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Zhang S, Felthaus O, Prantl L, Ma N, Machatschek R. Continuous protein-density gradients: A new approach to correlate physical cues with cell response. PNAS NEXUS 2024; 3:pgae202. [PMID: 38840799 PMCID: PMC11152205 DOI: 10.1093/pnasnexus/pgae202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 05/07/2024] [Indexed: 06/07/2024]
Abstract
To assess cellular behavior within heterogeneous tissues, such as bone, skin, and nerves, scaffolds with biophysical gradients are required to adequately replicate the in vivo interaction between cells and their native microenvironment. In this study, we introduce a strategy for depositing ultrathin films comprised of laminin-111 with precisely controlled biophysical gradients onto planar substrates using the Langmuir-Blodgett (LB) technique. The gradient is created by controlled desynchronization of the barrier compression and substrate withdrawal speed during the LB deposition process. Characterization of the films was performed using techniques such as atomic force microscopy and confocal fluorescence microscopy, enabling the comprehensive analysis of biophysical parameters along the gradient direction. Furthermore, human adipose-derived stem cells were seeded onto the gradient films to investigate the influence of protein density on cell attachment, showing that the distribution of the cells can be modulated by the arrangement of the laminin at the air-water interface. The presented approach not only allowed us to gain insights into the intricate interplay between biophysical cues and cell behavior within complex tissue environments, but it is also suited as a screening approach to determine optimal protein concentrations to achieve a target cellular output.
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Affiliation(s)
- Shanshan Zhang
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
- Helmholtz-Zentrum Hereon, Institute of Active Polymers, Kantstrasse 55, 14513 Teltow, Germany
| | - Oliver Felthaus
- Department of Plastic Surgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Lukas Prantl
- Department of Plastic Surgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Nan Ma
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
- Helmholtz-Zentrum Hereon, Institute of Sustainable Materials, Kantstrasse 55, 14513 Teltow, Germany
| | - Rainhard Machatschek
- Helmholtz-Zentrum Hereon, Institute of Active Polymers, Kantstrasse 55, 14513 Teltow, Germany
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Lin L, Dang H, Zhu R, Liu Y, You H. Effects of Side Profile on Acoustic Streaming by Oscillating Microstructures in Channel. MICROMACHINES 2022; 13:mi13091439. [PMID: 36144062 PMCID: PMC9504731 DOI: 10.3390/mi13091439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 06/01/2023]
Abstract
In microchannels, microstructure-induced acoustic streaming can be achieved at low frequencies, providing simple platforms for biomedicine and microfluidic manipulation. Nowadays, microstructures are generally fabricated by photolithography or soft photolithography. Existing studies mainly focused on the projection plane, while ignoring the side profile including microstructure's sidewall and channel's upper wall. Based on the perturbation theory, the article focuses on the effect of microstructure's sidewall errors caused by machining and the viscous dissipation of upper wall on the streaming. We discovered that the side profile parameters, particularly the gap (gap g between the top of the structure and the upper wall of the channel), have a significant impact on the maximum velocity, mode, and effective area of the streaming.To broaden the applicability, we investigated boundary layer thickness parameters including frequency and viscosity. Under different thickness parameters, the effects of side profile parameters on the streaming are similar. But the maximum streaming velocity is proportional to the frequency squared and inversely proportional to the viscosity. Besides, the ratio factor θ of the maximum streaming velocity to the vibration velocity is affected by the side profile parameter gap g and sidewall profile angle α.
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Affiliation(s)
- Lin Lin
- Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, China
- School of Mechanical Engineering, Guangxi University, Nanning 530004, China
- Guangxi Key Lab of Manufacturing System and Advanced Manufacturing Technology, Nanning 530003, China
| | - Haojie Dang
- Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, China
- School of Mechanical Engineering, Guangxi University, Nanning 530004, China
- Guangxi Key Lab of Manufacturing System and Advanced Manufacturing Technology, Nanning 530003, China
| | - Rongxin Zhu
- Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, China
- School of Mechanical Engineering, Guangxi University, Nanning 530004, China
- Guangxi Key Lab of Manufacturing System and Advanced Manufacturing Technology, Nanning 530003, China
| | - Ying Liu
- Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, China
- Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, Guangxi University, Nanning 530004, China
| | - Hui You
- Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning 530004, China
- School of Mechanical Engineering, Guangxi University, Nanning 530004, China
- Guangxi Key Lab of Manufacturing System and Advanced Manufacturing Technology, Nanning 530003, China
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Biocompatibility of SU-8 and Its Biomedical Device Applications. MICROMACHINES 2021; 12:mi12070794. [PMID: 34357204 PMCID: PMC8304786 DOI: 10.3390/mi12070794] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 11/16/2022]
Abstract
SU-8 is an epoxy-based, negative-tone photoresist that has been extensively utilized to fabricate myriads of devices including biomedical devices in the recent years. This paper first reviews the biocompatibility of SU-8 for in vitro and in vivo applications. Surface modification techniques as well as various biomedical applications based on SU-8 are also discussed. Although SU-8 might not be completely biocompatible, existing surface modification techniques, such as O2 plasma treatment or grafting of biocompatible polymers, might be sufficient to minimize biofouling caused by SU-8. As a result, a great deal of effort has been directed to the development of SU-8-based functional devices for biomedical applications. This review includes biomedical applications such as platforms for cell culture and cell encapsulation, immunosensing, neural probes, and implantable pressure sensors. Proper treatments of SU-8 and slight modification of surfaces have enabled the SU-8 as one of the unique choices of materials in the fabrication of biomedical devices. Due to the versatility of SU-8 and comparative advantages in terms of improved Young’s modulus and yield strength, we believe that SU-8-based biomedical devices would gain wider proliferation among the biomedical community in the future.
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Vernekar VN, LaPlaca MC. 3-D multi-electrode arrays detect early spontaneous electrophysiological activity in 3-D neuronal-astrocytic co-cultures. Biomed Eng Lett 2020; 10:579-591. [PMID: 33194249 DOI: 10.1007/s13534-020-00166-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/20/2020] [Accepted: 07/20/2020] [Indexed: 12/01/2022] Open
Abstract
Three-dimensional (3-D) neural cultures represent a promising platform for studying disease and drug screening. Tools and methodologies for measuring the electrophysiological function in these cultures are needed. Therefore, the purpose of this work was primarily to develop a methodology to interface engineered 3-D dissociated neural cultures with commercially available 3-D multi-electrode arrays (MEAs) reliably over 3 weeks to enable the recording of their electrophysiological activity. We further compared the functional output of these cultures to their structural and synaptic network development over time. We reliably interfaced a primary rodent neuron-astrocyte (2:1) 3-D co-culture (2500 cells/mm3 plating cell density) in Matrigel™ (7.5 mg/mL) that was up to 750 µm thick (30-40 cell-layers) with spiked 3-D MEAs while maintaining high viability. Using these MEAs we successfully recorded the spontaneous development of neural network-level electrophysiological activity and measured the development of putative synapses and neuronal maturation in these co-cultures using immunocytochemistry over 3 weeks in vitro. Planar (2-D) MEAs interfaced with these cultures served as recording controls. Neurons within this interfaced 3-D culture-MEA system exhibited considerable neurite outgrowth, networking, neuronal maturation, synaptogenesis, and culture-wide spontaneous firing of synchronized spikes and bursts of action potentials. Network-wide spikes and synchronized bursts increased rapidly (first detected at 2 days) during the first week in culture, plateaued during the second week, and reduced slightly in the third week, while maintaining high viability throughout the 3-week culturing period. Early electrophysiology activity occurred prior to neuronal process maturation and significant synaptic density increases in the second week. We successfully interfaced 3-D neural co-cultures with 3-D MEAs and recorded the electrophysiological activity of these cultures over 3 weeks. The initial period of rapid increase in electrophysiological activity, followed by a period of neuronal maturation and high-level of synapse formation in these cultures suggests a developmental homeostatic process. This methodology can enable future applications both in fundamental investigations of neural network behavior and in translational studies involving drug testing and neural interfacing.
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Affiliation(s)
- Varadraj N Vernekar
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Institute of Bioengineering and Bioscience, Georgia Institute of Technology, 313 Ferst Dr., Atlanta, GA 30332-0535 USA
| | - Michelle C LaPlaca
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Institute of Bioengineering and Bioscience, Georgia Institute of Technology, 313 Ferst Dr., Atlanta, GA 30332-0535 USA
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Ju J, Hu N, Cairns DM, Liu H, Timko BP. Photo-cross-linkable, insulating silk fibroin for bioelectronics with enhanced cell affinity. Proc Natl Acad Sci U S A 2020; 117:15482-15489. [PMID: 32571918 PMCID: PMC7376572 DOI: 10.1073/pnas.2003696117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Bioelectronic scaffolds that support devices while promoting tissue integration could enable tissue hybrids with augmented electronic capabilities. Here, we demonstrate a photo-cross-linkable silk fibroin (PSF) derivative and investigate its structural, electrical, and chemical properties. Lithographically defined PSF films offered tunable thickness and <1-µm spatial resolution and could be released from a relief layer yielding freestanding scaffolds with centimeter-scale uniformity. These constructs were electrically insulating; multielectrode arrays with PSF-passivated interconnects provided stable electrophysiological readouts from HL-1 cardiac model cells, brain slices, and hearts. Compared to SU8, a ubiquitous biomaterial, PSF exhibited superior affinity toward neurons which we attribute to its favorable surface charge and enhanced attachment of poly-d-lysine adhesion factors. This finding is of significant importance in bioelectronics, where tight junctions between devices and cell membranes are necessary for electronic communication. Collectively, our findings are generalizable to a variety of geometries, devices, and tissues, establishing PSF as a promising bioelectronic platform.
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Affiliation(s)
- Jie Ju
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155
- Key Laboratory for Special Functional Materials, Ministry of Education, Henan University, Kaifeng 475004, China
| | - Ning Hu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-Sen University, Guangzhou 510275, China
| | - Dana M Cairns
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155
| | - Haitao Liu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155
- School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China
| | - Brian P Timko
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155;
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Kidwell DA, Lee WK, Perkins K, Gilpin KM, O'Shaughnessy TJ, Robinson JT, Sheehan PE, Mulvaney SP. Chemistries for Making Additive Nanolithography in OrmoComp Permissive for Cell Adhesion and Growth. ACS APPLIED MATERIALS & INTERFACES 2019; 11:19793-19798. [PMID: 31045352 DOI: 10.1021/acsami.9b04096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-photon lithography allows writing of arbitrary nanoarchitectures in photopolymers. This design flexibility opens almost limitless possibilities for biological studies, but the acrylate-based polymers frequently used do not allow for adhesion and growth of some types of cells. Indeed, we found that lithographically defined structures made from OrmoComp do not support E18 murine cortical neurons. We reacted OrmoComp structures with several diamines, thereby rendering the surfaces directly permissive for neuron attachment and growth by presenting a surface coating similar to the traditional cell biology coating achieved with poly-d-lysine (PDL) and laminin. However, in contrast to PDL-laminin coatings that cover the entire surface, the amine-terminated OrmoComp structures are orthogonally modified in deference to the surrounding glass or plastic substrate, adding yet another design element for advanced biological studies.
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Affiliation(s)
| | | | | | - Kathleen M Gilpin
- American Society for Engineering Education (ASEE) Post-Doctoral Fellow at US Naval Research Laboratory , Washington, DC 20375 , United States
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Fox CB, Chirra HD, Desai TA. Planar bioadhesive microdevices: a new technology for oral drug delivery. Curr Pharm Biotechnol 2015; 15:673-83. [PMID: 25219863 DOI: 10.2174/1389201015666140915152706] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 06/01/2014] [Accepted: 06/23/2014] [Indexed: 12/12/2022]
Abstract
The oral route is the most convenient and least expensive route of drug administration. Yet, it is accompanied by many physiological barriers to drug uptake including low stomach pH, intestinal enzymes and transporters, mucosal barriers, and high intestinal fluid shear. While many drug delivery systems have been developed for oral drug administration, the physiological components of the gastro intestinal tract remain formidable barriers to drug uptake. Recently, microfabrication techniques have been applied to create micron-scale devices for oral drug delivery with a high degree of control over microdevice size, shape, chemical composition, drug release profile, and targeting ability. With precise control over device properties, microdevices can be fabricated with characteristics that provide increased adhesion for prolonged drug exposure, unidirectional release which serves to avoid luminal drug loss and enhance drug permeation, and protection of a drug payload from the harsh environment of the intestinal tract. Here we review the recent developments in microdevice technology and discuss the potential of these devices to overcome unsolved challenges in oral drug delivery.
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Affiliation(s)
| | | | - Tejal A Desai
- 1700 4th Street, Byers Hall 204, Box 2520, San Francisco, CA 94158, USA.
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Jorfi M, Skousen JL, Weder C, Capadona JR. Progress towards biocompatible intracortical microelectrodes for neural interfacing applications. J Neural Eng 2014; 12:011001. [PMID: 25460808 DOI: 10.1088/1741-2560/12/1/011001] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To ensure long-term consistent neural recordings, next-generation intracortical microelectrodes are being developed with an increased emphasis on reducing the neuro-inflammatory response. The increased emphasis stems from the improved understanding of the multifaceted role that inflammation may play in disrupting both biologic and abiologic components of the overall neural interface circuit. To combat neuro-inflammation and improve recording quality, the field is actively progressing from traditional inorganic materials towards approaches that either minimizes the microelectrode footprint or that incorporate compliant materials, bioactive molecules, conducting polymers or nanomaterials. However, the immune-privileged cortical tissue introduces an added complexity compared to other biomedical applications that remains to be fully understood. This review provides a comprehensive reflection on the current understanding of the key failure modes that may impact intracortical microelectrode performance. In addition, a detailed overview of the current status of various materials-based approaches that have gained interest for neural interfacing applications is presented, and key challenges that remain to be overcome are discussed. Finally, we present our vision on the future directions of materials-based treatments to improve intracortical microelectrodes for neural interfacing.
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Affiliation(s)
- Mehdi Jorfi
- Adolphe Merkle Institute, University of Fribourg, Rte de l'Ancienne Papeterie, CH-1723 Marly, Switzerland
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Contact printing of arrayed microstructures. Anal Bioanal Chem 2010; 397:3377-85. [PMID: 20425106 DOI: 10.1007/s00216-010-3728-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 04/06/2010] [Accepted: 04/06/2010] [Indexed: 12/16/2022]
Abstract
A novel contact printing method utilizing a sacrificial layer of polyacrylic acid (PAA) was developed to selectively modify the upper surfaces of arrayed microstructures. The method was characterized by printing polystyrene onto SU-8 microstructures to create an improved substrate for a cell-based microarray platform. Experiments measuring cell growth on SU-8 arrays modified with polystyrene and fibronectin demonstrated improved growth of NIH 3T3 (93% vs. 38%), HeLa (97% vs. 77%), and HT1080 (76% vs. 20%) cells relative to that for the previously used coating method. In addition, use of the PAA sacrificial layer permitted the printing of functionalized polystyrene, carboxylate polystyrene nanospheres, and silica nanospheres onto the arrays in a facile manner. Finally, a high concentration of extracellular matrix materials (ECM), such as collagen (5 mg/mL) and gelatin (0.1%), was contact-printed onto the array structures using as little as 5 microL of the ECM reagent and without the formation of a continuous film bridge across the microstructures. Murine embryonic stem cells cultured on arrays printed with this gelatin hydrogel remained in an undifferentiated state indicating an adequate surface gelatin layer to maintain these cells over time.
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