scholarly journals Immobilization of Thermoalkalophilic Esterase Onto Magnetic-Cornstarch Nanoparticle

2021 ◽  
Author(s):  
Yasin Öz ◽  
Yusuf Sürmeli ◽  
Gulsah Sanli-Mohamed
Keyword(s):  
Magnetic Particles ◽  
Residual Activity ◽  
Entrapment Efficiency ◽  
Surface Enhanced Raman Spectroscopy ◽  
Maximum Activity ◽  
Similar Morphology ◽  
Molar Ratios ◽  
Enzyme Recovery ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Abstract The immobilization of the biocatalysts onto magnetic nanoparticles (MNPs) has been extensively applied since the external magnetic field facilitates the enzyme recovery from the reaction mixture. In the present study, glutaraldehyde-modified magnetite-cornstarch nanoparticles (MCNs) were successfully synthesized, elaborately characterized by ZetaSizer and surface-enhanced raman spectroscopy (SERS), and used for the immobilization of a thermoalkalophilic esterase from Geobacillus sp. The optimal immobilization conditions were obtained at 65oC, 2:3 molar ratios of Fe2+:Fe3+ and 1 g cornstarch resulted in approximately 90 nm magnetic particles in size. Also, immobilization yield and entrapment efficiency of the esterase were found as 74% and 82%, respectively. Scanning Electron Microscopy (SEM) micrographs showed that MCNs were uniform, spherical in shape, and well dispersed and esterase immobilized MCNs displayed similar morphology as free MCNs. The maximum activity of free and immobilized esterase was obtained at 80oC and pH 9. Immobilization onto glutaraldehyde-modified MCNs significantly enhanced the esterase thermostability. Additionally, the immobilized esterase kept its residual activity of 75% after three sequential cycles, suggesting that it has favorable operational stability.

Bacterial detection and differentiation via direct volatile organic compound sensing with surface enhanced Raman spectroscopy

2017 ◽  
Author(s):  
Caitlin S. DeJong ◽  
David I. Wang ◽  
Aleksandr Polyakov ◽  
Anita Rogacs ◽  
Steven J. Simske ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bacterial Infections ◽  
Direct Detection ◽  
Point Of Care ◽  
Surface Enhanced Raman Spectroscopy ◽  
E Coli ◽  
Recent Emergence ◽  
Surface Enhanced ◽  
Volatile Organic ◽  
Surface Enhanced Raman

Through the direct detection of bacterial volatile organic compounds (VOCs), via surface enhanced Raman spectroscopy (SERS), we report here a reconfigurable assay for the identification and monitoring of bacteria. We demonstrate differentiation between highly clinically relevant organisms: <i>Escherichia coli</i>, <i>Enterobacter cloacae</i>, and <i>Serratia marcescens</i>. This is the first differentiation of bacteria via SERS of bacterial VOC signatures. The assay also detected as few as 10 CFU/ml of <i>E. coli</i> in under 12 hrs, and detected <i>E. coli</i> from whole human blood and human urine in 16 hrs at clinically relevant concentrations of 10<sup>3</sup> CFU/ml and 10<sup>4</sup> CFU/ml, respectively. In addition, the recent emergence of portable Raman spectrometers uniquely allows SERS to bring VOC detection to point-of-care settings for diagnosing bacterial infections.

scholarly journals Imaging and SERS Study of the Au Nanoparticles Interaction with HPV and Carcinogenic Cervical Tissues

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3758
Author(s):  
Andrea Ceja-Fdez ◽  
Ramon Carriles ◽  
Ana Lilia González-Yebra ◽  
Juan Vivero-Escoto ◽  
Elder de la Rosa ◽  
...  
Keyword(s):  
Multiphoton Microscopy ◽  
Surface Enhanced Raman Spectroscopy ◽  
Rapid Screening ◽  
Emission Region ◽  
Sem Images ◽  
Spectral Signatures ◽  
Two Photon ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Gold Nps

In this work, gold NPs were prepared by the Turkevich method, and their interaction with HPV and cancerous cervical tissues were studied by scanning electron microscopy, energy-dispersive x-ray spectroscopy, confocal and multiphoton microscopy and SERS. The SEM images confirmed the presence and localization of the gold NPs inside of the two kinds of tissues. The light absorption of the gold NPs was at 520 nm. However, it was possible to obtain two-photon imaging (red emission region) of the gold NPs inside of the tissue, exciting the samples at 900 nm, observing the morphology of the tissues. The infrared absorption was probably due to the aggregation of gold NPs inside the tissues. Therefore, through the interaction of gold nanoparticles with the HPV and cancerous cervical tissues, a surface enhanced Raman spectroscopy (SERS) was obtained. As preliminary studies, having an average of 1000 Raman spectra per tissue, SERS signals showed changes between the HPV-infected and the carcinogenic tissues; these spectral signatures occurred mainly in the DNA bands, potentially offering a tool for the rapid screening of cancer.

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