing innovative chemical modification strategies involving d-amino acid modification and retro-inverso isomerization. Notably, [68Ga]TV2 exhibited particularly impressive performance, displaying an 88.88, 76.90, and 90.32% improvement in uptake at 15, 30, and 60 min, respectively, while maintaining a high target-to-nontarget ratio. Further research has demonstrated that [68Ga]TV2 also exhibits remarkable diagnostic potential for detecting in situ microtumors in the liver. The results suggest that through the implementation of innovative chemical modification strategies, we successfully developed a peptide precursor, NOTA-G-NVvRQ, with specific affinity for highly metastatic tumors, enhanced in vivo pharmacokinetic profile, and heightened stability in vivo, rendering it well suited for prospective investigations in combination therapy studies.

Structural Heredity in Catalysis: CO2 Self‐Selective CeO2 Nanocrystals for Efficient Photothermal CO2 Hydrogenation to Methane

AbstractThe chemical inertness of CO2 molecules makes their adsorption and activation on a catalyst surface one of the key challenges in recycling CO2 into chemical fuels. However, the traditional template synthesis and chemical modification strategies used to tackle this problem face severe structural collapse and modifier deactivation issues during the often‐needed post‐processing procedure. Herein, a CO2 self‐selective hydrothermal growth strategy is proposed for the synthesis of CeO2 octahedral nanocrystals that participate in strong physicochemical interactions with CO2 molecules. The intense affinity for CO2 molecules persists during successive high‐temperature treatments required for Ni deposition. This demonstrates the excellent structural heredity of the CO2 self‐selective CeO2 nanocrystals, which leads to an outstanding photothermal CH4 productivity exceeding 9 mmol h‐1 mcat‐2 and an impressive selectivity of >99%. The excellent performance is correlated with the abundant oxygen vacancies and hydroxyl species on the CeO2 surface, which create many frustrated Lewis‐pair active sites, and the strong interaction between Ni and CeO2 that promotes the dissociation of H2 molecules and the spillover of H atoms, thereby greatly benefitting the photothermal CO2 methanation reaction. This self‐selective hydrothermal growth strategy represents a new pathway for the development of effective catalysts for targeted chemical reactions.

Tuning the electronic and optical properties of small organic acenedithiophene molecular crystals for photovoltaic applications: First principles calculations.

Periodic density functional theory was employed to investigate the impact of chemical modifications on the properties of π-conjugated acenedithiophene molecular crystals. Here, we highlight the importance of the β-methylthionation effect, the position of the sulfur atoms of the thiacycle group and their size, and the number of central benzene rings in the chemical modification strategy. Our results show that the introduction of the methylthio groups at the β-positions of the thiophene and the additional benzene ring at the center of the BDT crystal structure are a promising strategy to improve the performance of organic semiconductors, as observed experimentally. We found that β-MT-ADT exhibits large charge carrier mobility, which is in good agreement with the experimental results and comparable to that of rubrene. In addition, the electronic and optical properties of these ambipolar materials suggest promising performances with β-MT-ADT > ADT >β-MT-NDT > NDT > BEDT-BDT >β-MT-BDT > BDT. Moreover, functionalization with thiacycle-fused sulfur atoms of different sizes and numbers improve the properties of BDT but is still less efficient than the methylthionation effect. Overall, our findings suggest a promising molecular modification strategy for possibly high performance ambipolar organic semiconducting materials.

Designing high-performance quasi-symmetrical solid oxide cells with a facile chemical modification strategy for Sr2Fe2−xWxO6−δ ferrites electrodes with in situ exsolution of nanoparticles

The chemical modification of perovskites is one of the most effective design strategies for electrode materials for solid oxide cells. In this work, the tungsten doping in Sr2Fe2−xWxO6−δ shows a significant impact on their physicochemical properties, and it leads to a substantial change of electrochemical properties in the air and reducing conditions, with Sr2Fe1.8W0.2O6−δ (Rp = 0.06 Ω cm2 at 800 °C stable for 100 h in air) and Sr2Fe1.6W0.4O6−δ (Rp = 0.56 Ω cm2 at 800 °C over 100 h in 5 vol% H2/Ar) being the best air and fuel electrode candidates, respectively. We have proposed an attractive design of high-performance quasi-symmetrical solid oxide cells with 80%Sr2Fe1.8W0.2O6−δ+20%GDC | LSGM | 80%Sr2Fe1.6W0.4O6−δ+20%GDC, demonstrating excellent power outputs (874 mW cm−2 at 850 °C in wet H2) and good current density of 743 mA cm−2 at 1.5 V in electrolysis mode at 750 °C. A good performance of 451 mW cm−2 was also recorded in wet CH4 at 800 °C. The in situ exsolved metallic iron nanoparticles decorated on the Sr2Fe1.6W0.4O6−δ anode contribute to the excellent electrochemical performance of cells. This study provides a successful scenario for designing high-performance symmetrical solid oxide cells with a facile chemical modification strategy for ferrites electrodes with in situ exsolution of nanoparticles.

Dispersion of reduced nanodiamond and its application in lubrication

Nanodiamonds (ND) possess remarkable properties derived from both bulk diamonds and nanoparticles. However, their full potential has been impeded by spontaneous particle agglomeration caused by high surface energy. To address this, we have developed a facile, cost-effective, and contaminant-free method to homogenize the ND surface by incorporating sodium borohydride (NaBH4) reduction in a mechanochemical process. Throughout this study, we extensively investigated various influencing factors, such as grinding time, reducing agent ratio, and surface charge, to successfully modify the ND surface. The results demonstrated that the introduction of hydroxyl functional groups significantly improved dispersibility and enabled the re-dispersion of modified ND into the water and other common solvents, achieving particle sizes below 200 nm. Notably, our reduced ND exhibited potential as an additive in lubricating oil, contributing to energy saving and emission reduction. For instance, when 0.02% reduced ND was supplemented into PAO6 lubricant oil, it cannot only reduce the oil consumption by 7.72% but also significantly lower CO, HC, and NOX emissions by 20.2% and 12.7%, respectively. This suggests that the proposed strategy for ND surface chemical modification can enhance colloidal stability and find practical applications in the lubricating oil industry.

Synergistic Use of All-Acceptor Strategies for the Preparation of an Organic Semiconductor and the Realization of High Electron Transport Properties in Organic Field-Effect Transistors.

The development of n-type organic semiconductor materials for transporting electrons as part of logic circuits is equally important to the development of p-type materials for transporting holes. Currently, progress in research on n-type materials is relatively backward, and the number of polymers with high electron mobility is limited. As the core component of the organic field-effect transistor (OFET), the rational design and judicious selection of the structure of organic semiconductor materials are crucial to enhance the performance of devices. A novel conjugated copolymer with an all-acceptor structure was synthesized based on an effective chemical structure modification and design strategy. PDPPTT-2Tz was obtained by the Stille coupling of the DPPTT monomer with 2Tz-SnMe3, which features high molecular weight and thermal stability. The low-lying lowest unoccupied molecular orbital (LUMO) energy level of the copolymer was attributed to the introduction of electron-deficient bithiazole. DFT calculations revealed that this material is highly planar. The effect of modulation from a donor-acceptor to acceptor-acceptor structure on the improvement of electron mobility was significant, which showed a maximum value of 1.29 cm2 V-1 s-1 and an average value of 0.81 cm2 V-1 s-1 for electron mobility in BGBC-based OFET devices. Our results demonstrate that DPP-based polymers can be used not only as excellent p-type materials but also as promising n-type materials.

Cu(Ⅱ) and Co(Ⅱ) complexes decorated ammonium polyphosphate as co-curing agents on improving fire safety and mechanical properties of epoxy-based building coatings

Epoxy resin (EP) is widely used as an organic coating in the field of building materials (such as steel and timber). However, it’s high flammability and smoke release in fires further hinder its application in construction. Here, Cu(II) and Co(II) complexes decorated ammonium polyphosphates (BAPP@Cu and BAPP@Co) were synthesized by a facile strategy of chemical surface modification and used as multifunctional additives to enhance various properties of epoxy coatings. It has been found that both BAPP@Cu and BAPP@Co as co-curing agents not only promote the curing reaction of EP but also enhance the interfacial compatibility between the filler and the epoxy matrix. In addition, both BAPP@Cu and BAPP@Co endow EP with enhanced mechanical performance and heat insulation compared to pristine ammonium polyphosphate (APP). More importantly, both BAPP@Cu and BAPP@Co impart excellent fire safety to EP coatings. The peak heat release rate (pHRR) and peak CO production rate (pCO) of EP-6 %BAPP@Cu are decreased by 35.6% and 46.2%, respectively, compared to virgin EP. Similarly, EP-6 %BAPP@Co exhibits high fire performance, with a 57.7% reduction in pHRR and a 62.9% reduction in pCO, respectively, in comparison to virgin EP. This work reports a new strategy for the chemical modification of APP by metal complexes and provides a new perspective for the application of building coating materials.

Newly Synthesized 3-Indolyl Furanoid Inhibits Matrix Metalloproteinase-9 Activity and Prevents Nonsteroidal Anti-inflammatory Drug-Induced Gastric Ulceration.

Indomethacin, a known nonsteroidal anti-inflammatory drug (NSAID) induces gastric inflammation, causing degradation of the extracellular matrix by specific matrix metalloproteinases (MMPs). We investigated the antiulcer efficacy of 3-indolyl furanoids (3g and 3c, i.e., methoxy substitution at 4- and 5-positions of the indole ring, respectively), derived from indomethacin. Interestingly, 3g protected against indomethacin-induced gastropathy in vivo by inhibiting MMP-9. Our work established a chemical modification strategy for the development of safer NSAIDs. Moreover, in vitro and in silico studies confirmed that 3g inhibited MMP-9 activity with an IC50 value of 50 μM by binding to the catalytic cleft of MMP-9, leading to ulcer prevention. Pharmacokinetics was presented as the mean concentration-time profile in the rat plasma, and the extraction efficiency was greater than 70%, showing a Cmax of 104.48 μg/mL after 6.0 h (tmax) treatment with half-life and area under the curve being 7.0 h and 1273.8 h μg/mL, respectively, indicating the higher antiulcer potency of 3g.

Chemical modification strategies for the control of graphene localization in PS/PMMA blend

This work concerns the nanoparticles localization control in a PMMA/PS polymer blend. In this article, a complete study was made on the poly(methylmethacrylate)/polystyrene/graphene (PMMA/PS/graphene) polymer blend nanocomposites performed by a melt-blending process at PMMA/PS equal proportion (50/50). Graphene nanoparticles were modified via different chemical modification strategies such as Hummers’ oxidation (GOxH), hydrazine reduction (GOxH-r2) and copolymer functionalization by a “grafting onto” method. The evolution of graphene nanoparticles morphology, chemical structure during the melt-blending process were investigated to explain their final localization. Considering GOxH nanoparticles, the in-situ reduction during the process was proved by Raman spectroscopy, FTIR and XRD. The stability of the copolymer grafting was also confirmed after melt-compounding by Py-GC/MS. The predicted localization by thermodynamics was compared to the real localization determined by STEM images. Functionalized graphene (GOxN-PMMA, GOxH-PMMA, GOxH-r2-PMMA, GOxH-r2-PMMA-r1) showed a transfer from PS to PMMA, whereas non-functionalized nanoparticles (G, GOxH, GOxH-r2) remain in PS. Graphene migration mechanisms and polymer blend microstructures were also investigated. Graphene nanoparticles interaction with polymer matrices and their impact on viscosity was studied by rheology to assess the final microstructure of the polymer blend nanocomposites.

Solvent-free functionalization of sawdust with quaternary ammonium groups: Application to the biosorption of two anionic dyes

The improvement of sawdust reactivity through simple chemical modification strategies represent an interesting method to extend the field of application or improve the natural performances of this abundant and available waste. In this work, sawdust was modified with Glycidyltrimethylammonium chloride (GTAC), an organic compound bearing a quaternary ammonium group. The objective was to obtain a modified sawdust with a permanent cationic charge. The modification of the material was confirmed by solid state 13C NMR and FTIR spectroscopy. The anion exchange capacity of modified sawdust (Sa-G) was demonstrated by the ability of sawdust to exclusively adsorb cations before modification and anions after modification. This anionic exchange property was applied for the adsorption of two anionic dyes (Procion Red MX-5B (PR) and Evans Blue (EB)). Generally, the material was more effective in acidic conditions due to the acid-base properties of sawdust. Compared to EB, the less charged and smaller PR adsorbs more quantitatively on the material and with faster kinetics (Equilibrium reached after only 30 min, while more than 24 h were needed in the case of EB). Thermodynamic study also reveals an exothermic process in the case of PR and endothermic in the case of EB. Under optimal conditions, the maximum adsorption capacities were 121.8 μmol g−1 for PR and 103.1 μmol g−1 for EB. Desorption tests showed that the material can be recycled by desorption of dyes in 0.1 M sodium hydroxide solution. After 5 adsorption-desorption cycles performance losses of only 15% for EB and 30% for PR were recorded.

Hydrophilic Modification Strategies to Enhance the Surface Biocompatibility of Poly(dimethylsiloxane)‐Based Biomaterials for Medical Applications

AbstractPoly(dimethylsiloxane) (PDMS) has been widely employed in biomedical disciplines due to its several advantages, including biocompatibility, nontoxicity, and low‐cost preparation. However, the intrinsic hydrophobicity of this material encourages biofouling and reduces cell regulation capacity, thereby limiting its biomedical applicability. The purpose of this study is to explore the surface modification and functionalization of PDMS and PDMS‐based biomaterials to improve their properties for biomedical applications. The content of this review is organized based on physical and chemical surface modification strategies to improve surface hydrophilicity to enhance antibiofouling and the regulation of immunomodulation and cell modulation on the surface of PDMS and PDMS‐based biomaterials. Future developments in this area are also discussed.

A Combination Strategy of Multidrug-Sensitive Budding Yeast and Chemical Modifications Enabling to Find a New Overlooked Antifungal Compound, Sakurafusariene, from In-House Fractionated Library.

In this report, we disclose our discovery of a new antifungal natural product, sakurafusariene (1), from an in-house fractionated library of the culture broth of Fusarium sp. FKI-7550 strain by using a combination strategy of multidrug-sensitive yeast and chemical modification. Throughout our investigation, we encountered challenges in the isolation of natural product 1. A chemical modification strategy via alkylation of 1 allowed for removal of the impurities enabling us to elucidate the structure of 1. Furthermore, we synthesized ester derivatives using a method inspired by the isolation study of 1, which gave us valuable information to understand a preliminary structure-activity relationship against Pyricularia oryzae growth inhibitory activity.