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Kumar R, Dzikonski D, Bekker E, Vornhusen R, Vitali V, Imbrock J, Denz C. Fabrication and mechanical characterization of hydrogel-based 3D cell-like structures. OPTICS EXPRESS 2023; 31:29174-29186. [PMID: 37710723 DOI: 10.1364/oe.496888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/27/2023] [Indexed: 09/16/2023]
Abstract
In this article, we demonstrate the fabrication of 3D cell-like structures using a femtosecond laser-based two-photon polymerization technique. By employing poly(ethylene glycol) diacrylate monomers as a precursor solution, we fabricate 3D hemispheres that resemble morphological and biomechanical characteristics of natural cells. We employ an optical tweezers-based microrheology technique to measure the viscoelastic properties of the precursor solutions inside and outside the structures. In addition, we demonstrate the interchangeability of the precursor solution within fabricated structures without impairing the microstructures. The combination of two-photon polymerization and microrheological measurements by optical tweezers demonstrated here represents a powerful toolbox for future investigations into cell mimic and artificial cell studies.
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Vitali V, Nava G, Corno A, Pezzotti M, Bragheri F, Paiè P, Osellame R, Ortenzi MA, Cristiani I, Minzioni P, Bellini T, Zanchetta G. Yield stress "in a flash": investigation of nonlinearity and yielding in soft materials with an optofluidic microrheometer. SOFT MATTER 2021; 17:3105-3112. [PMID: 33598667 DOI: 10.1039/d0sm02168g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Yield stress materials deform as elastic solids or flow as viscous liquids, depending on the applied stress, which also allows them to trap particles below a certain size or density threshold. To investigate the conditions for such a transition at the microscale, we use an optofluidic microrheometer, based on the scattering of an infrared beam onto a microbead, which reaches forces in the nN scale. We perform creep experiments on a model soft material composed of swollen microgels, determining the limits of linear response and yield stress values, and observe quantitative agreement with bulk measurements. However, the motion of the microbead, both below and above yielding, reflects distinctive microscale features of the surrounding material, whose plastic rearrangements were investigated by us using small, passive tracers.
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Affiliation(s)
- Valerio Vitali
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, 27100 Pavia, Italy
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Vitali V, Nava G, Zanchetta G, Bragheri F, Crespi A, Osellame R, Bellini T, Cristiani I, Minzioni P. Integrated Optofluidic Chip for Oscillatory Microrheology. Sci Rep 2020; 10:5831. [PMID: 32242060 PMCID: PMC7118116 DOI: 10.1038/s41598-020-62628-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/05/2020] [Indexed: 11/24/2022] Open
Abstract
We propose and demonstrate an on-chip optofluidic device allowing active oscillatory microrheological measurements with sub-μL sample volume, low cost and high flexibility. Thanks to the use of this optofluidic microrheometer it is possible to measure the viscoelastic properties of complex fluids in the frequency range 0.01-10 Hz at different temperatures. The system is based on the optical forces exerted on a microbead by two counterpropagating infrared laser beams. The core elements of the optical part, integrated waveguides and an optical modulator, are fabricated by fs-laser writing on a glass substrate. The system performance is validated by measuring viscoelastic solutions of aqueous worm-like micelles composed by Cetylpyridinium Chloride (CPyCl) and Sodium Salicylate (NaSal).
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Affiliation(s)
- Valerio Vitali
- University of Pavia, Dept. of Electrical, Computer and Biomedical Engineering, Pavia, 27100, Italy
| | - Giovanni Nava
- University of Milano, Dept. of Medical Biotechnology and Translational Medicine, Milano, 20129, Italy
| | - Giuliano Zanchetta
- University of Milano, Dept. of Medical Biotechnology and Translational Medicine, Milano, 20129, Italy
| | - Francesca Bragheri
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche (IFN-CNR), Milano, 20133, Italy
| | - Andrea Crespi
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche (IFN-CNR), Milano, 20133, Italy
- Dipartimento di Fisica, Politecnico di Milano, Milano, 20133, Italy
| | - Roberto Osellame
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche (IFN-CNR), Milano, 20133, Italy
- Dipartimento di Fisica, Politecnico di Milano, Milano, 20133, Italy
| | - Tommaso Bellini
- University of Milano, Dept. of Medical Biotechnology and Translational Medicine, Milano, 20129, Italy
| | - Ilaria Cristiani
- University of Pavia, Dept. of Electrical, Computer and Biomedical Engineering, Pavia, 27100, Italy
| | - Paolo Minzioni
- University of Pavia, Dept. of Electrical, Computer and Biomedical Engineering, Pavia, 27100, Italy.
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Chen CJ, Chen WL, Phong PH, Chuang HS. Investigation of Micro-volume Viscosity with Janus Microbeads Based on Rotational Brownian Motion. SENSORS 2019; 19:s19051217. [PMID: 30857368 PMCID: PMC6427369 DOI: 10.3390/s19051217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 12/14/2022]
Abstract
Viscosity is an important property of liquids. A viscosity change of aqueous substances that deviates from their normal levels usually implies a compromise in quality due to degradation or microorganism proliferation. Monitoring of macro-scale viscosity can be simply realized by various conventional tools, such as rotational viscometers, capillary tubes, falling bodies, and so forth. Nevertheless, today, micro-volume viscosity measurement remains a challenging endeavor, resulting in rare, expensive, or difficult-to-obtain samples not very well studied. For this reason, a novel technique for micro-viscosity based on rotational Brownian motion is presented in this paper. Janus microbeads were made by coating fluorescent polystyrene beads with gold film. Taking advantage of the bead configuration of half gold/half fluorescence, the rotational Brownian signal was expressed in terms of blinking fluorescent intensity. The characteristic correlation time was derived from the blinking intensity of trace amounts of a selected medium over a certain time period, and results were correlated with viscosity. Given a volume of only 2 μL for each measurement, calibration of a series of glycerol–water mixtures (100%–1% (v/v) water content) yielded good agreement with the expected viscosity predictions over the range of 0.8–574.8 cP. Five common oil products, including lubricant oil, baby oil, food oil, olive oil, and motor oil, were further investigated to demonstrate the feasibility and practicability of the proposed technique. Data measured by the rotational Brownian motion-based diffusometer were comparable with those measured by a commercial rotational viscometer. The method also explicitly showed viscosity degradation after the oils were heated at a high temperature of over 100 °C for 10 min. Evaluation proved the proposed Janus microbead-enabled rotational diffusometric technique to be a promising approach for rapid and micro-scale viscosity measurement.
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Affiliation(s)
- Chun-Jui Chen
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
| | - Wei-Long Chen
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
| | - Pham Hong Phong
- Institute of Chemistry, Vietnam Academy of Science and Technology, Hanoi 1000, Vietnam.
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi 1000, Vietnam.
| | - Han-Sheng Chuang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
- Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan.
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Nava G, Yang T, Vitali V, Minzioni P, Cristiani I, Bragheri F, Osellame R, Bethge L, Klussmann S, Paraboschi EM, Asselta R, Bellini T. Newtonian to non-newtonian fluid transition of a model transient network. SOFT MATTER 2018; 14:3288-3295. [PMID: 29691545 DOI: 10.1039/c8sm00373d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The viscosity of gel-forming fluids is notoriously complex and its study can benefit from new model systems that enable a detailed control of the network features. Here we use a novel and simple microfluidic-based active microrheology approach to study the transition from Newtonian to non-Newtonian behavior in a DNA hydrogel whose structure, connectivity, density of bonds, bond energy and kinetics are strongly temperature dependent and well known. In a temperature range of 15 °C, the system reversibly and continuously transforms from a Newtonian dispersion of low-valence nanocolloids into a strongly shear-thinning fluid, passing through a set of intermediate states where it behaves as a power-law fluid. We demonstrate that the knowledge of network topology and bond free energy enables to quantitatively predict the observed behavior using established rheology models.
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Affiliation(s)
- Giovanni Nava
- Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129 Milano, Italy.
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Paiè P, Zandrini T, Vázquez RM, Osellame R, Bragheri F. Particle Manipulation by Optical Forces in Microfluidic Devices. MICROMACHINES 2018; 9:E200. [PMID: 30424133 PMCID: PMC6187572 DOI: 10.3390/mi9050200] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/18/2018] [Accepted: 04/20/2018] [Indexed: 01/09/2023]
Abstract
Since the pioneering work of Ashkin and coworkers, back in 1970, optical manipulation gained an increasing interest among the scientific community. Indeed, the advantages and the possibilities of this technique are unsubtle, allowing for the manipulation of small particles with a broad spectrum of dimensions (nanometers to micrometers size), with no physical contact and without affecting the sample viability. Thus, optical manipulation rapidly found a large set of applications in different fields, such as cell biology, biophysics, and genetics. Moreover, large benefits followed the combination of optical manipulation and microfluidic channels, adding to optical manipulation the advantages of microfluidics, such as a continuous sample replacement and therefore high throughput and automatic sample processing. In this work, we will discuss the state of the art of these optofluidic devices, where optical manipulation is used in combination with microfluidic devices. We will distinguish on the optical method implemented and three main categories will be presented and explored: (i) a single highly focused beam used to manipulate the sample, (ii) one or more diverging beams imping on the sample, or (iii) evanescent wave based manipulation.
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Affiliation(s)
- Petra Paiè
- Istituto di Fotonica e Nanotecnlogie IFN-CNR, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
| | - Tommaso Zandrini
- Istituto di Fotonica e Nanotecnlogie IFN-CNR, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
| | - Rebeca Martínez Vázquez
- Istituto di Fotonica e Nanotecnlogie IFN-CNR, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
| | - Roberto Osellame
- Istituto di Fotonica e Nanotecnlogie IFN-CNR, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
| | - Francesca Bragheri
- Istituto di Fotonica e Nanotecnlogie IFN-CNR, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
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