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Microelectromechanical System-Based Sensing Arrays for Comparative in Vitro Nanotoxicity Assessment at Single Cell and Small Cell-Population Using Electrochemical Impedance Spectroscopy Pratikkumar Shah,† Xuena Zhu,† Xueji Zhang,‡ Jin He,§ and Chen-zhong Li*,† †
Nanobioengineering/Bioelectronics Laboratory, Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, Miami, Florida 33174, United States ‡ Research Center for Bioengineering and Sensing Technology, University of Science and Technology Beijing, 100083, P. R. China § Department of Physics, Florida International University, Miami, Florida 33199, United States
ABSTRACT: The traditional in vitro nanotoxicity assessment approaches are conducted on a monolayer of cell culture. However, to study a cell response without interference from the neighbor cells, a single cell study is necessary; especially in cases of neuronal, cancerous, and stem cells, wherein an individual cell’s fate is often not explained by the whole cell population. Nonetheless, a single cell does not mimic the actual in vivo environment and lacks important information regarding cell communication with its microenvironment. Both a single cell and a cell population provide important and complementary information about cells’ behaviors. In this research, we explored nanotoxicity assessment on a single cell and a small cell population using electrochemical impedance spectroscopy and a microelectromechanical system (MEMS) device. We demonstrated a controlled capture of PC12 cells in different-sized microwells (to capture a different number of cells) using a combined method of surface functionalization and dielectrophoresis. The present approach provides a rapid nanotoxicity response as compared to other conventional approaches. This is the first study, to our knowledge, which demonstrates a comparative response of a single cell and small cell colonies on the same MEMS platform, when exposed to metaloxide nanoparticles. We demonstrated that the microenvironment of a cell is also accountable for cells’ behaviors and their responses to nanomaterials. The results of this experimental study open up a new hypothesis to be tested for identifying the role of cell communication in spreading toxicity in a cell population. KEYWORDS: nanotoxicity, single cell, impedance spectroscopy, cell-communication, MEMS
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proper guidelines for handling of nanomaterials and mitigating their potential risks are still unknown, increased use of nanomaterials creates a higher possibility of human and environmental exposure; therefore, there is a clear need to improve the nanomaterial risk assessment, especially by using early detection.4 Nanomaterials-related toxicity is dependent on several factors such as material composition, size, shape, and dosage of nanoparticles, surface charge and reactivity of
wide use of nanoparticles (NPs) raises the concern and fear regarding potential risks to workers’ safety, human health, and environmental contamination.1 The unique physicochemical properties of nanomaterials, such as small size, large surface area, and high reactivity may possess unknown bioactivity upon interaction with cellular/subcellular components.2 In fact, many health disorders such as asthma, bronchitis, pulmonary fibrosis, emphysema, and lung cancer, as well as cardiovascular diseases such as arteriosclerosis, blood clots, and arrhythmia, along with neurodegenerative diseases such as Parkinson’s and Alzheimer’s are associated with inhalation of nanomaterials (including air dust).3 Although © 2016 American Chemical Society
Received: November 24, 2015 Accepted: February 10, 2016 Published: February 10, 2016 5804
DOI: 10.1021/acsami.5b11409 ACS Appl. Mater. Interfaces 2016, 8, 5804−5812
Research Article
ACS Applied Materials & Interfaces nanomaterials, and the cell types with which it interacts.5 In the present scenario, when there is a large matrix of nanomaterials with diverse properties to be evaluated for toxicity, the in vivo approach would be expensive and time-consuming and would present ethical concerns. In contrast, in vitro models provide rapid, effective, and economical means to assess nanomaterials for a number of toxicological end points.6 There are several in vitro approaches to study nanotoxicity that require cell labeling, however, defied by interference of the dye with nanomaterials producing false results, in addition to being limited by end-point measurements which lacks dynamic information.4 The inconsistencies of available in vitro methodologies have posed a challenge to develop new, rapid, and dynamic approaches to evaluate nanomaterial toxicity.7 Labelfree, electrochemical nanotoxicity assessment approaches, such as impedance spectroscopy and amperometry, have been used for bulk assay and a single-cell measurement, respectively. MEMS-based technologies are in use for multiplex assays for several toxic material findings and drug discoveries. However, their use for nanomaterial toxicity is new. A microfluidic chipbased approach is becoming the latest trend in nanotoxicity evaluation after extensive application in biosensing, drug discovery, and stem-cell research.4 Our lab has invested to develop a chip-based approach for providing dynamic information about nanomaterials’ effect on cells.8−12 A few other research groups have also used chip-based platforms exclusively for nanomaterial toxicity studies. For instance, Albanese et al.13 recently discussed the NPs transport kinetics and their tissue accumulation based on different size and surface modifications, in a tumor spheroid mounted on a microfluidic chip. Kim et al.14 had examined the cytotoxicity of mesoporous silica NPs (
