Electric Cell-Substrate Sensing for Real-Time Evaluation of Metal-Organic Framework Toxicological Profiles

Summary

The following study evaluates the toxicological profile of a selected metal-organic framework utilizing electric cell-substrate impedance sensing (ECIS), a real-time, high-throughput screening technique.

Abstract

Metal-organic frameworks (MOFs) are hybrids formed through the coordination of metal ions and organic linkers in organic solvents. The implementation of MOFs in biomedical and industrial applications has led to concerns regarding their safety. Herein, the profile of a selected MOF, a zeolitic imidazole framework, was evaluated upon exposure to human lung epithelial cells. The platform for evaluation was a real-time technique (i.e., electric cell-substrate impedance sensing [ECIS]). This study identifies and discusses some of the deleterious effects of the selected MOF on the exposed cells. Furthermore, this study demonstrates the benefits of using the real-time method versus other biochemical assays for comprehensive cell evaluations. The study concludes that observed changes in cell behavior could hint at possible toxicity induced upon exposure to MOFs of different physicochemical characteristics and the dosage of those frameworks being used. By understanding changes in cell behavior, one foresees the ability to improve safe-by-design strategies of MOFs to be used for biomedical applications by specifically tailoring their physicochemical characteristics.

Introduction

Metal-organic frameworks (MOFs) are hybrids formed through the combination of metal ions and organic linkers^1,2 in organic solvents. Due to the variety of such combinations, MOFs possess structural diversity³, tunable porosity, high thermal stability, and high surface areas^4,5. Such characteristics make them attractive candidates in a variety of applications, from gas storage^6,7 to catalysis^8,9, and from contrast....

Protocol

1. ZIF-8 synthesis

1. For the purpose of this example, use a 1:10:100 (metal:linker:solvent) mass ratio to synthesize the ZIF-8. For this, measure out zinc nitrate hexahydrate, and record the measurement. Utilize the example mass ratio to calculate the amount needed for the linker, 2-methylimidazole, and the solvent (i.e., methanol).
2. Place the zinc nitrate hexahydrate and linker into two different glass vials. Add half of the calculated amount of methanol to the zinc nitrate hexahydrat.......

Discussion

Previous analysis showed that ECIS could be used to assess the behavior of cells exposed to analytes (i.e., carbon nanotubes³⁵, drugs⁴³, or nanoclays¹⁶). Furthermore, Stueckle et al. used ECIS to evaluate the toxicity of BEAS-2B cells exposed to nanoclays and their byproducts and found that the cellular behavior and attachment were dependent on the physicochemical characteristics of such materials⁴². Herein, we proposed to det.......

Materials

Name	Company	Catalog Number	Comments
4-[3-(4-idophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1 assay)	Roche	5015944001
0.25% Trypsin-EDTA (1x)	Gibco	25255-056
100 mm plates	Corning	430167
1300 Series A2 biofume hood	Thermo Scientific	323TS
2510 Branson bath sonicator	Process Equipment & Supply, Inc.	251OR-DTH
2-methylimidazole, 97%	Alfa Aesar	693-98-1
5 mL sterile microtube	Argos Technologies	T2076S-CA
50 mL  tubes	Falcon	352098
96W10idf well plates	Applied Biophysics	96W10idf PET
96-well plates	Fisherbrand	FB012931
Biorender	Biorender	N/A
Countess cell counting chamber slides	Invitrogen	C10283
Countess II FL automated cell counter	Life Technologies	C0916-186A-0303
Denton Desk V sputter and carbon coater	Denton Vacuum	N/A
Dimethly sulfoxide	Corning	25-950-CQC
DPBS/Modified	Cytiva	SH30028.02
Dulbecco's modified Eagle medium	Corning	10-014-CV
ECIS-ZΘ	Applied Biophysics	ABP 1129
Excel	Microsoft	Version 2301
Falcon tubes (15 mL)	Corning	352196
Fetal bovine serum	Gibco	16140-071
FLUOstar OPTIMA plate reader	BMG LABTECH	413-2132
GraphPad Prism Software (9.0.0)	GraphPad Software, LLC	Version 9.0.0
HERAcell 150i CO2 Incubator	Thermo Scientific	50116047
Hitachi S-4700 Field emission scanning electron microscope equipped with energy dispersive X-ray	Hitachi High-Technologies Corporation	S4700 and EDAX TEAM analysis software
ImageJ software	National Institutes of Health	N/A
Immortalized human bronchial epithelial cells	American Type Culture Collection	CRL-9609
Isotemp freezer	Fisher Scientific
Methanol, 99%	Fisher Chemical	67-56-1
Parafilm sealing film	The Lab Depot	HS234526A
Penicillin/Steptomycin	Gibco	15140-122
Sorvall Legend X1R Centrifuge	Thermo Scientific	75004220
Sorvall T 6000B	DU PONT	T6000B
Trypan blue, 0.4% solution in PBS	MP Biomedicals, LLC	1691049
Vacuum Chamber	Belart	999320237
Zinc Nitrate Hexahydrate, 98% extra pure	Acros Organic	101-96-18-9