We report a 3D-printed graphene-silver nanocomposite (Gr-Ag NC) electrode for selective electrochemical detection of multiple analytes such as dopamine, lead ions (Pb2+), hydroquinone, and catechol in environmental and clinical samples. A conductive PLA-based cylindrical electrode was fabricated via fused deposition modeling (FDM) followed by internal modification with Gr-Ag NC. The NC was characterized using SEM, HR-TEM, UV, and FTIR to confirm the size, shape, formation, and dispersion of AgNPs on Gr sheets. The electrode exhibited an excellent electrochemical behavior, enhanced surface area (0.24 cm2), and high reproducibility (RSD < 4%) in differential pulse voltammetry and cyclic voltammetry. The electrochemical sensor demonstrated wide linear ranges for determination of dopamine (0.5-10 μM), Pb2+ (0.04-1.04 μM), hydroquinone, and catechol (10-60 μM), with limits of detection of 0.2, 0.02, 3.0, and 1.0 μM, respectively. The recovery study results for urine, river, pond, and wastewater from 90.0% to 98.0% confirmed the accuracy and reliability of the electrode used for electrochemical measurements. Additionally, the electrode exhibited long-term stability over 60 days and showed robust intraday and interday reproducibility. This study offers a scalable and cost-effective system for development of electrochemical sensors for detection of multichemical species from environmental and clinical samples.
{"title":"3D-Printed PLA-Graphene-Silver Nanocomposite Electrode for Electrochemical Sensing of Multiple Analytes.","authors":"Ankita Tejwani,Kamlesh Shrivas,Khushali Tandey,Arun Kumar Patel, Tikeshwari,Anuradha Sharma","doi":"10.1021/acs.langmuir.5c04141","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04141","url":null,"abstract":"We report a 3D-printed graphene-silver nanocomposite (Gr-Ag NC) electrode for selective electrochemical detection of multiple analytes such as dopamine, lead ions (Pb2+), hydroquinone, and catechol in environmental and clinical samples. A conductive PLA-based cylindrical electrode was fabricated via fused deposition modeling (FDM) followed by internal modification with Gr-Ag NC. The NC was characterized using SEM, HR-TEM, UV, and FTIR to confirm the size, shape, formation, and dispersion of AgNPs on Gr sheets. The electrode exhibited an excellent electrochemical behavior, enhanced surface area (0.24 cm2), and high reproducibility (RSD < 4%) in differential pulse voltammetry and cyclic voltammetry. The electrochemical sensor demonstrated wide linear ranges for determination of dopamine (0.5-10 μM), Pb2+ (0.04-1.04 μM), hydroquinone, and catechol (10-60 μM), with limits of detection of 0.2, 0.02, 3.0, and 1.0 μM, respectively. The recovery study results for urine, river, pond, and wastewater from 90.0% to 98.0% confirmed the accuracy and reliability of the electrode used for electrochemical measurements. Additionally, the electrode exhibited long-term stability over 60 days and showed robust intraday and interday reproducibility. This study offers a scalable and cost-effective system for development of electrochemical sensors for detection of multichemical species from environmental and clinical samples.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"13 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145710886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-09DOI: 10.1021/acs.langmuir.5c04508
Isaí Barboza-Ramos, Yan Zhao, Han Sun, Zhiliang Li, Kirk S. Schanze
Designing ordered nanoscale molecular assemblies has been inspired by natural occurring supramolecular structures in which dynamic noncovalent interactions play a key role in the nanotemplating process. Herein, we describe the self-assembly and quenching properties of a series of phosphonium-substituted poly(phenylene ethynylene) (PPE)-based conjugated polyelectrolytes (CPEs) in the presence of nucleotide phosphates. The study includes a detailed analysis of the changes in the absorption and fluorescence induced by the addition of nucleotides (AMP, ADP, ATP, GTP, and UTP). Notably, the polymer chains of PPh-4-3C were observed to undergo self-assembly upon interacting with ATP, resulting in a chiral, optically active supramolecular assembly with the spectroscopic signature of a J-aggregate. The supramolecular assembly derives from the intermolecular interactions between PPh-4-3C and ATP as confirmed by steady-state absorption, fluorescence, and circular dichroism spectroscopy in methanol solutions. The observations confirm that PPh-4-3C as a novel phosphonium-bearing cationic conjugated polymer forms optically active J-type aggregates in the presence of ATP. Interestingly, microscopy analysis techniques confirm the self-assembly of the PPh-4-3C/ATP system into capsule-like nanostructures.
{"title":"Nucleotide-Induced Supramolecular Assembly of Phosphonium-Containing Conjugated Polyelectrolytes","authors":"Isaí Barboza-Ramos, Yan Zhao, Han Sun, Zhiliang Li, Kirk S. Schanze","doi":"10.1021/acs.langmuir.5c04508","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04508","url":null,"abstract":"Designing ordered nanoscale molecular assemblies has been inspired by natural occurring supramolecular structures in which dynamic noncovalent interactions play a key role in the nanotemplating process. Herein, we describe the self-assembly and quenching properties of a series of phosphonium-substituted poly(phenylene ethynylene) (PPE)-based conjugated polyelectrolytes (CPEs) in the presence of nucleotide phosphates. The study includes a detailed analysis of the changes in the absorption and fluorescence induced by the addition of nucleotides (AMP, ADP, ATP, GTP, and UTP). Notably, the polymer chains of <b>PPh-4-3C</b> were observed to undergo self-assembly upon interacting with ATP, resulting in a chiral, optically active supramolecular assembly with the spectroscopic signature of a J-aggregate. The supramolecular assembly derives from the intermolecular interactions between <b>PPh-4-3C</b> and ATP as confirmed by steady-state absorption, fluorescence, and circular dichroism spectroscopy in methanol solutions. The observations confirm that <b>PPh-4-3C</b> as a novel phosphonium-bearing cationic conjugated polymer forms optically active J-type aggregates in the presence of ATP. Interestingly, microscopy analysis techniques confirm the self-assembly of the <b>PPh-4-3C</b>/ATP system into capsule-like nanostructures.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"58 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The devastating occurrence of antibiotic resistance arising from the surrounding environment, such as in healthcare facilities, has posed global threats to public health, urging a continuous search for safe and effective antibacterial agents. Here, the adjuvant activity center of hemin in conjunction with the traditional antibiotic of ampicillin was successfully encapsulated into a three-dimensional macromolecular framework of bovine serum albumin (BSA) to form hemin-BSA-ampicillin nanoparticles (HBA NPs) via a straightforward desolvation process. Based on the robust peroxidase-like activity of the obtained HBA NPs, a significant quantity of hydroxyl radicals (•OH) was generated via the Fenton-like reaction. As an electrophilic species, •OH may not only facilitate the oxidation of organic substances, leading to observable color reaction, but also effectively inactivate pathogens, including drug-resistant bacteria and viruses, through structural decomposition. Compared to the sole antibacterial effect of ampicillin, HBA NPs exhibited markedly superior antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the formed protein coating on the nanoparticles contributed significantly to the desirable biocompatibility of the obtained nanocomposite. Therefore, the easily prepared, highly biocompatible, and antimicrobial HBA NPs provided a prototype of protein-based antibiotic adjuvants using peroxidase-like nanomaterials with promising therapeutic potential to tackle emerging drug-resistant infectious microbes.
{"title":"Desolvation Synthesis of Peroxidase-like Bovine Serum Albumin-Based Nanoparticles as a Potent Antibiotic Adjuvant To Tackle Drug-Resistant Bacteria.","authors":"Guannan Le,Henghui Li,Ling Cai,Xinyi Zhu,Zhijiang Ji,Changcai Zhu,Yanqiang Huang,Jin Chen","doi":"10.1021/acs.langmuir.5c04404","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04404","url":null,"abstract":"The devastating occurrence of antibiotic resistance arising from the surrounding environment, such as in healthcare facilities, has posed global threats to public health, urging a continuous search for safe and effective antibacterial agents. Here, the adjuvant activity center of hemin in conjunction with the traditional antibiotic of ampicillin was successfully encapsulated into a three-dimensional macromolecular framework of bovine serum albumin (BSA) to form hemin-BSA-ampicillin nanoparticles (HBA NPs) via a straightforward desolvation process. Based on the robust peroxidase-like activity of the obtained HBA NPs, a significant quantity of hydroxyl radicals (•OH) was generated via the Fenton-like reaction. As an electrophilic species, •OH may not only facilitate the oxidation of organic substances, leading to observable color reaction, but also effectively inactivate pathogens, including drug-resistant bacteria and viruses, through structural decomposition. Compared to the sole antibacterial effect of ampicillin, HBA NPs exhibited markedly superior antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the formed protein coating on the nanoparticles contributed significantly to the desirable biocompatibility of the obtained nanocomposite. Therefore, the easily prepared, highly biocompatible, and antimicrobial HBA NPs provided a prototype of protein-based antibiotic adjuvants using peroxidase-like nanomaterials with promising therapeutic potential to tackle emerging drug-resistant infectious microbes.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"26 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rapid development of modern society and the chemical industry, the demand for hydroxylamine (NH2OH) has expanded significantly across diverse fields. However, its conventional synthesis remains challenged by severe pollution and intensive resource consumption. Building upon the experimentally realized Fe@N4 structure, we propose a ligand coordination strategy to module the electronic structure of iron single-atom catalysts via 15 axial ligands (-F, -Cl, -Br, -I, -N, -O, -OH, -OOH, -CH, -CH2, -CH3, -NH2, -SH, -CN, -SCH3), aiming to enhance the electrocatalytic reduction of nitric oxide (NO) to NH2OH. Among these, 13 catalysts effectively suppress hydrogen evolution reactions and the generation of undesired byproducts such as NH3 and N2O/N2. Notably, the -CH2 ligand significantly alters the local electronic environment of the active site, enabling the activation of NO molecules through an electronic "accept-donate" mechanism. This modulation enhances both the activity and selectivity for NO reduction, ultimately leading to a spontaneous, exothermic conversion of NO to NH2OH. This work theoretically proposes a strategy whereby axial coordination can enhance the catalytic reactivity of single-atom catalysts.
{"title":"Axial Coordination of Iron Single-Atom Catalysts on Defective Graphene for Electrocatalytic Conversion of Nitric Oxide to Hydroxylamine: A Theoretical Investigation.","authors":"Jianhong Hu,Wenqi Ruan,Qixiang Bai,Wei Lin,Xiangyu Guo,Kaining Ding","doi":"10.1021/acs.langmuir.5c03697","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c03697","url":null,"abstract":"With the rapid development of modern society and the chemical industry, the demand for hydroxylamine (NH2OH) has expanded significantly across diverse fields. However, its conventional synthesis remains challenged by severe pollution and intensive resource consumption. Building upon the experimentally realized Fe@N4 structure, we propose a ligand coordination strategy to module the electronic structure of iron single-atom catalysts via 15 axial ligands (-F, -Cl, -Br, -I, -N, -O, -OH, -OOH, -CH, -CH2, -CH3, -NH2, -SH, -CN, -SCH3), aiming to enhance the electrocatalytic reduction of nitric oxide (NO) to NH2OH. Among these, 13 catalysts effectively suppress hydrogen evolution reactions and the generation of undesired byproducts such as NH3 and N2O/N2. Notably, the -CH2 ligand significantly alters the local electronic environment of the active site, enabling the activation of NO molecules through an electronic \"accept-donate\" mechanism. This modulation enhances both the activity and selectivity for NO reduction, ultimately leading to a spontaneous, exothermic conversion of NO to NH2OH. This work theoretically proposes a strategy whereby axial coordination can enhance the catalytic reactivity of single-atom catalysts.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"33 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the effects of constructing a metal-phenol quinone network under thermomechanical processing on chitosan-silk peptide (CS-SP) composite films by varying tannic acid (TA) concentration and metal oxide types. The process was inspired by the hardening mechanism of insect cuticles. Upon TA addition, hydrogen bonding formed between TA and CS-SP, while covalent interactions occurred between oxidized quinone groups of TA and amino groups in CS-SP. Copper oxide and zinc oxide were found to promote quinone-mediated cross-linking. The mechanical properties of the composite films were significantly enhanced with TA addition, reaching a tensile strength of up to 43.5 MPa at 3% TA. The incorporation of copper oxide and zinc oxide further increased the tensile strength to 57.7 MPa and the hardness to 58.17 HD. Moreover, the combination of TA and metal oxides improved the antibacterial activity of the films against both S. aureus and E. coli. This work offers a scalable strategy for developing high-strength natural polymer-based composite films with promising applications in agricultural and food chemistry.
{"title":"Effect of Metal-Phenolic Quinone Network on the Performance of Thermomechanical Processed Chitosan-Silk Peptide Biomimetic Films: Improved Mechanical and Antibacterial Properties.","authors":"Linhua Zhang,Jiajia Qin,Linghan Meng,Xiao Feng,Weiwei Cheng,Chengcheng Gao,Zhenjiong Wang,Xiaozhi Tang","doi":"10.1021/acs.langmuir.5c04755","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04755","url":null,"abstract":"This study investigates the effects of constructing a metal-phenol quinone network under thermomechanical processing on chitosan-silk peptide (CS-SP) composite films by varying tannic acid (TA) concentration and metal oxide types. The process was inspired by the hardening mechanism of insect cuticles. Upon TA addition, hydrogen bonding formed between TA and CS-SP, while covalent interactions occurred between oxidized quinone groups of TA and amino groups in CS-SP. Copper oxide and zinc oxide were found to promote quinone-mediated cross-linking. The mechanical properties of the composite films were significantly enhanced with TA addition, reaching a tensile strength of up to 43.5 MPa at 3% TA. The incorporation of copper oxide and zinc oxide further increased the tensile strength to 57.7 MPa and the hardness to 58.17 HD. Moreover, the combination of TA and metal oxides improved the antibacterial activity of the films against both S. aureus and E. coli. This work offers a scalable strategy for developing high-strength natural polymer-based composite films with promising applications in agricultural and food chemistry.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"11 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research leverages the minor iron oxides and carbon contained in Bayan Obo tailings (BOT) and coal gangue for the synthesis of magnetic zeolite NaA, which was subsequently applied to recover and separate rare earth elements (REEs) from Nd-Fe-B passivation solutions. To control the synthesis conditions of the magnetic zeolite, the effects of different raw material ratios, silicon/aluminum ratios, alkali fusion temperature, and hydrothermal reaction time on the phase composition, microstructure, and adsorption properties were investigated. The results show that magnetic NaA zeolite with a complete crystal structure can be synthesized when roasting is performed at 750 °C for 120 min, followed by a hydrothermal treatment at 75 °C for 6 h. Adsorption of Nd3+ and Pr3+ from aqueous solutions by the BOT-coal gangue-based magnetic zeolite conforms to the Langmuir isotherm model and the pseudo-first-order kinetic equation. The adsorption rate is controlled by the adsorption resistance between particles. The saturated adsorption capacities of the zeolite for Nd3+ and Pr3+ reached 350 mg/g and 156 mg/g, respectively. After 5 cycles, the adsorption efficiency remains above 89.2%, confirming its excellent regeneration capability. When RE3+ and Cr3+ coexist, rare earth ions are preferentially adsorbed. This characteristic enables the separation of RE3+ and Cr3+ in Nd-Fe-B electroplating wastewater. Dynamic adsorption experiments demonstrated that under conditions of 4 g of magnetic zeolite, an initial RE3+ concentration of 100 mg/L, and a flow rate of 8 mL/min, nearly all rare earth ions were completely adsorbed within the first 4 h.
{"title":"Magnetic NaA Zeolites Synthesized from Dual Solid Wastes Enables Selective Efficient Recovery of Rare Earth Ions from Neodymium Iron Boron Electroplating Wastewater.","authors":"Pengyu Wang,Chunlin Gao,Xiaoling Duan,Yuxin Chen,Kexuan Shen,Jun Peng,Zhanfeng Yang,Shengli An,Zhiwei Chen,Chenxia Qiao","doi":"10.1021/acs.langmuir.5c04634","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04634","url":null,"abstract":"This research leverages the minor iron oxides and carbon contained in Bayan Obo tailings (BOT) and coal gangue for the synthesis of magnetic zeolite NaA, which was subsequently applied to recover and separate rare earth elements (REEs) from Nd-Fe-B passivation solutions. To control the synthesis conditions of the magnetic zeolite, the effects of different raw material ratios, silicon/aluminum ratios, alkali fusion temperature, and hydrothermal reaction time on the phase composition, microstructure, and adsorption properties were investigated. The results show that magnetic NaA zeolite with a complete crystal structure can be synthesized when roasting is performed at 750 °C for 120 min, followed by a hydrothermal treatment at 75 °C for 6 h. Adsorption of Nd3+ and Pr3+ from aqueous solutions by the BOT-coal gangue-based magnetic zeolite conforms to the Langmuir isotherm model and the pseudo-first-order kinetic equation. The adsorption rate is controlled by the adsorption resistance between particles. The saturated adsorption capacities of the zeolite for Nd3+ and Pr3+ reached 350 mg/g and 156 mg/g, respectively. After 5 cycles, the adsorption efficiency remains above 89.2%, confirming its excellent regeneration capability. When RE3+ and Cr3+ coexist, rare earth ions are preferentially adsorbed. This characteristic enables the separation of RE3+ and Cr3+ in Nd-Fe-B electroplating wastewater. Dynamic adsorption experiments demonstrated that under conditions of 4 g of magnetic zeolite, an initial RE3+ concentration of 100 mg/L, and a flow rate of 8 mL/min, nearly all rare earth ions were completely adsorbed within the first 4 h.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"30 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1021/acs.langmuir.5c04937
Wai Yuen Leung,Xi Liu,Yuhao Xu,Xiangchun Xuan
Electroosmotic flow is commonly used with other electrokinetic phenomena to manipulate aqueous samples in micro/nanofluidic devices. However, most studies of electroosmosis have been focused upon Newtonian fluids, although many chemical and biological samples are complex fluids with shear-thinning and viscoelastic characteristics. These rheological properties have been demonstrated to enhance electroosmotic pumping, mixing, etc., for which a fundamental understanding of electroosmotic velocity is crucial. We develop here a numerical model to understand and predict the experimentally measured electroosmotic velocity of xanthan gum solutions in a rectangular microchannel from our previous paper (J. Bentor et al., Langmuir 2024, 40, 20113-20119). This model couples interfacial electrokinetics with shear-thinning rheology by considering a polymer depletion layer (PDL), which is a Newtonian fluid free of polymer due to the polymer-wall interactions, adjacent to each channel wall and a power-law fluid in the bulk. It predicts with good accuracy the experimental electroosmotic velocity in xanthan gum solutions with varying polymer and buffer concentrations across the tested electric fields. The only fitting parameter is PDL thickness, which decreases with the increasing polymer or buffer concentration but is independent of the electric field magnitude. The PDL to electricdouble-layer thickness ratio is found to play a critical role in understanding the electric field nonlinearity of the electroosmotic velocity.
在微/纳米流体装置中，电渗透流动通常与其他电动力学现象一起用于操纵含水样品。然而，尽管许多化学和生物样品是具有剪切变薄和粘弹性特性的复杂流体，但大多数电渗透研究都集中在牛顿流体上。这些流变特性已被证明可以增强电渗透泵送、混合等，因此对电渗透速度的基本理解是至关重要的。我们在此建立了一个数值模型来理解和预测我们之前的论文（J. Bentor et al., Langmuir 2024, 40, 2013 -20119）中实验测量的矩形微通道中黄原胶溶液的电渗透速度。该模型通过考虑聚合物耗损层（PDL）将界面动力学与剪切变薄流变学耦合在一起。PDL是一种牛顿流体，由于聚合物与管壁的相互作用而不含聚合物，邻近每个管壁，在整体中为幂律流体。它可以很准确地预测黄原胶溶液在不同聚合物和缓冲液浓度下的实验电渗透速度。唯一的拟合参数是PDL厚度，它随聚合物或缓冲液浓度的增加而减小，但与电场大小无关。发现PDL与电双层厚度比对于理解电渗透速度的电场非线性起着关键作用。
{"title":"Electroosmotic Flow of Shear-Thinning Xanthan Gum Solutions in a Rectangular Microchannel.","authors":"Wai Yuen Leung,Xi Liu,Yuhao Xu,Xiangchun Xuan","doi":"10.1021/acs.langmuir.5c04937","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04937","url":null,"abstract":"Electroosmotic flow is commonly used with other electrokinetic phenomena to manipulate aqueous samples in micro/nanofluidic devices. However, most studies of electroosmosis have been focused upon Newtonian fluids, although many chemical and biological samples are complex fluids with shear-thinning and viscoelastic characteristics. These rheological properties have been demonstrated to enhance electroosmotic pumping, mixing, etc., for which a fundamental understanding of electroosmotic velocity is crucial. We develop here a numerical model to understand and predict the experimentally measured electroosmotic velocity of xanthan gum solutions in a rectangular microchannel from our previous paper (J. Bentor et al., Langmuir 2024, 40, 20113-20119). This model couples interfacial electrokinetics with shear-thinning rheology by considering a polymer depletion layer (PDL), which is a Newtonian fluid free of polymer due to the polymer-wall interactions, adjacent to each channel wall and a power-law fluid in the bulk. It predicts with good accuracy the experimental electroosmotic velocity in xanthan gum solutions with varying polymer and buffer concentrations across the tested electric fields. The only fitting parameter is PDL thickness, which decreases with the increasing polymer or buffer concentration but is independent of the electric field magnitude. The PDL to electricdouble-layer thickness ratio is found to play a critical role in understanding the electric field nonlinearity of the electroosmotic velocity.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"4 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-08DOI: 10.1021/acs.langmuir.5c03674
Ngoc Thuy Nguyen,Phat Tan Phan,Van Danh Truong,Thanh Xuan Le,DongQuy Hoang
Clean water scarcity represents a significant global challenge, driven by the degradation of surface water resources due to pollution and the impacts of climate change. Atmospheric water harvesting strategies using sorbents offer an available and sustainable solution. Most atmospheric water harvesting studies have focused on hydrogel designs utilizing conventional polymer desiccants derived from fossil fuels. These synthetic polymers are unsustainable and nonbiodegradable, causing negative ecological and public health impacts during degradation, which raises concerns about the direction of eco-friendly material science and technology. Here, biohydrogels (SCG0, SCG3, SCG5, and SCG7) based on chitosan and carboxymethyl cellulose from biomass were synthesized through a simple process. The effect of the cross-linking content on the properties of hydrogels and their water sorption performance were studied through FTIR, TGA, and FESEM analyses, mechanical strength, and water sorption experiments. A SCG5 hydrogel containing 5% w/w glutaraldehyde exhibits the most effective cross-linking formation, leading to superior thermal stability, good compressive strength, and a better water absorption performance compared to the SCG0, SCG3, and SCG7 hydrogels. The SCG5 hydrogel showed strong hydrophilicity when a drop wetted in its surface within 0.26 s. The mass change of SCG5 in water gained 2158% with a maximum sorption rate of 84.7 g g-1 h-1, and the water vapor sorption capacity of SCG5 at 90% RH reached 28.03% with a maximum sorption rate of 0.55 g g-1 h-1. Additionally, it exhibited rapid vapor desorption with a rate of 0.39 g g-1 h-1, releasing over 98% of the absorbed water within 20 min, and remarkable stability after multiple sorption-desorption cycles. Studies on different sorption kinetic models of biohydrogels based on chitosan and carboxymethyl cellulose were carried out, and the experimental data best fitted the Elovich model the most. It means that activated site sorption is the rate-limiting process; the sorption mechanism occurs on a nonuniform surface of biohydrogels or nonconstant active sites.
由于污染和气候变化的影响导致地表水资源退化，清洁水短缺是一项重大的全球挑战。使用吸附剂的大气水收集策略提供了一个可用的和可持续的解决方案。大多数大气集水研究都集中在利用来自化石燃料的传统聚合物干燥剂的水凝胶设计上。这些合成聚合物具有不可持续性和不可生物降解性，在降解过程中会对生态和公共健康造成负面影响，这引起了人们对环保材料科学与技术方向的关注。本文以生物质为原料，通过简单的工艺合成了壳聚糖和羧甲基纤维素为基础的生物水凝胶（SCG0、SCG3、SCG5和SCG7）。通过红外光谱（FTIR）、热重分析（TGA）、扫描电镜（FESEM）、力学强度和吸水实验研究了交联含量对水凝胶性能和吸水性能的影响。与SCG0、SCG3和SCG7水凝胶相比，含有5%戊二醛的SCG5水凝胶表现出最有效的交联形成，具有优越的热稳定性、良好的抗压强度和更好的吸水性能。SCG5水凝胶在0.26 s内液滴湿润表面，表现出较强的亲水性。SCG5在水中的质量变化达到2158%，最大吸附速率为84.7 g g-1 h-1；在90% RH条件下，SCG5的水蒸气吸附量达到28.03%，最大吸附速率为0.55 g g-1 h-1。水蒸气解吸速率为0.39 g g-1 h-1，在20 min内释放98%以上的水分，多次吸脱吸循环后稳定性良好。研究了壳聚糖和羧甲基纤维素生物水凝胶的不同吸附动力学模型，实验数据最符合Elovich模型。这意味着活化位点的吸附是一个限速过程；吸附机制发生在生物水凝胶的非均匀表面或非恒定活性位点上。
{"title":"Sustainable Atmospheric Water Harvesting Using Biomass-Derived Hydrogels: Effects of Cross-Linker Concentration and Sorption Kinetics.","authors":"Ngoc Thuy Nguyen,Phat Tan Phan,Van Danh Truong,Thanh Xuan Le,DongQuy Hoang","doi":"10.1021/acs.langmuir.5c03674","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c03674","url":null,"abstract":"Clean water scarcity represents a significant global challenge, driven by the degradation of surface water resources due to pollution and the impacts of climate change. Atmospheric water harvesting strategies using sorbents offer an available and sustainable solution. Most atmospheric water harvesting studies have focused on hydrogel designs utilizing conventional polymer desiccants derived from fossil fuels. These synthetic polymers are unsustainable and nonbiodegradable, causing negative ecological and public health impacts during degradation, which raises concerns about the direction of eco-friendly material science and technology. Here, biohydrogels (SCG0, SCG3, SCG5, and SCG7) based on chitosan and carboxymethyl cellulose from biomass were synthesized through a simple process. The effect of the cross-linking content on the properties of hydrogels and their water sorption performance were studied through FTIR, TGA, and FESEM analyses, mechanical strength, and water sorption experiments. A SCG5 hydrogel containing 5% w/w glutaraldehyde exhibits the most effective cross-linking formation, leading to superior thermal stability, good compressive strength, and a better water absorption performance compared to the SCG0, SCG3, and SCG7 hydrogels. The SCG5 hydrogel showed strong hydrophilicity when a drop wetted in its surface within 0.26 s. The mass change of SCG5 in water gained 2158% with a maximum sorption rate of 84.7 g g-1 h-1, and the water vapor sorption capacity of SCG5 at 90% RH reached 28.03% with a maximum sorption rate of 0.55 g g-1 h-1. Additionally, it exhibited rapid vapor desorption with a rate of 0.39 g g-1 h-1, releasing over 98% of the absorbed water within 20 min, and remarkable stability after multiple sorption-desorption cycles. Studies on different sorption kinetic models of biohydrogels based on chitosan and carboxymethyl cellulose were carried out, and the experimental data best fitted the Elovich model the most. It means that activated site sorption is the rate-limiting process; the sorption mechanism occurs on a nonuniform surface of biohydrogels or nonconstant active sites.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"2 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen-bonded organic systems (HBOS) combine facile synthesis, solution processability, regenerability, and water stability, making them attractive for the design of functional materials. Motivated by the limited report on chiral HBOS, we explored the hydrothermal assembly of melamine (M) and l-glutamic acid (L-GA) and unexpectedly yielded a crystalline 2D melamine-cyanuric acid (M-CA) adduct. In this transformation, L-GA served both as an acid catalyst promoting partial in situ hydrolysis of M to cyanuric acid (CA), and as a structure-directing agent, facilitating the M-CA self-assembly. Nanoindentation revealed that M-CA exhibits significantly higher penetration depths than those of M and CA, consistent with its layered packing and presence of hollow hexagonal channels. In contrast, M displayed the highest elastic modulus and hardness due to its rigid herringbone packing. Energy framework analysis linked the nanomechanical behavior of the crystals to the differences in hydrogen-bonding strength and topology. Functionally, M-CA demonstrated superior guest adsorption (rhodamine B 96.75 mg g-1 and methyl orange 102.50 mg g-1) with excellent recyclability over multiple cycles, outperforming both M and CA by ∼4-fold. These results establish a correlation between the structure of HBOS, nanomechanical properties, and adsorption performance, offering insights into the design of hydrogen-bonded functional materials.
{"title":"Correlating Nanomechanical Behavior and Adsorption Performance in a Serendipitously Assembled Two-Dimensional Hydrogen-Bonded Organic System.","authors":"Ashis Chhetri,Shamim Ahmad,Sumana Podder,Srinu Tothadi,Subashani Maniam,Chilla Malla Reddy,Joyee Mitra","doi":"10.1021/acs.langmuir.5c04711","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c04711","url":null,"abstract":"Hydrogen-bonded organic systems (HBOS) combine facile synthesis, solution processability, regenerability, and water stability, making them attractive for the design of functional materials. Motivated by the limited report on chiral HBOS, we explored the hydrothermal assembly of melamine (M) and l-glutamic acid (L-GA) and unexpectedly yielded a crystalline 2D melamine-cyanuric acid (M-CA) adduct. In this transformation, L-GA served both as an acid catalyst promoting partial in situ hydrolysis of M to cyanuric acid (CA), and as a structure-directing agent, facilitating the M-CA self-assembly. Nanoindentation revealed that M-CA exhibits significantly higher penetration depths than those of M and CA, consistent with its layered packing and presence of hollow hexagonal channels. In contrast, M displayed the highest elastic modulus and hardness due to its rigid herringbone packing. Energy framework analysis linked the nanomechanical behavior of the crystals to the differences in hydrogen-bonding strength and topology. Functionally, M-CA demonstrated superior guest adsorption (rhodamine B 96.75 mg g-1 and methyl orange 102.50 mg g-1) with excellent recyclability over multiple cycles, outperforming both M and CA by ∼4-fold. These results establish a correlation between the structure of HBOS, nanomechanical properties, and adsorption performance, offering insights into the design of hydrogen-bonded functional materials.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"20 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adsorption is a simple yet effective technique for the removal of emerging contaminants. In this study, pure graphitic carbon nitride (g-C3N4) and nickel-doped g-C3N4 (Ni-g-C3N4) were synthesized via a thermal polycondensation method and evaluated as adsorbents for doxycycline removal. Structural and morphological characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The results confirmed the successful incorporation of Ni2+ into the g-C3N4 matrix, with homogeneous Ni2+ distribution and no secondary phases. Morphological analysis indicated that nickel doping induced only slight changes in the g-C3N4 morphology. Adsorption experiments revealed that both materials exhibited enhanced adsorption capacity at pH 9, with Ni-g-C3N4 achieving a significantly higher removal efficiency (53.4%) compared to g-C3N4 (14.2%). This improvement was attributed to Ni2+-induced positively charged regions, facilitating stronger adsorbate-adsorbent interactions. Kinetic analysis demonstrated that doxycycline adsorption onto Ni-g-C3N4 followed a pseudo-second-order model. Among the tested isotherm models, the Sips model provided the best fit, yielding maximum adsorption capacities of 37.889 mg·g-1 for g-C3N4 and 116.265 mg·g-1 for Ni-g-C3N4. Theoretical calculations corroborated experimental findings, confirming that Ni2+ incorporation in the g-C3N4 structure enhances adsorption capacity by facilitating strong chemical bonds between doxycycline and the Ni-g-C3N4 adsorbent surface.
{"title":"Graphitic Carbon Nitride and Nickel-Doped Graphitic Carbon Nitride for Doxycycline Removal: Adsorption Efficiency and Mechanistic Insights.","authors":"Daniela Cristina Feitosa Angelo,Raíssa Santos Sousa,Rafael Meuredi Pinheiro Souza,Douglas Henrique Pereira,Gleice Botelho","doi":"10.1021/acs.langmuir.5c03760","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c03760","url":null,"abstract":"Adsorption is a simple yet effective technique for the removal of emerging contaminants. In this study, pure graphitic carbon nitride (g-C3N4) and nickel-doped g-C3N4 (Ni-g-C3N4) were synthesized via a thermal polycondensation method and evaluated as adsorbents for doxycycline removal. Structural and morphological characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The results confirmed the successful incorporation of Ni2+ into the g-C3N4 matrix, with homogeneous Ni2+ distribution and no secondary phases. Morphological analysis indicated that nickel doping induced only slight changes in the g-C3N4 morphology. Adsorption experiments revealed that both materials exhibited enhanced adsorption capacity at pH 9, with Ni-g-C3N4 achieving a significantly higher removal efficiency (53.4%) compared to g-C3N4 (14.2%). This improvement was attributed to Ni2+-induced positively charged regions, facilitating stronger adsorbate-adsorbent interactions. Kinetic analysis demonstrated that doxycycline adsorption onto Ni-g-C3N4 followed a pseudo-second-order model. Among the tested isotherm models, the Sips model provided the best fit, yielding maximum adsorption capacities of 37.889 mg·g-1 for g-C3N4 and 116.265 mg·g-1 for Ni-g-C3N4. Theoretical calculations corroborated experimental findings, confirming that Ni2+ incorporation in the g-C3N4 structure enhances adsorption capacity by facilitating strong chemical bonds between doxycycline and the Ni-g-C3N4 adsorbent surface.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"55 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145696851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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