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Jie H, Feng K, Lu M, Jin Z. Modulation of Tannic Acid on the Cholesteric Structure of Cellulose Nanocrystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13834-13843. [PMID: 38920318 DOI: 10.1021/acs.langmuir.4c00767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
The chiral nematic phase structure, formed by the self-assembly of cellulose nanocrystals (CNCs) in an aqueous suspension and maintained in a solid film, shows great potential for optical applications. To achieve complex structures in optical devices, it is crucial to subject CNCs to specific shearing processes, such as spinning and printing. Understanding the structural and property changes of the CNC liquid crystal phase in these processes is of utmost importance. In this study, we investigated the effect of adding tannic acid (TA) on the rheological properties and cholesteric phase structures of CNCs/TA mixed suspensions. By calculating the surface site interaction points, we observed that TA can adsorb onto the surface of CNC rods in suspensions through hydrogen bonding. Through characterization techniques, such as polarized optical microscopy, rheology, and synchrotron SAXS, we examined the effects of TA addition on the microstructure and rheological properties of the CNC liquid crystal phase and clarified the change relating to the system composition. Under the same CNC concentration, the volume fraction of the anisotropic phase, the pitch, and the rod spacing of the cholesteric phase were not significantly affected by the addition of TA. However, the system viscosity was significantly reduced with the appropriate amount of TA (2 wt %), in a wide range of CNC concentrations (up to 15 wt % CNCs). The flow indexes (n) in Region I and Region III of steady-state shear curves of CNCs/TA systems (11-15 wt % CNCs) were compared. Moreover, we introduced the well-established theoretical models for liquid crystal polymers to tentatively interpret Region I of the CNCs/TA cholesteric phase and realized that increased numbers of smaller cholesteric-phase domains in the CNCs/TA system and interfacial modification by TA may contribute to the fluidity change. The feature of the domain texture of CNCs/TA systems is verified by polarized optical microscopy observations.
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Affiliation(s)
- Hui Jie
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Kai Feng
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Mengfan Lu
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Zhaoxia Jin
- Department of Chemistry, Renmin University of China, Beijing 100872, China
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Xu Y, Gilbert EP, Sokolova A, Stokes JR. Phase transition and gelation in cellulose nanocrystal-based aqueous suspensions studied by SANS. J Colloid Interface Sci 2024; 658:660-670. [PMID: 38134674 DOI: 10.1016/j.jcis.2023.12.041] [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: 10/08/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023]
Abstract
HYPOTHESIS Aqueous suspensions of cellulose nanocrystals (CNC) form a re-entrant liquid crystal (LC) phase with increasing salinity. Phase separation occurs in this LC state leading to a biphasic gel with a flow programmable structure that can be used to form anisotropic soft materials. We term this state a Liquid Crystal Hydroglass (LCH). Defining the mechanisms by which the LCH forms requires detailed structural analysis at the mesoscopic length scale. EXPERIMENTS By utilising Small Angle Neutron Scattering (SANS), we investigated the microstructure transitions in CNC suspensions, with a particular focus on the unique LC re-entrancy and gelation into the biphasic LCH. FINDINGS Scattering from LCH gels comprises contributions from a dispersed liquid state and static heterogeneity, characterised using a Lorentzian-Gaussian model of inhomogeneity. This conceptually supports a gelation mechanism (spinodal decomposition) in CNC suspensions towards a biphasic structure of the LCH. It also demonstrates that, with increasing salinity, the non-monotonic variation in effective volume fraction of CNC rods fundamentally causes the LC re-entrancy. This work provides the first experimental characterisation of the LC-re-entrancy and formation of an anisotropic LCH gel. The proposed mechanism can be extended to understanding the general behaviour of anisotropic colloids.
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Affiliation(s)
- Yuan Xu
- School of Chemical Engineering, The University of Queensland, Queensland, 4072, Australia.
| | - Elliot P Gilbert
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales, 2234, Australia
| | - Anna Sokolova
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales, 2234, Australia
| | - Jason R Stokes
- School of Chemical Engineering, The University of Queensland, Queensland, 4072, Australia.
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3
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Speets PNA, Kalkman J. Experiment and theory of the complex refractive index of dense colloidal media. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2024; 41:214-228. [PMID: 38437334 DOI: 10.1364/josaa.510603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/15/2023] [Indexed: 03/06/2024]
Abstract
The complex refractive index is analyzed by measuring its scattering attenuation μ s, group index n g, and group velocity dispersion (GVD) for 100 nm diameter silica nanoparticles dispersed in water. The experiments were performed for wavelengths between 410 nm and 930 nm. The experimental results were compared with different mixing models for the complex refractive index of colloidal suspensions. The group index linearly scaled with the volume fraction both in experiment and for all tested models. It was found that the GVD has a nonlinear dependence on volume fraction in agreement with the coupled dipole model of Parola et al. [J. Chem. Phys.141, 124902 (2014)JCPSA60021-960610.1063/1.4895961] The scattering attenuation is in good agreement with both the coupled dipole model and the low frequency quasi-crystalline approximation [J. Electromagn. Waves Appl.2, 757 (1988)JEWAE50920-507110.1163/156939388X00053] that take particle correlations into account. With an iterative fitting procedure of all the data based on both the coupled dipole model and the quasi-crystalline approximation, the refractive index, porosity, and size of the nanoparticles were determined. We determined that the coupled dipole model is in best agreement with the data.
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Kim S, Hwang C, Jeong DI, Park J, Kim H, Lee K, Lee J, Lee S, Cho H. Nanorod/nanodisk-integrated liquid crystalline systems for starvation, chemodynamic, and photothermal therapy of cancer. Bioeng Transl Med 2023; 8:e10470. [PMID: 37693066 PMCID: PMC10487320 DOI: 10.1002/btm2.10470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/20/2022] [Accepted: 11/30/2022] [Indexed: 09/12/2023] Open
Abstract
Indocyanine green (ICG), glucose oxidase (GOx), and copper(II) sulfate (Cu)-installed hybrid gel based on organic nanorod (cellulose nanocrystal [CNC]) and inorganic nanodisk (Laponite [LAP]) was developed to perform a combination of starvation therapy (ST), chemodynamic therapy (CDT), and photothermal therapy (PTT) for localized cancers. A hybrid CNC/LAP network with a nematic phase was designed to enable instant gelation, controlled viscoelasticity, syringe injectability, and longer in vivo retention. Moreover, ICG was introduced into the CNC/LAP gel system to induce hyperthermia of tumor tissue, amplifying the CDT effect; GOx was used for glucose deprivation (related to the Warburg effect); and Cu was introduced for hydroxyl radical generation (based on Fenton-like chemistry) and cellular glutathione (GSH) degradation in cancer cells. The ICG/GOx/Cu-installed CNC/LAP gel in combination with near-infrared (NIR) laser realized improved antiproliferation, cellular reactive oxygen species (ROS) generation, cellular GSH degradation, and apoptosis induction in colorectal cancer (CT-26) cells. In addition, local injection of the CNC/ICG/GOx/Cu/LAP gel into the implanted CT-26 tumor while irradiating it with NIR laser provided strong tumor growth suppression effects. In conclusion, the designed hybrid nanorod/nanodisk gel network can be efficiently applied to the local PTT/ST/CDT of cancer cells.
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Affiliation(s)
- Sungyun Kim
- Department of PharmacyCollege of Pharmacy, Kangwon National UniversityChuncheonGangwonRepublic of Korea
| | - ChaeRim Hwang
- Department of PharmacyCollege of Pharmacy, Kangwon National UniversityChuncheonGangwonRepublic of Korea
| | - Da In Jeong
- Department of PharmacyCollege of Pharmacy, Kangwon National UniversityChuncheonGangwonRepublic of Korea
| | - JiHye Park
- Department of PharmacyCollege of Pharmacy, Kangwon National UniversityChuncheonGangwonRepublic of Korea
| | - Han‐Jun Kim
- Terasaki Institute for Biomedical InnovationLos AngelesCaliforniaUSA
- College of PharmacyKorea UniversitySejongSouth Korea
| | - KangJu Lee
- School of Healthcare and Biomedical EngineeringChonnam National UniversityYeosuRepublic of Korea
| | - Junmin Lee
- Department of Materials Science and EngineeringPohang University of Science and Technology (POSTECH)PohangRepublic of Korea
| | - Seung‐Hwan Lee
- Institute of Forest ScienceKangwon National UniversityChuncheonRepublic of Korea
- Department of Forest Biomaterials EngineeringCollege of Forest and Environmental Sciences, Kangwon National UniversityChuncheonGangwonRepublic of Korea
| | - Hyun‐Jong Cho
- Department of PharmacyCollege of Pharmacy, Kangwon National UniversityChuncheonGangwonRepublic of Korea
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Antoniw JM, Hallman MT, Kiriakou MV, Morse T, Cranston ED. Colloidal Stability Window for Carboxylated Cellulose Nanocrystals: Considerations for Handling, Characterization, and Formulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:10321-10334. [PMID: 37459396 DOI: 10.1021/acs.langmuir.3c00319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
The scale of production of cellulose nanocrystals (CNCs) has increased dramatically to meet the growing demand for sustainably sourced materials. This work defines the colloidal stability window for commercially produced carboxylated CNCs (DextraCel) compared to the more traditional sulfated CNCs. Phase diagrams showing the stable, reversibly agglomerated, irreversibly aggregated/sedimented, and colloidal glass "zones" as a function of suspension pH, ionic strength, CNC surface charge content, counterion, and concentration are presented. The pKa of carboxylated CNCs was measured to be 5.1, and suspensions of carboxylated CNCs (0.5-1.5 wt %) were visually stable from pH 3 to 11 (without salt). Carboxylated CNCs were highly sensitive to ionic strength, demonstrating some agglomeration with as little as 5 mM NaCl, supporting that weak acid surface groups and lower charge contents make CNCs more sensitive to solution conditions. Surface charge content had the greatest influence on colloidal stability followed by the counterion; carboxylated CNCs were more stable in the "as-received" sodium form, whereas sulfated CNCs had improved stability in acid form after ion exchange. The stability of carboxylated CNCs with industrially relevant additives (ionic and nonionic surfactants and initiators) was also investigated. Less concentrated suspensions were more colloidally stable, emphasizing that characterization and processing of CNCs favor dilute conditions. If carboxylated CNCs are subjected to conditions outside of their colloidal stability window, simple dilution or pH adjustment does not return them to colloidally stable discrete nanoparticles; however, ultrasonication can redisperse agglomerates. This study offers guidelines for handling carboxylated CNCs to broaden the range of products that can be improved by their incorporation.
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Affiliation(s)
- Julia M Antoniw
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Madeleine T Hallman
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | | | | | - Emily D Cranston
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
- Department of Wood Science, University of British Columbia, Vancouver, British Columbia, CanadaV6T 1Z3
- UBC Bioproducts Institute, 2385 East Mall, Vancouver, British Columbia, Canada V6T 1Z4
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6
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Detert M, Santos TP, Shen AQ, Calabrese V. Alignment-Rheology Relationship of Biosourced Rod-Like Colloids and Polymers under Flow. Biomacromolecules 2023. [PMID: 37364888 DOI: 10.1021/acs.biomac.3c00347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Fluids composed of biosourced rod-like colloids (RC) and rod-like polymers (RP) have been extensively studied due to various promising applications relying on their flow-induced orientation (e.g., fiber spinning). However, the relationship between RC and RP alignment and the resulting rheological properties is unclear due to experimental challenges. We investigate the alignment-rheology relationship for a variety of biosourced RC and RP, including cellulose-based particles, filamentous viruses, and xanthan gum, by simultaneous measurements of the shear viscosity and fluid anisotropy under rheometric shear flows. For each system, the RC and RP contribution to the fluid viscosity, captured by the specific viscosity ηsp, follows a universal trend with the extent of the RC and RP alignment independent of concentration. We further exploit this unique rheological-structural link to retrieve a dimensionless parameter (β) directly proportional to ηsp at zero shear rate (η0,sp), a parameter often difficult to access from experimental rheometry for RC and RP with relatively long contour lengths. Our results highlight the unique link between the flow-induced structural and rheological changes occurring in RC and RP fluids. We envision that our findings will be relevant in building and testing microstructural constitutive models to predict the flow-induced structural and rheological evolution of fluids containing RC and RP.
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Affiliation(s)
- Marvin Detert
- Physics of Fluids, Max Planck Center Twente for Complex Fluid Dynamics, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
- Physics of Interfaces and Nanomaterials, MESA+ Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | | | - Amy Q Shen
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Vincenzo Calabrese
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
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7
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Min K, Tae G. Cellular infiltration in an injectable sulfated cellulose nanocrystal hydrogel and efficient angiogenesis by VEGF loading. Biomater Res 2023; 27:28. [PMID: 37038209 PMCID: PMC10084697 DOI: 10.1186/s40824-023-00373-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/30/2023] [Indexed: 04/12/2023] Open
Abstract
BACKGROUND Cellular infiltration and angiogenesis into implanted biomaterial scaffolds are crucial for successful host tissue integration and tissue regeneration. Cellulose nanocrystal (CNC) is a nano-sized cellulose derivative, which can form an injectable physical gel with salts. Sulfate groups of sulfated CNC (CNC-S) can act as a binding domain to various growth factors and cytokines with a heparin-binding domain for sustained release of them. Vascular endothelial growth factor (VEGF) can promote the proliferation of endothelial cells and angiogenesis. In this study, VEGF-loaded CNC-S hydrogel was evaluated as an injectable scaffold that can induce cellular infiltration and angiogenesis. METHODS CNC-S was hydrolyzed to get desulfated CNC (CNC-DS), which was used as a negative control group against CNC-S. Both CNC-S and CNC-DS hydrogels were prepared and compared in terms of biocompatibility and VEGF release. The hydrogels with or without VEGF loading were subcutaneously injected into mice to evaluate the biocompatibility, cellular infiltration, and angiogenesis induction of the hydrogels. RESULTS Both hydrogels possessed similar stability and shear-thinning behavior to be applicable as injectable hydrogels. However, CNC-S hydrogel showed sustained release (until 8 weeks) of VEGF whereas CNC-DS showed a very fast release of VEGF with a large burst. Subcutaneously injected CNC-S hydrogel showed much enhanced cellular infiltration as well as better biocompatibility with milder foreign body response than CNC-DS hydrogel. Furthermore, VEGF-loaded CNC-S hydrogel induced significant angiogenesis inside the hydrogel whereas VEGF-loaded CNC-DS did not. CONCLUSION CNC-S possesses good properties as a biomaterial including injectability, biocompatibility, and allowing cellular infiltration and sustained release of growth factors. VEGF-loaded CNC-S hydrogel exhibited efficient angiogenesis inside the hydrogel. The sulfate group of CNC-S was a key for good biocompatibility and the biological activities of VEGF-loaded CNC hydrogel.
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Affiliation(s)
- Kiyoon Min
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-Gwagiro, Buk-Gu, Gwangju, 61005, Republic of Korea
| | - Giyoong Tae
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-Gwagiro, Buk-Gu, Gwangju, 61005, Republic of Korea.
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8
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Abbasi Moud A, Abbasi Moud A. Flow and assembly of cellulose nanocrystals (CNC): A bottom-up perspective - A review. Int J Biol Macromol 2023; 232:123391. [PMID: 36716841 DOI: 10.1016/j.ijbiomac.2023.123391] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/28/2023]
Abstract
Cellulosic sources, such as lignocellulose-rich biomass, can be mechanically or acid degraded to produce inclusions called cellulose nanocrystals (CNCs). They have several uses in the sectors of biomedicine, photonics, and material engineering because of their biodegradability, renewability, sustainability, and mechanical qualities. The processing and design of CNC-based products are inextricably linked to the rheological behaviour of CNC suspension or in combination with other chemicals, such as surfactants or polymers; in this context, rheology offers a significant link between microstructure and macro scale flow behaviour that is intricately linked to material response in applications. The flow behaviour of CNC items must be properly specified in order to produce goods with value-added characteristics. In this review article, we provide new research on the shear rheology of CNC dispersion and CNC-based hydrogels in the linear and nonlinear regime, with storage modulus values reported to range from ~10-3 to 103 Pa. Applications in technology and material science are also covered simultaneously. We carefully examined the effects of charge density, aspect ratio, concentration, persistence length, alignment, liquid crystal formation, the cause of chirality in CNCs, interfacial behaviour and interfacial rheology, linear and nonlinear viscoelasticity of CNC suspension in bulk and at the interface using the currently available literature.
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Affiliation(s)
- Aref Abbasi Moud
- Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada; Biomedical Engineering Department, AmirKabir University of Technology, P.O. Box 15875/4413, PC36+P45 District 6, Tehran, Tehran Province 1591634311, Iran.
| | - Aliyeh Abbasi Moud
- Biomedical Engineering Department, AmirKabir University of Technology, P.O. Box 15875/4413, PC36+P45 District 6, Tehran, Tehran Province 1591634311, Iran
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9
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Kim M, Kim S, Han N, Lee S, Kim H. Understanding viscoelastic behavior of hybrid nanocellulose film based on rheological and electrostatic observation in blended suspension. Carbohydr Polym 2023; 300:120218. [DOI: 10.1016/j.carbpol.2022.120218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/30/2022] [Accepted: 10/09/2022] [Indexed: 11/11/2022]
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10
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Sun Q, Lutz-Bueno V, Zhou J, Yuan Y, Fischer P. Polymer induced liquid crystal phase behavior of cellulose nanocrystal dispersions. NANOSCALE ADVANCES 2022; 4:4863-4870. [PMID: 36381514 PMCID: PMC9642361 DOI: 10.1039/d2na00303a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/02/2022] [Indexed: 06/16/2023]
Abstract
Cellulose nanocrystals (CNCs) are a promising bio-based material that has attracted significant attention in the fabrication of functional hybrid materials. The rod-like shape and negative surface charge of CNCs enable their rich colloidal behavior, such as a liquid crystalline phase and hydrogel formation that can be mediated by different additives. This study investigates the effect of depletion-induced attraction in the presence of non-absorbing polyethylene glycol (PEG) of different molecular weights in CNC aqueous dispersions, where the polymer molecules deplete the space around particles, apply osmotic pressure and drive the phase transition. Polarized light microscopy (PLM), rheology, small angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are used to characterize the phase behavior over a time period of one month. In our results, pure CNC dispersion shows three typical liquid crystal shear rheology regimes and cholesteric self-assembly behavior. Tactoid nucleation, growth and coalescence are observed microscopically, and eventually the dispersion presents macroscopic phase separation. PEG with lower molecular weight induces weak attractive depletion forces. Tactoid growth is limited, and the whole system turns into a fully nematic phase macroscopically. With PEG of higher molecular weight, attractive depletion force becomes predominant, thus CNC self-assembly is inhibited and nematic hydrogel formation is triggered. Overall, we demonstrate that depletion induced attraction forces by the addition of PEG enable precise tuning of CNC self-assembly and phase behavior with controllable mechanical strength and optical activity. These findings deepen our fundamental understanding of cellulose nanocrystals and advance their application in colloidal systems and nanomaterials.
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Affiliation(s)
- Qiyao Sun
- Department of Health Science and Technology, ETH Zurich 8092 Zurich Switzerland +41 44 632 9710
| | - Viviane Lutz-Bueno
- Department of Health Science and Technology, ETH Zurich 8092 Zurich Switzerland +41 44 632 9710
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | - Jiangtao Zhou
- Department of Health Science and Technology, ETH Zurich 8092 Zurich Switzerland +41 44 632 9710
| | - Ye Yuan
- Department of Health Science and Technology, ETH Zurich 8092 Zurich Switzerland +41 44 632 9710
| | - Peter Fischer
- Department of Health Science and Technology, ETH Zurich 8092 Zurich Switzerland +41 44 632 9710
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Donepezil hydrochloride-reinforced cellulose nanocrystal-aggregated gel structure for long-acting drug delivery. Carbohydr Polym 2022; 296:119887. [DOI: 10.1016/j.carbpol.2022.119887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/28/2022] [Accepted: 07/15/2022] [Indexed: 11/21/2022]
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12
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Bertsch P, Diba M, Mooney DJ, Leeuwenburgh SCG. Self-Healing Injectable Hydrogels for Tissue Regeneration. Chem Rev 2022; 123:834-873. [PMID: 35930422 PMCID: PMC9881015 DOI: 10.1021/acs.chemrev.2c00179] [Citation(s) in RCA: 189] [Impact Index Per Article: 94.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Biomaterials with the ability to self-heal and recover their structural integrity offer many advantages for applications in biomedicine. The past decade has witnessed the rapid emergence of a new class of self-healing biomaterials commonly termed injectable, or printable in the context of 3D printing. These self-healing injectable biomaterials, mostly hydrogels and other soft condensed matter based on reversible chemistry, are able to temporarily fluidize under shear stress and subsequently recover their original mechanical properties. Self-healing injectable hydrogels offer distinct advantages compared to traditional biomaterials. Most notably, they can be administered in a locally targeted and minimally invasive manner through a narrow syringe without the need for invasive surgery. Their moldability allows for a patient-specific intervention and shows great prospects for personalized medicine. Injected hydrogels can facilitate tissue regeneration in multiple ways owing to their viscoelastic and diffusive nature, ranging from simple mechanical support, spatiotemporally controlled delivery of cells or therapeutics, to local recruitment and modulation of host cells to promote tissue regeneration. Consequently, self-healing injectable hydrogels have been at the forefront of many cutting-edge tissue regeneration strategies. This study provides a critical review of the current state of self-healing injectable hydrogels for tissue regeneration. As key challenges toward further maturation of this exciting research field, we identify (i) the trade-off between the self-healing and injectability of hydrogels vs their physical stability, (ii) the lack of consensus on rheological characterization and quantitative benchmarks for self-healing injectable hydrogels, particularly regarding the capillary flow in syringes, and (iii) practical limitations regarding translation toward therapeutically effective formulations for regeneration of specific tissues. Hence, here we (i) review chemical and physical design strategies for self-healing injectable hydrogels, (ii) provide a practical guide for their rheological analysis, and (iii) showcase their applicability for regeneration of various tissues and 3D printing of complex tissues and organoids.
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Affiliation(s)
- Pascal Bertsch
- Department
of Dentistry-Regenerative Biomaterials, Radboud Institute for Molecular
Life Sciences, Radboud University Medical
Center, 6525 EX Nijmegen, The Netherlands
| | - Mani Diba
- Department
of Dentistry-Regenerative Biomaterials, Radboud Institute for Molecular
Life Sciences, Radboud University Medical
Center, 6525 EX Nijmegen, The Netherlands,John
A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States,Wyss
Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02115, United States
| | - David J. Mooney
- John
A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States,Wyss
Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02115, United States
| | - Sander C. G. Leeuwenburgh
- Department
of Dentistry-Regenerative Biomaterials, Radboud Institute for Molecular
Life Sciences, Radboud University Medical
Center, 6525 EX Nijmegen, The Netherlands,
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13
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Carboxylated cellulose nanocrystal films with tunable chiroptical properties. Carbohydr Polym 2022; 289:119442. [DOI: 10.1016/j.carbpol.2022.119442] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/17/2022] [Accepted: 03/30/2022] [Indexed: 11/19/2022]
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Abstract
![]()
Understanding
the
hydrodynamic alignment of colloidal rods in polymer
solutions is pivotal for manufacturing structurally ordered materials.
How polymer crowding influences the flow-induced alignment of suspended
colloidal rods remains unclear when rods and polymers share similar
length scales. We tackle this problem by analyzing the alignment of
colloidal rods suspended in crowded polymer solutions and comparing
that to the case where crowding is provided by additional colloidal
rods in a pure solvent. We find that the polymer dynamics govern the
onset of shear-induced alignment of colloidal rods suspended in polymer
solutions, and the control parameter for the alignment of rods is
the Weissenberg number, quantifying the elastic response of the polymer
to an imposed flow. Moreover, we show that the increasing colloidal
alignment with the shear rate follows a universal trend that is independent
of the surrounding crowding environment. Our results indicate that
colloidal rod alignment in polymer solutions can be predicted on the
basis of the critical shear rate at which polymer coils are deformed
by the flow, aiding the synthesis and design of anisotropic materials.
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Affiliation(s)
- Vincenzo Calabrese
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Stylianos Varchanis
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Simon J. Haward
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Amy Q. Shen
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
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15
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Esmaeili M, George K, Rezvan G, Taheri-Qazvini N, Zhang R, Sadati M. Capillary Flow Characterizations of Chiral Nematic Cellulose Nanocrystal Suspensions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2192-2204. [PMID: 35133841 DOI: 10.1021/acs.langmuir.1c01881] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Studying the flow-induced alignment of anisotropic liquid crystalline materials is of major importance in the 3D printing of advanced architectures. However, in situ characterization and quantitative measurements of local orientations during the 3D printing process are challenging. Here, we report a microfluidic strategy integrated with polarized optical microscopy (POM) to perform the in situ characterization of the alignment of cellulose nanocrystals (CNCs) under the shear-flow condition of the 3D printer's nozzle in the direct ink writing process. To quantify the alignment, we exploited birefringence measurements under white and monochromatic light. We show that the flow-induced birefringence patterns are significantly influenced by the initial structure of the aqueous CNC suspensions. Depending on the CNC concentration and sonication treatment, various structures can form in the CNC suspensions, such as isotropic, chiral nematic (cholesteric), and nematic (gel-like) structures. In the chiral nematic phase, in particular, the shear flow in the microfluidic capillary has a distinct effect on the alignment of the CNC particles. Our experimental results, complemented by hydrodynamic simulations, reveal that at high flow rates (Er ≈ 1000), individual CNC particles align with the flow exhibiting a weak chiral structure. In contrast, at lower flow rates (Er ≈ 241), they display the double-twisted cylinder structure. Understanding the flow effect on the alignment of the chiral liquid crystal can pave the way to designing 3D printed architectures with internal chirality for advanced mechanical and smart photonic applications.
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Affiliation(s)
- Mohsen Esmaeili
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Kyle George
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Gelareh Rezvan
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Nader Taheri-Qazvini
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
- Biomedical Engineering Program, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Rui Zhang
- Department of Physics, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Monirosadat Sadati
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
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16
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Bertsch P, Andrée L, Besheli NH, Leeuwenburgh SC. Colloidal hydrogels made of gelatin nanoparticles exhibit fast stress relaxation at strains relevant for cell activity. Acta Biomater 2022; 138:124-132. [PMID: 34740854 DOI: 10.1016/j.actbio.2021.10.053] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/18/2021] [Accepted: 10/28/2021] [Indexed: 02/02/2023]
Abstract
Viscoelastic properties of hydrogels such as stress relaxation or plasticity have been recognized as important mechanical cues that dictate the migration, proliferation, and differentiation of embedded cells. Stress relaxation rates in conventional hydrogels are usually much slower than cellular processes, which impedes rapid cellularization of these elastic networks. Colloidal hydrogels assembled from nanoscale building blocks may provide increased degrees of freedom in the design of viscoelastic hydrogels with accelerated stress relaxation rates due to their strain-sensitive rheology which can be tuned via interparticle interactions. Here, we investigate the stress relaxation of colloidal hydrogels from gelatin nanoparticles in comparison to physical gelatin hydrogels and explore the particle interactions that govern stress relaxation. Colloidal and physical gelatin hydrogels exhibit comparable rheology at small deformations, but colloidal hydrogels fluidize beyond a critical strain while physical gels remain primarily elastic independent of strain. This fluidization facilitates fast exponential stress relaxation in colloidal gels at strain levels that correspond to strains exerted by cells embedded in physiological extracellular matrices (10-50%). Increased attractive particle interactions result in a higher critical strain and slower stress relaxation in colloidal gels. In physical gels, stress relaxation is slower and mostly independent of strain. Hence, colloidal hydrogels offer the possibility to modulate viscoelasticity via interparticle interactions and obtain fast stress relaxation rates at strains relevant for cell activity. These beneficial features render colloidal hydrogels promising alternatives to conventional monolithic hydrogels for tissue engineering and regenerative medicine. STATEMENT OF SIGNIFICANCE: In the endeavor to design biomaterials that favor cell activity, research has long focused on biochemical cues. Recently, the time-, stress-, and strain-dependent mechanical properties, i.e. viscoelasticity, of biomaterials has been recognized as important factor that dictates cell fate. We herein present the viscoelastic stress relaxation of colloidal hydrogels assembled from gelatin nanoparticles, which show a strain-dependent fluidization at strains relevant for cell activity, in contrast to many commonly used monolithic hydrogels with primarily elastic behavior.
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17
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Tardy BL, Mattos BD, Otoni CG, Beaumont M, Majoinen J, Kämäräinen T, Rojas OJ. Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials. Chem Rev 2021; 121:14088-14188. [PMID: 34415732 PMCID: PMC8630709 DOI: 10.1021/acs.chemrev.0c01333] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Indexed: 12/12/2022]
Abstract
This review considers the most recent developments in supramolecular and supraparticle structures obtained from natural, renewable biopolymers as well as their disassembly and reassembly into engineered materials. We introduce the main interactions that control bottom-up synthesis and top-down design at different length scales, highlighting the promise of natural biopolymers and associated building blocks. The latter have become main actors in the recent surge of the scientific and patent literature related to the subject. Such developments make prominent use of multicomponent and hierarchical polymeric assemblies and structures that contain polysaccharides (cellulose, chitin, and others), polyphenols (lignins, tannins), and proteins (soy, whey, silk, and other proteins). We offer a comprehensive discussion about the interactions that exist in their native architectures (including multicomponent and composite forms), the chemical modification of polysaccharides and their deconstruction into high axial aspect nanofibers and nanorods. We reflect on the availability and suitability of the latter types of building blocks to enable superstructures and colloidal associations. As far as processing, we describe the most relevant transitions, from the solution to the gel state and the routes that can be used to arrive to consolidated materials with prescribed properties. We highlight the implementation of supramolecular and superstructures in different technological fields that exploit the synergies exhibited by renewable polymers and biocolloids integrated in structured materials.
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Affiliation(s)
- Blaise L. Tardy
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Bruno D. Mattos
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Caio G. Otoni
- Department
of Physical Chemistry, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, São Paulo 13083-970, Brazil
- Department
of Materials Engineering, Federal University
of São Carlos, Rod. Washington Luís, km 235, São
Carlos, São Paulo 13565-905, Brazil
| | - Marco Beaumont
- School
of Chemistry and Physics, Queensland University
of Technology, 2 George
Street, Brisbane, Queensland 4001, Australia
- Department
of Chemistry, Institute of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna, A-3430 Tulln, Austria
| | - Johanna Majoinen
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Tero Kämäräinen
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Orlando J. Rojas
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
- Bioproducts
Institute, Department of Chemical and Biological Engineering, Department
of Chemistry and Department of Wood Science, University of British Columbia, 2360 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
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18
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Rosén T, Wang R, He H, Zhan C, Chodankar S, Hsiao BS. Understanding ion-induced assembly of cellulose nanofibrillar gels through shear-free mixing and in situ scanning-SAXS. NANOSCALE ADVANCES 2021; 3:4940-4951. [PMID: 34485817 PMCID: PMC8386416 DOI: 10.1039/d1na00236h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/16/2021] [Indexed: 05/12/2023]
Abstract
During the past decade, cellulose nanofibrils (CNFs) have shown tremendous potential as a building block to fabricate new advanced materials that are both biocompatible and biodegradable. The excellent mechanical properties of the individual CNF can be transferred to macroscale fibers through careful control in hydrodynamic alignment and assembly processes. The optimization of such processes relies on the understanding of nanofibril dynamics during the process, which in turn requires in situ characterization. Here, we use a shear-free mixing experiment combined with scanning small-angle X-ray scattering (scanning-SAXS) to provide time-resolved nanoscale kinetics during the in situ assembly of dispersed cellulose nanofibrils (CNFs) upon mixing with a sodium chloride solution. The addition of monovalent ions led to the transition to a volume-spanning arrested (gel) state. The transition of CNFs is associated with segmental aggregation of the particles, leading to a connected network and reduced Brownian motion, whereby an aligned structure can be preserved. Furthermore, we find that the extensional flow seems to enhance the formation of these segmental aggregates, which in turn provides a comprehensible explanation for the superior material properties obtained in shear-free processes used for spinning filaments from CNFs. This observation clearly highlights the need for different assembly strategies depending on morphology and interactions of the dispersed nanoparticles, where this work can be used as a guide for improved nanomaterial processes.
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Affiliation(s)
- Tomas Rosén
- Department of Chemistry, Stony Brook University Stony Brook New York 11794-3400 USA
- Department of Fiber and Polymer Technology, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
- Wallenberg Wood Science Center, KTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Ruifu Wang
- Department of Chemistry, Stony Brook University Stony Brook New York 11794-3400 USA
| | - HongRui He
- Department of Chemistry, Stony Brook University Stony Brook New York 11794-3400 USA
| | - Chengbo Zhan
- Department of Chemistry, Stony Brook University Stony Brook New York 11794-3400 USA
| | - Shirish Chodankar
- National Synchrotron Light Source II, Brookhaven National Lab Upton NY USA
| | - Benjamin S Hsiao
- Department of Chemistry, Stony Brook University Stony Brook New York 11794-3400 USA
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19
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Munier P, Di A, Hadi SE, Kapuscinski M, Segad M, Bergström L. Assembly of cellulose nanocrystals and clay nanoplatelets studied by time-resolved X-ray scattering. SOFT MATTER 2021; 17:5747-5755. [PMID: 34019065 DOI: 10.1039/d1sm00251a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Time-resolved small-angle X-ray scattering (SAXS) was used to probe the assembly of cellulose nanocrystals (CNC) and montmorillonite (MNT) over a wide concentration range in aqueous levitating droplets. Analysis of the SAXS curves of the one-component and mixed dispersions shows that co-assembly of rod-like CNC and MNT nanoplatelets is dominated by the interactions between the dispersed CNC particles and that MNT promotes gelation and assembly of CNC, which occurred at lower total volume fractions in the CNC:MNT than in the CNC-only dispersions. The CNC dispersions displayed a d ∝ φ-1/2 scaling and a low-q power-law exponent of 2.0-2.2 for volume fractions up to 35%, which indicates that liquid crystal assembly co-exists and competes with gelation.
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Affiliation(s)
- Pierre Munier
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
| | - Andi Di
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
| | - Seyed Ehsan Hadi
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
| | - Martin Kapuscinski
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
| | - Mo Segad
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
| | - Lennart Bergström
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
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20
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Calabrese V, Varchanis S, Haward SJ, Tsamopoulos J, Shen AQ. Structure-property relationship of a soft colloidal glass in simple and mixed flows. J Colloid Interface Sci 2021; 601:454-466. [PMID: 34126412 DOI: 10.1016/j.jcis.2021.05.103] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS Under specific conditions, rod-like cellulose nanocrystals (CNC) can assemble into structurally ordered soft glasses (SGs) with anisotropy that can be controlled by applying shear. However, to achieve full structural control of SGs in real industrial processes, their response to mixed shear and extensional kinematics needs to be determined. We hypothesise that by knowing the shear rheology of the CNC-based soft glass and adopting a suitable constitutive model, it is possible to predict the structure-property relationship of the SG under mixed flows. EXPERIMENTS We use an aqueous suspension with 2 wt% CNC at 25 mM NaCl to form a structurally ordered SG composed of a CNC network containing nematic domains. We combine rheometry and microfluidic experiments with numerical simulations to study the flow properties of the SG in shear, extension, and mixed flow conditions. Extensional flow is investigated in the Optimised Shape Cross-slot Extensional Rheometer (OSCER), where the SG is exposed to shear-free planar elongation. Mixed flow kinematics are investigated in a benchmark microfluidic cylinder device (MCD) where the SG flows past a confined cylinder in a microchannel. FINDINGS The SG in the MCD displays a velocity overshoot (negative wake) and a pronounced CNC alignment downstream of the cylinder. Simulations using the thixotropic elasto-visco-plastic (TEVP) model yield near quantitative agreement of the velocity profiles in simple and mixed flows and capture the structural fingerprint of the material. Our results provide a comprehensive link between the structural behaviour of a CNC-based SG and its mechanistic properties, laying foundations for the development of functional, built-to-order soft materials.
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Affiliation(s)
- Vincenzo Calabrese
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
| | - Stylianos Varchanis
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan; Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, Patras 26500, Greece
| | - Simon J Haward
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
| | - John Tsamopoulos
- Laboratory of Fluid Mechanics and Rheology, Department of Chemical Engineering, University of Patras, Patras 26500, Greece
| | - Amy Q Shen
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan.
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21
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Casado U, Mucci VL, Aranguren MI. Cellulose nanocrystals suspensions: Liquid crystal anisotropy, rheology and films iridescence. Carbohydr Polym 2021; 261:117848. [PMID: 33766344 DOI: 10.1016/j.carbpol.2021.117848] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/05/2021] [Accepted: 02/19/2021] [Indexed: 01/06/2023]
Abstract
The properties of aqueous suspensions of cellulose nanocrystals (CNC) and their casted films are revised. The bio-nanoparticles are briefly introduced, including modifications of the crystals and the suspending media. The formation of CNC-derived liquid crystals (LC) and their resulting rheological behavior are presented. The effects of different variables are addressed: CNC aspect ratio, surface chemistry, concentration, time required for the appearance of an anisotropic phase and addition of other components to the suspension media. The changes on the structure induced by alignment, and by conditions of the drying process are also reported. The optical properties of the films are considered, and the effect of the above variables on the final transparency, iridescence and overall optical response of these bio-inspired photonic materials. Control of the reviewed variables is needed to achieve reliable materials in applications such as sensors, smart inks and papers, transparent flexible supports for electronics, decorative coatings and films.
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Affiliation(s)
- Ulises Casado
- Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), Universidad Nacional de Mar del Plata (UNMdP) - Consejo Nacional de Investigaciones en Ciencia y tecnología (CONICET), Facultad de Ingeniería, Av. Juan B Justo 4302, (7600), Mar del Plata, Argentina
| | - Verónica L Mucci
- Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), Universidad Nacional de Mar del Plata (UNMdP) - Consejo Nacional de Investigaciones en Ciencia y tecnología (CONICET), Facultad de Ingeniería, Av. Juan B Justo 4302, (7600), Mar del Plata, Argentina
| | - Mirta I Aranguren
- Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), Universidad Nacional de Mar del Plata (UNMdP) - Consejo Nacional de Investigaciones en Ciencia y tecnología (CONICET), Facultad de Ingeniería, Av. Juan B Justo 4302, (7600), Mar del Plata, Argentina.
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22
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Kang K, Eremin A. Solvent-dependent morphology and anisotropic microscopic dynamics of cellulose nanocrystals under electric fields. Phys Rev E 2021; 103:032606. [PMID: 33862807 DOI: 10.1103/physreve.103.032606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/03/2021] [Indexed: 11/07/2022]
Abstract
Cellulose nanocrystals (CNCs) are interesting for the construction of biomaterials for energy delivery and packaging purposes. The corresponding processing of CNCs can be optimized through the variation of intercellulose interactions by employing different types of solvents, and thereby varying the degree of cellulose hydrogen bonding. The aim of this work is (i) to show how different types of solvents affect the self-assembled morphology of CNCs, (ii) to study the microscopic dynamics and averaged orientations on the CNCs in aqueous suspensions, including the effect of externally imposed electric fields, and (iii) to explore the nonlinear optical response of CNCs. The homogeneity of self-assembled chiral-nematic phase depends on both the polarity of the solvent and the CNC concentration. The variation of the chiral-nematic pitch length with concentration, as determined from real-space and Fourier images, is found to be strongly solvent dependent. The anisotropic microdynamics of CNCs suspension exhibits two modes, related to diffusion parallel and perpendicular to the (chiral-) nematic director. We have found also the coupling between translational and orientational motion, due to existing correlation length of twisted nematic elasticity. Preliminary second-harmonic generation experiments are performed, which reveal that relatively high field strengths are required to reorient chiral-nematic domains of CNCs.
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Affiliation(s)
- Kyongok Kang
- Forschungszentrum Jülich, Institute of Biological Information Processing, IBI-4:Biomacromolecular Systems and Processes, Jülich 52428, Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Güricke University Magdeburg, Magdeburg 39016, Germany
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23
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Rosén T, Wang R, He H, Zhan C, Chodankar S, Hsiao BS. Shear-free mixing to achieve accurate temporospatial nanoscale kinetics through scanning-SAXS: ion-induced phase transition of dispersed cellulose nanocrystals. LAB ON A CHIP 2021; 21:1084-1095. [PMID: 33514993 PMCID: PMC8323814 DOI: 10.1039/d0lc01048k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/25/2021] [Indexed: 05/25/2023]
Abstract
Time-resolved in situ characterization of well-defined mixing processes using small-angle X-ray scattering (SAXS) is usually challenging, especially if the process involves changes of material viscoelasticity. In specific, it can be difficult to create a continuous mixing experiment without shearing the material of interest; a desirable situation since shear flow both affects nanoscale structures and flow stability as well as resulting in unreliable time-resolved data. Here, we demonstrate a flow-focusing mixing device for in situ nanostructural characterization using scanning-SAXS. Given the interfacial tension and viscosity ratio between core and sheath fluids, the core material confined by sheath flows is completely detached from the walls and forms a zero-shear plug flow at the channel center, allowing for a trivial conversion of spatial coordinates to mixing times. With this technique, the time-resolved gel formation of dispersed cellulose nanocrystals (CNCs) was studied by mixing with a sodium chloride solution. It is observed how locally ordered regions, so called tactoids, are disrupted when the added monovalent ions affect the electrostatic interactions, which in turn leads to a loss of CNC alignment through enhanced rotary diffusion. The demonstrated flow-focusing scanning-SAXS technique can be used to unveil important kinetics during structural formation of nanocellulosic materials. However, the same technique is also applicable in many soft matter systems to provide new insights into the nanoscale dynamics during mixing.
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Affiliation(s)
- Tomas Rosén
- Department of Chemistry, Stony Brook UniversityStony BrookNew York 11794-3400USA
- Department of Fiber and Polymer Technology, KTH Royal Institute of TechnologySE-100 44 StockholmSweden
- Wallenberg Wood Science Center, KTH Royal Institute of TechnologySE-100 44 StockholmSweden
| | - Ruifu Wang
- Department of Chemistry, Stony Brook UniversityStony BrookNew York 11794-3400USA
| | - HongRui He
- Department of Chemistry, Stony Brook UniversityStony BrookNew York 11794-3400USA
| | - Chengbo Zhan
- Department of Chemistry, Stony Brook UniversityStony BrookNew York 11794-3400USA
| | - Shirish Chodankar
- National Synchrotron Light Source II, Brookhaven National LabUptonNYUSA
| | - Benjamin S. Hsiao
- Department of Chemistry, Stony Brook UniversityStony BrookNew York 11794-3400USA
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24
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Calabrese V, Haward SJ, Shen AQ. Effects of Shearing and Extensional Flows on the Alignment of Colloidal Rods. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02155] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Vincenzo Calabrese
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Simon J. Haward
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Amy Q. Shen
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
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25
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Khadem SA, Bagnani M, Mezzenga R, Rey AD. Relaxation dynamics in bio-colloidal cholesteric liquid crystals confined to cylindrical geometry. Nat Commun 2020; 11:4616. [PMID: 32934229 PMCID: PMC7493995 DOI: 10.1038/s41467-020-18421-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 08/12/2020] [Indexed: 12/22/2022] Open
Abstract
Para-nematic phases, induced by unwinding chiral helices, spontaneously relax to a chiral ground state through phase ordering dynamics that are of great interest and crucial for applications such as stimuli-responsive and biomimetic engineering. In this work, we characterize the cholesteric phase relaxation behaviors of β-lactoglobulin amyloid fibrils and cellulose nanocrystals confined into cylindrical capillaries, uncovering two different equilibration pathways. The integration of experimental measurements and theoretical predictions reveals the starkly distinct underlying mechanism behind the relaxation dynamics of β-lactoglobulin amyloid fibrils, characterized by slow equilibration achieved through consecutive sigmoidal-like steps, and of cellulose nanocrystals, characterized by fast equilibration obtained through smooth relaxation dynamics. Particularly, the specific relaxation behaviors are shown to emerge from the order parameter of the unwound cholesteric medium, which depends on chirality and elasticity. The experimental findings are supported by direct numerical simulations, allowing to establish hard-to-measure viscoelastic properties without applying magnetic or electric fields.
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Affiliation(s)
- Sayyed Ahmad Khadem
- Department of Chemical Engineering, McGill University, Montreal, QC, H3A 2B2, Canada
- Quebec Centre for Advanced Materials, Canada (QCAM/CQMF), Montreal, QC, H3A 2K6, Canada
| | - Massimo Bagnani
- Department of Health Sciences and Technology, ETH Zurich, Schmelzbergstrasse 9, Zurich, 8092, Switzerland
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology, ETH Zurich, Schmelzbergstrasse 9, Zurich, 8092, Switzerland
- Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, Zurich, 8093, Switzerland
| | - Alejandro D Rey
- Department of Chemical Engineering, McGill University, Montreal, QC, H3A 2B2, Canada.
- Quebec Centre for Advanced Materials, Canada (QCAM/CQMF), Montreal, QC, H3A 2K6, Canada.
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26
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Bertsch P, Diener M, Adamcik J, Scheuble N, Geue T, Mezzenga R, Fischer P. Correction to Adsorption and Interfacial Layer Structure of Unmodified Nanocrystalline Cellulose at Air/Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1848-1849. [PMID: 32052972 DOI: 10.1021/acs.langmuir.0c00263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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27
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Chu G, Vasilyev G, Qu D, Deng S, Bai L, Rojas OJ, Zussman E. Structural Arrest and Phase Transition in Glassy Nanocellulose Colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:979-985. [PMID: 31927969 PMCID: PMC7704027 DOI: 10.1021/acs.langmuir.9b03570] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/22/2019] [Indexed: 05/31/2023]
Abstract
From drying blood to oil paint, the developing of a glassy phase from colloids is observed on a daily basis. Colloidal glass is solid soft matter that consists of two intertwined phases: a random packed particle network and a fluid solvent. By dispersing charged rod-like cellulose nanoparticles into a water-ethylene glycol cosolvent, here we demonstrate a new kind of colloidal glass with a high liquid crystalline order, namely, two general superstructures with nematic and cholesteric packing states are preserved and jammed inside the glass matrix. During the glass formation process, structural arrest and phase transition occur simultaneously at high particle concentrations, yielding solid-like behavior as well as a frozen liquid crystal texture that is because of caging of the charged colloids through neighboring long-ranged repulsive interactions.
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Affiliation(s)
- Guang Chu
- NanoEngineering
Group, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- Bio-Based
Colloids and Materials, Department of Bioproducts and Biosystems,
School of Chemical Engineering, Aalto University, P.O. Box 16300, Espoo FI-00076, Aalto, Finland
| | - Gleb Vasilyev
- NanoEngineering
Group, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Dan Qu
- NanoEngineering
Group, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Shengwei Deng
- College
of Chemical Engineering, Zhejiang University
of Technology, Hangzhou 310014, China
| | - Long Bai
- Bio-Based
Colloids and Materials, Department of Bioproducts and Biosystems,
School of Chemical Engineering, Aalto University, P.O. Box 16300, Espoo FI-00076, Aalto, Finland
| | - Orlando J. Rojas
- Bio-Based
Colloids and Materials, Department of Bioproducts and Biosystems,
School of Chemical Engineering, Aalto University, P.O. Box 16300, Espoo FI-00076, Aalto, Finland
- Department
of Chemical and Biological Engineering, Chemistry and Wood Science, University of British Columbia, 2360 East Mall, Vancouver BC V6T 1Z3, Canada
| | - Eyal Zussman
- NanoEngineering
Group, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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Bertsch P, Fischer P. Adsorption and interfacial structure of nanocelluloses at fluid interfaces. Adv Colloid Interface Sci 2020; 276:102089. [PMID: 31887576 DOI: 10.1016/j.cis.2019.102089] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 01/12/2023]
Abstract
Nanocelluloses (NCs), more specifically cellulose nanocrystals and nanofibrils, are a green alternative for the stabilization of fluid interfaces. The adsorption of NCs at oil-water interfaces facilitates the formation of stable and biocompatible Pickering emulsions. In contrast, unmodified NCs are not able to stabilize foams. As a consequence, NCs are often hydrophobized by covalent modifications or adsorption of surfactants, allowing also the stabilization of foams or functional inverse, double, and stimuli-responsive emulsions. Although the interfacial stabilization by NCs is readily exploited, the driving force of adsorption and stabilization mechanisms remained long unclear. Here, we summarize the recent advances in the understanding of NC adsorption regarding kinetics, isotherms, and energetic aspects, as well as their interfacial structure, surface coverage, and contact angle. We thereby distinguish unmodified NCs, covalently modified NCs, and surfactant enhanced adsorption.
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29
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Bryant SJ, da Silva MA, Hossain KMZ, Calabrese V, Scott JL, Edler KJ. Deep eutectic solvent in water pickering emulsions stabilised by cellulose nanofibrils. RSC Adv 2020; 10:37023-37027. [PMID: 35521254 PMCID: PMC9057056 DOI: 10.1039/d0ra07575b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 09/29/2020] [Indexed: 12/12/2022] Open
Abstract
Deep eutectic solvent (menthol : dodecanoic acid) in water (30 : 70) emulsions stabilised with partially oxidised cellulose nanoparticles remained stable for 200 days at room temperature. Deep eutectic-based emulsions offer potential for non-aqueous reaction systems, chemical extraction, and controlled release. Pickering emulsions using polysaccharides are less toxic and more stable than surfactant-stabilised emulsions. Deep eutectic solvent in water emulsions stabilised with bio-macromolecules were stable for more than 200 days.![]()
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Affiliation(s)
| | | | | | | | - Janet L. Scott
- Department of Chemistry
- University of Bath
- Bath
- UK
- Centre for Sustainable Chemical Technologies
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30
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Xu Y, Atrens A, Stokes JR. A review of nanocrystalline cellulose suspensions: Rheology, liquid crystal ordering and colloidal phase behaviour. Adv Colloid Interface Sci 2020; 275:102076. [PMID: 31780045 DOI: 10.1016/j.cis.2019.102076] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/16/2019] [Accepted: 11/18/2019] [Indexed: 12/26/2022]
Abstract
Nanocrystalline cellulose (NCC) is a colloidal rigid rod, referred to by various terms in the literature including cellulose whisker (CW) and cellulose nanocrystal (CNC). These charged colloidal rods exhibit complex colloidal phase and rheological behaviours in aqueous suspensions, that are dependent on volume fraction and interparticle forces. A major shortcoming in the literature of NCC is that the dimensions and morphology of NCC particles vary significantly with the type of raw material and manufacturing conditions, which causes inconsistencies in suspension rheology and colloidal behaviours reported between different works. In this review, we consider the theory and experimentally-determined rheological and colloidal phase behaviours of charged rod suspensions in general, with a focus in particular on NCC. Dilute and semi-dilute NCC suspensions are isotropic liquids, in which NCC particles follow diffusional dynamics. The rheology of these isotropic NCC suspensions can be described by theoretical models that account for the effects of rod dimensions and surface charge, including those based on Doi and Edwards' theory. With increasing NCC concentration, the isotropic phase can undergo a transition to a liquid crystalline state (isotropic-nematic transition) or a transition to a dynamically arrested solid (liquid-solid transition). The liquid crystal ordering and gelation/glass transition are of particular interest because they respectively form an ordered structure and allow a solid-like mechanical response at relatively low solids fraction. For conditions at which the isotropic-nematic and liquid-solid transitions coincide, the formation of an anisotropic structure within a soft solid suspension is possible. Investigation of these two competing transitions led to the discovery of liquid crystal re-entrancy and existence of an anisotropic soft solid (liquid crystal hydroglass, LCH). LCH has a biphasic structure with an attractive glass matrix and a co-existing liquid crystal phase, providing similar viscoelastic properties to hydrogels but permitting reversible orientation of the colloidal rods in the liquid crystalline phase by shear forces; i.e. their structural ordering is programmable. The liquid crystal transition and gelation/glass transitions are quantitatively dependent on rod dimensions i.e. respectively proportional to L2D and L/D. Phase transitions in NCC suspensions including liquid crystal re-entrancy and formation of LCH can be fully described as a function of rod dimension, volume fraction and interparticle forces. This behaviour is independent of NCC source, allowing development of a generalised phased diagram in which separately-reported phase transitions converge to consistent phase boundaries. This validates a key hypothesis for the study of NCC suspensions, that variation in NCC concentration and interparticle forces can explain the complex phase behaviours observed within suspensions formulated using NCC obtained from different sources.
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31
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Bergfreund J, Sun Q, Fischer P, Bertsch P. Adsorption of charged anisotropic nanoparticles at oil-water interfaces. NANOSCALE ADVANCES 2019; 1:4308-4312. [PMID: 36134395 PMCID: PMC9419606 DOI: 10.1039/c9na00506d] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/05/2019] [Indexed: 05/04/2023]
Abstract
The adsorption of nanoparticles at fluid interfaces is of profound importance in the field of nanotechnology. Recent developments aim at pushing the boundaries beyond spherical model particles towards more complex shapes and surface chemistries, with particular interest in particles of biological origin. Here, we report on the adsorption of charged, shape-anisotropic cellulose nanocrystals (CNCs) for a wide range of oils with varying chemical structure and polarity. CNC adsorption was found to be independent of the chain length of aliphatic n-alkanes, but strongly dependent on oil polarity. Surface pressures decreased for more polar oils due to lower particle adsorption energies. Nanoparticles were increasingly wetted by polar oils, and interparticle Coulomb interactions across the oil phase thus increase in importance. No surface pressure was measurable and the O/W emulsification capacity ceased for the most polar octanol, suggesting limited CNC adsorption. Further, salt-induced charge screening enhanced CNC adsorption and surface coverage due to lower interparticle and particle-interface electrostatic repulsion. An empiric power law is presented which predicts the induced surface pressure of charged nanoparticles based on the specific oil-water interface tension.
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Affiliation(s)
- Jotam Bergfreund
- Institute of Food Nutrition and Health, ETH Zurich 8092 Zurich Switzerland +41 44 632 85 36
| | - Qiyao Sun
- Institute of Food Nutrition and Health, ETH Zurich 8092 Zurich Switzerland +41 44 632 85 36
| | - Peter Fischer
- Institute of Food Nutrition and Health, ETH Zurich 8092 Zurich Switzerland +41 44 632 85 36
| | - Pascal Bertsch
- Institute of Food Nutrition and Health, ETH Zurich 8092 Zurich Switzerland +41 44 632 85 36
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Kang K, Bertsch P, Fischer P. Coupling of long-wavelength density fluctuations to orientations in cellulose nanocrystal suspensions under external fields. Phys Rev E 2019; 100:052606. [PMID: 31869945 DOI: 10.1103/physreve.100.052606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Indexed: 06/10/2023]
Abstract
Motivated by the development of cellulose-based functional materials, we investigate the microscopic dynamics of suspensions of cellulose nanocrystals (CNCs) at different ionic strengths, both in the absence and in the presence of AC electric fields and for various temperatures. A concentration of 5 wt % of the CNCs is chosen for which the dispersions are in the full chiral-nematic state at low ionic strengths. Dynamic light scattering is used to characterize the wave vector-dependent decay rates of number-density fluctuations. Contrary to an isotropic suspension, the dispersion relations (the wave vector dependence of the correlation-function decay rates) as obtained by means of depolarized light scattering are found to exhibit anomalous behavior. The dispersion relations, both without and with an external field, exhibit minima at small wave vectors, which is attributed to coupling of translational motion to the orientation of the CNCs, shown in the chiral-nematic state. The location of the minima is found to weakly depend on ionic strength and shifts significantly towards larger wave vectors upon applying an external electric field for sufficiently high ionic strengths. Finally, preliminary results are presented for smaller length-scale density fluctuations (at larger wave vectors) as a function of temperature, revealing the anisotropic mobilities in the chiral-nematic state of CNCs.
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Affiliation(s)
- Kyongok Kang
- Forschungszentrum Jülich, Institute of Complex Systems, ICS-3, D-52425 Jülich, Germany
| | - Pascal Bertsch
- Institute of Food Nutrition and Health, ETH Zurich, 8092 Zurich, Switzerland
| | - Peter Fischer
- Institute of Food Nutrition and Health, ETH Zurich, 8092 Zurich, Switzerland
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Bertsch P, Schneider L, Bovone G, Tibbitt MW, Fischer P, Gstöhl S. Injectable Biocompatible Hydrogels from Cellulose Nanocrystals for Locally Targeted Sustained Drug Release. ACS APPLIED MATERIALS & INTERFACES 2019; 11:38578-38585. [PMID: 31573787 DOI: 10.1021/acsami.9b15896] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Injectable hydrogels from biocompatible materials are in demand for tissue engineering and drug delivery systems. Here, we produce hydrogels from mere cellulose nanocrystals (CNCs) by salt-induced charge screening. The injectability of CNC hydrogels was assessed by a combination of shear and capillary rheology, revealing that CNC hydrogels are conveyed via plug flow in capillaries allowing injection with minimal impact on mechanical properties. The potential of CNC hydrogels as drug carriers was elaborated by the in vitro release of the model protein bovine serum albumin (BSA), poorly water soluble tetracycline (TC), and readily soluble doxorubicin (DOX) into physiological saline and simulated gastric juice. For TC, a burst release was observed within 2 days, whereas BSA and DOX both showed a sustained release for 2 weeks. Only DOX was released fully from the hydrogels. The different release patterns were attributed to drug size, solubility, and specific drug-CNC interactions. The biocompatibility of CNC hydrogels and maintained bioactivity of released DOX were confirmed in a HeLa cell assay. The drug release was modulated by the incorporation of sucrose or xanthan gum in CNC hydrogels, whereas altering CNC concentration showed minor effects. The release into simulated gastric juice at pH 2 ceased for BSA due to charge inversion and electrostatic complexation, but not for smaller TC. Thus, CNC hydrogels may act as pH-responsive delivery systems that preserve drugs under gastric conditions followed by pH-triggered release in the duodenum.
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Bertsch P, Fischer P. Interfacial Rheology of Charged Anisotropic Cellulose Nanocrystals at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7937-7943. [PMID: 31090427 DOI: 10.1021/acs.langmuir.9b00699] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Cellulose nanocrystals (CNCs) have received attention as a biological alternative for the stabilization of fluid interfaces, yielding biocompatible and sustainable emulsions, foams, and aerogels. The interfacial behavior of nanoparticles with shape anisotropy and surface charge like CNCs is still poorly understood, although it ultimately dictates the mechanical properties and stability of the macroscopic colloidal material. Here, we report on the linear and nonlinear interfacial dilatational and shear rheology of CNCs at the air-water interface. We observed the formation of viscoelastic CNC layers at comparably low surface coverage, which was attributed to the shape anisotropy of CNCs. Further, the interfacial elasticity of CNC layers can be modulated by salt-induced charge screening, thereby shifting the interplay of repulsive and attractive CNC interactions. CNC layers had a viscous character without salt, followed by increasing viscoelasticity upon salt addition. CNC layers display strain hardening during compression and show a yield stress followed by flow under shear. The observed interfacial behavior is discussed in the context of CNC-stabilized foam and emulsion properties. We conclude that understanding the CNC interfacial behavior may help improve the performance of CNC-stabilized colloidal materials.
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Affiliation(s)
- Pascal Bertsch
- Institute of Food Nutrition and Health , ETH Zurich , 8092 Zurich , Switzerland
| | - Peter Fischer
- Institute of Food Nutrition and Health , ETH Zurich , 8092 Zurich , Switzerland
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