1
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Ouyang J, Zhang M, Xiong W, Zhou L, Zhao L, Li Z, Zhou C, Chen H, Luo Y, Fang S, Baughman RH. High performance supercapacitors deploying cube-templated tracheid cavities of wood-derived carbon. J Colloid Interface Sci 2024; 671:145-153. [PMID: 38795535 DOI: 10.1016/j.jcis.2024.05.172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 05/21/2024] [Accepted: 05/22/2024] [Indexed: 05/28/2024]
Abstract
Wood-derived carbon, with its strong tracheid array structure, is an ideal material for use as a self-supporting electrode in supercapacitors. By leveraging the inherent through pore structure and surface affinity found in wood tracheids, we successfully engineered a highly spatially efficient cube-templated porous carbon framework inside carbonized wood tracheid cavities through precise control over precursor crystallization temperatures. This innovative cubic channel architecture effectively maximizes up to (79 ± 1)% of the cavity volume in wood-derived carbon while demonstrating exceptional hydrophilicity and high conductivity properties, facilitating the development of supercapacitors with enhanced areal/volumetric capacitances (2.65F cm-2/53.0F cm-3 at 5.0 mA cm-2) as well as superior areal/volumetric energy densities (0.37 mWh cm-2/7.36 mWh cm-3 at 2.5 mW cm-2). The fabrication of these cube-templated channels with high cube filling content is not only simple and precisely controllable, but also environmentally friendly. The proposed method eliminates the conventional acid-base treatment process for pore formation, facilitating the rapid development and practical implementation of thick electrodes with superior performance in supercapacitors. Moreover, it offers a universal research approach for the commercialization of wood-derived thick electrodes.
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Affiliation(s)
- Jie Ouyang
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Mengmeng Zhang
- The Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Wanning Xiong
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Liangliang Zhou
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Linlin Zhao
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Zejun Li
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Cui Zhou
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Hong Chen
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China
| | - Yongfeng Luo
- Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, College of Science, Material Science and Engineering School, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China.
| | - Shaoli Fang
- The Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Ray H Baughman
- The Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080, USA.
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2
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Xu X, Stellacci F. Amino Acids and Their Biological Derivatives Modulate Protein-Protein Interactions in an Additive Way. J Phys Chem Lett 2024; 15:7154-7160. [PMID: 38967372 PMCID: PMC11261602 DOI: 10.1021/acs.jpclett.4c01175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/21/2024] [Accepted: 07/02/2024] [Indexed: 07/06/2024]
Abstract
Protein-protein interactions (PPIs) differ when measured in test tubes and cells due to the complexity of the intracellular environment. Free amino acids (AAs) and their derivatives constitute a significant fraction of the intracellular volume and mass. Recently, we have found that AAs have a generic property of rendering protein dispersions more stable by reducing the net attractive part of PPIs. Here, we study the effects on PPIs of different AA derivatives, AA mixtures, and short peptides. We find that all the tested AA derivatives modulate PPIs in solution as effectively as AAs. Furthermore, we show that the modulation effect is additive when AAs form mixtures or are bound into short peptides. Therefore, this study demonstrates the additive effects of a class of small molecules (i.e., AAs and their biological derivatives) on PPIs and provides insights into rationally designing biocompatible molecules for stabilizing protein interactions and consequently tuning protein functions.
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Affiliation(s)
- Xufeng Xu
- Institute
of Materials, Ecole Polytechnique Fédérale
de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Francesco Stellacci
- Institute
of Materials, Ecole Polytechnique Fédérale
de Lausanne (EPFL), Lausanne 1015, Switzerland
- Bioengineering
Institute, Ecole Polytechnique Fédérale
de Lausanne (EPFL), Lausanne 1015, Switzerland
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3
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Tsuchiya H, Nakamura N, Ohta S. Centrifugal Field-Flow Fractionation Enables Detection of Slight Aggregation of Nanoparticles That Impacts Their Biomedical Applications. Anal Chem 2024; 96:5976-5984. [PMID: 38587278 DOI: 10.1021/acs.analchem.4c00240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Nanoparticles (NPs) are anticipated to be used for various biomedical applications in which their aggregation has been an important issue. However, concerns regarding slightly aggregated but apparently monodispersed NPs have been difficult to address because of a lack of appropriate evaluation methods. Here, we report centrifugal field-flow fractionation (CF3) as a powerful method for analyzing the slight aggregation of NPs, using antibody-modified gold NPs (Ab-AuNPs) prepared by a conventional protocol with centrifugal purification as a model. While common evaluation methods such as dynamic light scattering cannot detect significant signs of aggregation, CF3 successfully detects distinct peaks of slightly aggregated NPs, including dimers and trimers. Their impact on biological interactions was also demonstrated by a cellular uptake study: slightly aggregated Ab-AuNPs exhibited 1.8 times higher cellular uptake than monodispersed Ab-AuNPs. These results suggest the importance of aggregate evaluation via CF3 as well as the need for careful attention to the bioconjugation procedures for NPs.
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Affiliation(s)
- Hiroki Tsuchiya
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Noriko Nakamura
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Bioengineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Seiichi Ohta
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Bioengineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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4
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Wang H, Xu X, Polla RL, Silva PJ, Ong QK, Stellacci F. Ligand concentration determines antiviral efficacy of silica multivalent nanoparticles. J Colloid Interface Sci 2024; 657:327-333. [PMID: 38043234 DOI: 10.1016/j.jcis.2023.11.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/14/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023]
Abstract
We have learned from the recent COVID-19 pandemic that the emergence of a new virus can quickly become a global health burden and kill millions of lives. Antiviral drugs are essential in our fight against viral diseases, but most of them are virus-specific and are prone to viral mutations. We have developed broad-spectrum antivirals based on multivalent nanoparticles grafted with ligands that mimic the target of viral attachment ligands (VALs). We have shown that when the ligand has a sufficiently long hydrophobic tail, the inhibition mechanism switches from reversible (virustatic) to irreversible (virucidal). Here, we investigate further how ligand density and particle size affect antiviral efficacy, both in terms of half-inhibitory concentration (IC50) and of reversible vs irreversible mechanism. We designed antiviral silica nanoparticles modified with 11-mercaptoundecane-1-sulfonic acid (MUS), a ligand that mimics heparan sulfate proteoglycans (HSPG) and we showed that these nanoparticles can be synthesized with different sizes (4-200 nm) and ligand grafting densities (0.59-10.70 /nm2). By testing these particles against herpes simplex virus type 2 (HSV-2), we show that within the size and density ranges studied, the antiviral IC50 is determined solely by equivalent ligand concentration. The nanoparticles are found to be virucidal at all sizes and densities studied.
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Affiliation(s)
- Heyun Wang
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland
| | - Xufeng Xu
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland
| | - Rémi La Polla
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland
| | - Paulo Jacob Silva
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland
| | - Quy Khac Ong
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland
| | - Francesco Stellacci
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland; Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland; Global Health Institute, École Polytechnique Fédérale de Lausanne (EPFL), Station 12, CH-1015 Lausanne, Switzerland.
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5
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Kunnas P, Moradi MA, Sommerdijk N, de Jonge N. Strategy for optimizing experimental settings for studying low atomic number colloidal assemblies using liquid phase scanning transmission electron microscopy. Ultramicroscopy 2022; 240:113596. [PMID: 35908325 DOI: 10.1016/j.ultramic.2022.113596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 07/08/2022] [Accepted: 07/21/2022] [Indexed: 10/16/2022]
Abstract
Observing processes of nanoscale materials of low atomic number is possible using liquid phase electron microscopy (LP-EM). However, the achievable spatial resolution (d) is limited by radiation damage. Here, we examine a strategy for optimizing LP-EM experiments based on an analytical model and experimental measurements, and develop a method for quantifying image quality at ultra low electron dose De using scanning transmission electron microscopy (STEM). As experimental test case we study the formation of a colloidal binary system containing 30 nm diameter SiO2 nanoparticles (SiONPs), and 100 nm diameter polystyrene microspheres (PMs). We show that annular dark field (DF) STEM is preferred over bright field (BF) STEM for practical reasons. Precise knowledge of the material's density is crucial for the calculations in order to match experimental data. To calculate the detectability of nano-objects in an image, the Rose criterion for single pixels is expanded to a model of the signal to noise ratio obtained for multiple pixels spanning the image of an object. Using optimized settings, it is possible to visualize the radiation-sensitive, hierarchical low-Z binary structures, and identify both components.
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Affiliation(s)
- Peter Kunnas
- INM- Leibniz Institute for New Materials, Saarbrücken 66123, Germany; Faculty of Physics, Quantum Imaging and Biophysics, University of Vienna, Vienna 1090, Austria
| | - Mohammad-Amin Moradi
- Department of Chemical Engineering and Chemistry, Laboratory of Physical Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB, the Netherlands
| | - Nico Sommerdijk
- Department of Biochemistry, Radboud University Medical Center, Nijmegen 6525 GA, the Netherlands
| | - Niels de Jonge
- INM- Leibniz Institute for New Materials, Saarbrücken 66123, Germany; Department of Physics, Saarland University, Saarbrücken 66123, Germany.
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6
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Concentration Quantification of TiO 2 Nanoparticles Synthesized by Laser Ablation of a Ti Target in Water. MATERIALS 2022; 15:ma15093146. [PMID: 35591479 PMCID: PMC9104483 DOI: 10.3390/ma15093146] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 12/20/2022]
Abstract
In this work, we present a quantitative method for determining the concentration of metal oxide nanoparticles (NP) synthesized by laser ablation in liquid. The case study was performed with titanium dioxide nanoparticles (TiO2 NP), which were synthesized by laser ablation of a Ti target in water. After synthesis, a colloidal solution was analyzed with UV-Vis spectroscopy. At the same time, the craters that remained on the Ti target after ablation were evaluated with an optical microscope to determine the volume of the ablated material. SEM microscopy was used to determine the TiO2 NP size distribution. It was found that synthesized TiO2 NP followed a Log-Normal diameter distribution with a maximum at about 64 nm. From the volume of ablated material and NP size distribution, under the assumption that most of the ablated material is consumed to form nanoparticles, a concentration of nanoparticles can be determined. The proposed method is verified by comparing the calculated concentrations to the values obtained from the Beer–Lambert law using the Mie scattering theory for the NP cross-section calculation.
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7
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Xu X, de With G, Cölfen H. Self-association and gel formation during sedimentation of like-charged colloids. MATERIALS HORIZONS 2022; 9:1216-1221. [PMID: 35113101 DOI: 10.1039/d1mh01854j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Formation of superstructures from colloidal dispersion involves a continuous increase in particle concentration, resulting in increasingly more complicated interparticle interaction. At high particle concentration, the presence of the super-crowding effect, strong non-ideality in addition to significant light absorption and scattering makes particle analysis very difficult. Here we report quantitative molecular, microscopic and macroscopic experimental results on like-charged colloids with concentration up to 60 vol%, close to the densest possible packing of spheres. It is achieved by conducting sedimentation-diffusion-equilibrium analytical ultracentrifugation (SE-AUC) on a concentrated dispersion of colloidal silica nanoparticles in a refractive-index-matching solvent. Surprisingly, we observed the self-association and even colloidal gel formation of like-charged colloids at very high concentration. Further experiments indicate that the attraction force may be counter-ion mediated. These results represent an important step forward in understanding complicated interparticle interaction in extremely high concentration, which is vital for the controlled fabrication of colloidal superstructures.
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Affiliation(s)
- Xufeng Xu
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld 14, PO Box 513, 5600MB, Eindhoven, The Netherlands.
| | - Gijsbertus de With
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld 14, PO Box 513, 5600MB, Eindhoven, The Netherlands.
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstrasse 10, Box 714, 78457, Konstanz, Germany.
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8
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Zhang Z, Yi G, Li P, Zhang X, Wan Z, Wang X, Zhang C, Zhang Y. Recent Advances in Binary Colloidal Crystals for Photonics and Porous Material Fabrication. J Phys Chem B 2021; 125:6012-6022. [PMID: 34038121 DOI: 10.1021/acs.jpcb.1c03349] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the past few years, binary colloidal crystals (BCCs) composed of both large and small particles have attracted considerable attention from the scientific community as an exciting alternative to single colloidal crystals (SCCs). In particular, more complex structures with diverse nanotopographies and desirable optical properties of BCCs can be obtained by various colloidal assembly methods, as compared to SCCs. Furthermore, high accuracy in crystal growth with controllable stoichiometries allows for a great deal of promising applications in the fields of both interfacial and material sciences. The visible-light diffraction property of BCCs is more superior than that of SCCs, which makes them have more promising applications in the fabrication of photonic crystals with full band gaps. On the other hand, their spherical shapes and ease of removal property make them ideal templates for ordered porous material fabrication. Hence, this perspective outlined recent advances in assembly approaches of BCCs, with an emphasis on their promising applications for advanced photonics and multifunctional porous material fabrication. Eventually, some challenging yet important issues and some future perspectives are further discussed.
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Affiliation(s)
- Zhengting Zhang
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Guiyun Yi
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Peng Li
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Xiuxiu Zhang
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Zhuoyan Wan
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Xiaodong Wang
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Chuanxiang Zhang
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
| | - Yulong Zhang
- College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, China.,State Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization, Jiaozuo 454003, China.,Henan Key Laboratory of Coal Green Conversion, Jiaozuo 454003, China
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9
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Xu X, Cölfen H. Ultracentrifugation Techniques for the Ordering of Nanoparticles. NANOMATERIALS 2021; 11:nano11020333. [PMID: 33513966 PMCID: PMC7912273 DOI: 10.3390/nano11020333] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/22/2021] [Accepted: 01/22/2021] [Indexed: 01/07/2023]
Abstract
A centrifugal field can provide an external force for the ordering of nanoparticles. Especially with the knowledge from in-situ characterization by analytical (ultra)centrifugation, nanoparticle ordering can be rationally realized in preparative (ultra)centrifugation. This review summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. This review is divided into three main parts. In the introduction part, the history of ordering microbeads in gravity is discussed and with the size of particles reduced to nanometers, a centrifugal field is necessary. In the next part, the research on the ordering of nanoparticles in analytical and preparative centrifugation in recent decades is described. In the last part, the applications of the functional materials, fabricated from centrifugation-induced nanoparticle superstructures are briefly discussed.
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Affiliation(s)
- Xufeng Xu
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612AE Eindhoven, The Netherlands;
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, Box 714, 78457 Konstanz, Germany
- Correspondence:
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10
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Xu X, Biesheuvel PM, Cölfen H, Spruijt E. Layering of bidisperse charged nanoparticles in sedimentation. SOFT MATTER 2020; 16:4718-4722. [PMID: 32400820 DOI: 10.1039/d0sm00588f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Bidisperse mixtures of charged nanoparticles form separate layers upon centrifugation as a result of minimization of the system's free energy in sedimentation-diffusion equilibrium. Different factors were investigated experimentally for their effects on the layering, and are supported by theoretical calculations of the full sedimentation profiles. Surprisingly, lighter/smaller nanoparticles can even sink below heavier/larger ones when the particle surface charge is carefully tuned. This study provides deeper insights into the control of layering in polydisperse particle mixtures during sedimentation.
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Affiliation(s)
- Xufeng Xu
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612 AE Eindhoven, The Netherlands.
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11
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Spinnrock A, Cölfen H. Putting a New Spin on It: Gradient Centrifugation for Analytical and Preparative Applications. Chemistry 2019; 25:10026-10032. [PMID: 30980567 DOI: 10.1002/chem.201900974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Indexed: 11/07/2022]
Abstract
Gradient centrifugation is an important technique in chemistry, biology, materials science and engineering. It has big potential beyond the well-known centrifugation for separation of molecules and particles. Various possibilities for special analysis and separation of particles, but also preparative applications like the production of gradient materials and controlled polymerizations exist. In all examples, a gradient of physical and/or chemical properties is generated by centrifugation and used for the further application. In this Concept article, selected examples of gradient centrifugation are presented, to show important developments in the field and discuss their applications, potential, and limitations. It concludes by analysing future trends of gradient centrifugation that are relevant for academic and industrial usage.
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Affiliation(s)
- Andreas Spinnrock
- Physical Chemistry, University of Konstanz, Universitätsstrasse 10, Box 714, 78457, Konstanz, Germany
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstrasse 10, Box 714, 78457, Konstanz, Germany
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12
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Xu X, Cölfen H. Binary Colloidal Nanoparticles with a Large Size Ratio in Analytical Ultracentrifugation. Chemphyschem 2019; 20:1799-1803. [PMID: 31125481 DOI: 10.1002/cphc.201900299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/27/2019] [Indexed: 11/11/2022]
Abstract
Sedimenting colloidal particles may feel a surprisingly strong buoyancy in a mixture with other particles of a considerably larger size. In this paper we investigated the buoyancy of colloidal particles in a concentrated binary suspension in situ in a centrifugal field. After dispersing two different fluorescence-labeled silica nanoparticles with a large size ratio (90 nm and 30 nm, size ratio: 3) in a refractive index matching solvent, we used a multi-wavelength analytical ultracentrifuge to measure the concentration gradients of both particles in situ. The concentration of the 90 nm silica nanoparticles was used to calculate the effective solvent density for the 30 nm silica nanoparticles. The exponential Boltzmann equation for the sedimentation-diffusion equilibrium with locally varying effective solvent density was then used to theoretically predict the concentration gradient of 30 nm silica nanoparticles, which describes the experimental results very well. This finding proves the validity of effective buoyancy in colloidal mixtures and provides a good model to study sedimenting polydisperse colloids.
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Affiliation(s)
- Xufeng Xu
- Physical Chemistry, University of Konstanz, Universitätsstr 10, Box 714, 78457, Konstanz, Germany.,Department of Chemical Engineering and Chemistry, Eindhoven University of Technology 5600 MB Eindhoven, Netherlands
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstr 10, Box 714, 78457, Konstanz, Germany
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13
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Controlled Preparation of Nanoparticle Gradient Materials by Diffusion. NANOMATERIALS 2019; 9:nano9070988. [PMID: 31323928 PMCID: PMC6669869 DOI: 10.3390/nano9070988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/04/2019] [Accepted: 07/04/2019] [Indexed: 12/12/2022]
Abstract
Nanoparticle gradient materials combine a concentration gradient of nanoparticles with a macroscopic matrix. This way, specific properties of nanoscale matter can be transferred to bulk materials. These materials have great potential for applications in optics, electronics, and sensors. However, it is challenging to monitor the formation of such gradient materials and prepare them in a controlled manner. In this study, we present a novel universal approach for the preparation of this material class using diffusion in an analytical ultracentrifuge. The nanoparticles diffuse into a molten thermoreversible polymer gel and the process is observed in real-time by measuring the particle concentrations along the length of the material to establish a systematic understanding of the gradient generation process. We extract the apparent diffusion coefficients using Fick’s second law of diffusion and simulate the diffusion behavior of the particles. When the desired concentration gradient is achieved the polymer solution is cooled down to fix the concentration gradient in the formed gel phase and obtain a nanoparticle gradient material with the desired property gradient. Gradients of semiconductor nanoparticles with different sizes, fluorescent silica particles, and spherical superparamagnetic iron oxide nanoparticles are presented. This method can be used to produce tailored nanoparticle gradient materials with a broad range of physical properties in a simple and predictable way.
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