title: Applying graphene oxide nano-film over a polycarbonate nanoporous membrane to monitor E. coli by infrared spectroscopy.
abstract: Nano-biosensors are excellent monitoring tools for rapid, specific, sensitive, inexpensive, in-field, on-line, and/or real-time detection of pathogens in foods, soil, air, and water samples. A variety of nano-materials (metallic, polymeric, and/or carbon-based) were employed to enhance the efficacy, efficiency, and sensitivity of these nano-biosensors, including graphene-based materials, especially graphene oxide (GO)-based materials. GO bears many oxygen-bearing groups, enabling ligand conjugation at the high density critical for sensitive detection. We have fabricated GO-modified nano-porous polycarbonate track-etched (PCTE) membranes that were conjugated to an Escherichia coli-specific antibody (Ab) and used to detect E. coli. The random distribution of nanopores on the PCTE membrane surface and the bright coating of the GO onto the membrane were confirmed by scanning electron microscope. Anti-E. coli β-gal Abs were conjugated to the GO surface via 1-ethyl-3,3-dimethylaminopropyl carbodiimide hydrochloride-N-hydroxysuccinimide chemistry; antibody coating was confirmed by the presence of a characteristic IR peak near 1600cm(-1). A non-corresponding Ab (anti-Pseudomonas) was used as a negative control under identical conditions. When E. coli interacted anti-E.coli β-gal with Ab-coated GO-nano-biosensor units, we observed a clear shift in the IR peak from 3373.14 to 3315cm(-1); in contrast, we did not observe any shift in IR peaks when the GO unit was coated with the non-corresponding Ab (anti-Pseudomonas). Therefore, the detection of E. coli using the described GO-nano-sensor unit is highly specific, is highly selective and can be applied for real-time monitoring of E. coli with a detection limit between 100μg/mL and 10μg/mL, similar to existing detection systems.
authors.affiliation: Bionanotechnology & Nanobiosensor Research Laboratory, Biophysics Unit, CBSH, G.B. Pant University of Agriculture & Technology, U.S. Nagar, Pantnagar 263145, India. Electronic address: kps_biophysics@yahoo.co.in.
authors.forename: Krishna Pal
authors.initials: KP
authors.lastname: Singh
authors.affiliation: Bionanotechnology & Nanobiosensor Research Laboratory, Biophysics Unit, CBSH, G.B. Pant University of Agriculture & Technology, U.S. Nagar, Pantnagar 263145, India.
authors.forename: Neeraj Singh
authors.initials: NS
authors.lastname: Dhek
authors.affiliation: Bionanotechnology & Nanobiosensor Research Laboratory, Biophysics Unit, CBSH, G.B. Pant University of Agriculture & Technology, U.S. Nagar, Pantnagar 263145, India.
authors.forename: Anuj
authors.initials: A
authors.lastname: Nehra
authors.affiliation: Center of Excellence of Mountain Biology, Uttarakhand Council for Biotechnology, Biotech Bhavan, U.S. Nagar, Haldi 263146, India.
authors.forename: Sweeti
authors.initials: S
authors.lastname: Ahlawat
authors.affiliation: Basic Research Lab, Center for Cancer Research, NCI-Frederick, NIH, P.O Box B, Bldg. 469, Rm. 216A, Frederick, MD 21702-1201, USA.
authors.forename: Anu
authors.initials: A
authors.lastname: Puri
mesh_terms: D004926:Escherichia coli / Q000302:isolation & purification*; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D057230:Limit of Detection; D008567:Membranes, Artificial; D058608:Nanopores; D011076:Polycarboxylate Cement / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008567:Membranes, Artificial; D011076:Polycarboxylate Cement; C005506:polycarbonate; D006046:Gold; D006108:Graphite
keywords: E. coli detection; FT-IR nano-immunosensor; Graphene oxide (GO); Nano-film