Gargibala Satpathy1,2, Goutam Kumar Chandra3, E Manikandan4,5, D Roy Mahapatra6, Siva Umapathy7,8. 1. Central Research Laboratory, Sree Balaji Medical College & Hospital (SBMCH), Bharath Institute for Higher Education & Research (BIHER), Bharath University, Chennai, Tamil Nadu, 600073, India. 2. Laboratory of Integrative Multiscale Engineering Materials and Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore, 560012, India. 3. Department of Physics, NIT Calicut, Calicut, Kerala, 673601, India. 4. Central Research Laboratory, Sree Balaji Medical College & Hospital (SBMCH), Bharath Institute for Higher Education & Research (BIHER), Bharath University, Chennai, Tamil Nadu, 600073, India. maniphysics@gmail.com. 5. Solid-State Nanoscale Laboratory, Department of Physics, TUCAS Campus, Thiruvalluvar University, Thennangur, Vellore, 604408, India. maniphysics@gmail.com. 6. Laboratory of Integrative Multiscale Engineering Materials and Systems, Department of Aerospace Engineering, Indian Institute of Science, Bangalore, 560012, India. droymahapatra@aero.iisc.ernet.in. 7. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India. siva.umapathy@gmail.com. 8. Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, 462066, India. siva.umapathy@gmail.com.
Abstract
OBJECTIVE: This study aims to detect pathogenic Escherichia coli (E. coli) bacteria using non-destructive fluorescence microscopy and micro-Raman spectroscopy. RESULTS: Raman vibrational spectroscopy provides additional information regarding biochemical changes at the cellular level. We have used two nanomaterials zinc oxide nanoparticles (ZnO-NPs) and gold nanoparticles (Au-NPs) to detect pathogenic E. coli. The scanning electron microscope (SEM) with energy dispersive X-ray (EDAX) spectroscopy exhibit surface morphology and the elemental composition of the synthesized NPs. The metal NPs are useful contrast agents due to the surface plasmon resonance (SPR) to detect the signal intensity and hence the bacterial cells. The changes due to the interaction between cells and NPs are further correlated to the change in the surface charge and stiffness of the cell surface with the help of the fluorescence microscopic assay. CONCLUSIONS: We conclude that when two E. coli strains (MTCC723 and MTCC443) and NPs are respectively mixed and kept overnight, the growth of bacteria are inhibited by ZnO-NPs due to changes in cell membrane permeability and intracellular metabolic system under fluorescence microscopy. However, SPR possessed Au-NPs result in enhanced fluorescence of both pathogens. In addition, with the help of Raman microscopy and element analysis, significant changes are observed when Au-NPs are added with the two strains as compared to ZnO-NPs due to protein, lipid and DNA/RNA induced conformational changes.
OBJECTIVE: This study aims to detect pathogenic Escherichia coli (E. coli) bacteria using non-destructive fluorescence microscopy and micro-Raman spectroscopy. RESULTS: Raman vibrational spectroscopy provides additional information regarding biochemical changes at the cellular level. We have used two nanomaterials zinc oxide nanoparticles (ZnO-NPs) and gold nanoparticles (Au-NPs) to detect pathogenic E. coli. The scanning electron microscope (SEM) with energy dispersive X-ray (EDAX) spectroscopy exhibit surface morphology and the elemental composition of the synthesized NPs. The metal NPs are useful contrast agents due to the surface plasmon resonance (SPR) to detect the signal intensity and hence the bacterial cells. The changes due to the interaction between cells and NPs are further correlated to the change in the surface charge and stiffness of the cell surface with the help of the fluorescence microscopic assay. CONCLUSIONS: We conclude that when two E. coli strains (MTCC723 and MTCC443) and NPs are respectively mixed and kept overnight, the growth of bacteria are inhibited by ZnO-NPs due to changes in cell membrane permeability and intracellular metabolic system under fluorescence microscopy. However, SPR possessed Au-NPs result in enhanced fluorescence of both pathogens. In addition, with the help of Raman microscopy and element analysis, significant changes are observed when Au-NPs are added with the two strains as compared to ZnO-NPs due to protein, lipid and DNA/RNA induced conformational changes.
Entities:
Keywords:
Bacteria; E. coli; Fluorescence spectroscopy; Gold and ZnO nanoparticles; Pathogen; Raman