Synthesis of gold nanocluster-loaded lysozyme nanoparticles for label-free ratiometric fluorescent pH sensing: applications to enzyme–substrate systems and cellular imaging

2019 ◽  
Vol 7 (24) ◽  
pp. 3876-3883 ◽  
Author(s):  
Shanmugam Chandirasekar ◽  
Jyun-Guo You ◽  
Jhe-Hong Xue ◽  
Wei-Lung Tseng
Keyword(s):  
Cellular Imaging ◽  
Live Cells ◽  
Ph Sensing ◽  
Label Free ◽  
Gold Nanocluster ◽  
Dual Emission ◽  
Ph Changes ◽  
Ratiometric Sensing ◽  
Sensing Applications ◽  
Enzyme Substrate

We have demonstrated the synthesis of gold nanocluster-loaded lysozyme nanoparticles as a dual-emission probe for ratiometric sensing of pH changes in enzyme–substrate systems and live cells.

Naked oats-derived dual-emission carbon nanodots for ratiometric sensing and cellular imaging

2015 ◽  
Vol 210 ◽  
pp. 533-541 ◽  
Author(s):  
Lihong Shi ◽  
Xiaofeng Li ◽  
Yanyan Li ◽  
Xiangping Wen ◽  
Junfen Li ◽  
...  
Keyword(s):  
Cellular Imaging ◽  
Carbon Nanodots ◽  
Dual Emission ◽  
Ratiometric Sensing ◽  
Naked Oats

scholarly journals Covalent and non-covalent coupling of a Au102 nanocluster with a fluorophore: energy transfer, quenching and intracellular pH sensing

2021 ◽  
Author(s):  
Eero Hulkko ◽  
Tanja Lahtinen ◽  
Varpu Marjomäki ◽  
Emmi Pohjolainen ◽  
Ville Saarnio ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Intracellular Ph ◽  
Fluorescent Dye ◽  
Live Cells ◽  
Ph Sensing ◽  
Gold Nanocluster ◽  
Covalent Coupling ◽  
Covalently Bound

A covalently bound hybrid between an atomically precise gold nanocluster and a fluorescent dye is loaded into cells via endocytosis. Acidification of the endosomes activates fluorescence, enabling optical pH sensing inside live cells.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

scholarly journals Utilizing Stimulated Raman Scattering Microscopy To Study Intracellular Distribution of Label-Free Ponatinib in Live Cells

2019 ◽  
Vol 63 (5) ◽  
pp. 2028-2034 ◽  
Author(s):  
Kristel Sepp ◽  
Martin Lee ◽  
Marie T. J. Bluntzer ◽  
G. Vignir Helgason ◽  
Alison N. Hulme ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Intracellular Distribution ◽  
Live Cells ◽  
Label Free ◽  
Stimulated Raman

scholarly journals Utilising Commercially Fabricated Printed Circuit Boards as an Electrochemical Biosensing Platform

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 793
Author(s):  
Uroš Zupančič ◽  
Joshua Rainbow ◽  
Pedro Estrela ◽  
Despina Moschou
Keyword(s):  
Printed Circuit Boards ◽  
Electrochemical Sensors ◽  
Cost Effective ◽  
Electrochemical Sensing ◽  
Label Free ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Sensing Applications ◽  
Electrochemical Biosensing ◽  
Pre Treatment

Printed circuit boards (PCBs) offer a promising platform for the development of electronics-assisted biomedical diagnostic sensors and microsystems. The long-standing industrial basis offers distinctive advantages for cost-effective, reproducible, and easily integrated sample-in-answer-out diagnostic microsystems. Nonetheless, the commercial techniques used in the fabrication of PCBs produce various contaminants potentially degrading severely their stability and repeatability in electrochemical sensing applications. Herein, we analyse for the first time such critical technological considerations, allowing the exploitation of commercial PCB platforms as reliable electrochemical sensing platforms. The presented electrochemical and physical characterisation data reveal clear evidence of both organic and inorganic sensing electrode surface contaminants, which can be removed using various pre-cleaning techniques. We demonstrate that, following such pre-treatment rules, PCB-based electrodes can be reliably fabricated for sensitive electrochemical biosensors. Herein, we demonstrate the applicability of the methodology both for labelled protein (procalcitonin) and label-free nucleic acid (E. coli-specific DNA) biomarker quantification, with observed limits of detection (LoD) of 2 pM and 110 pM, respectively. The proposed optimisation of surface pre-treatment is critical in the development of robust and sensitive PCB-based electrochemical sensors for both clinical and environmental diagnostics and monitoring applications.

scholarly journals Microfluidic Tools for Enhanced Characterization of Therapeutic Stem Cells and Prediction of Their Potential Antimicrobial Secretome

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 750
Author(s):  
Pasquale Marrazzo ◽  
Valeria Pizzuti ◽  
Silvia Zia ◽  
Azzurra Sargenti ◽  
Daniele Gazzola ◽  
...  
Keyword(s):  
Stem Cells ◽  
Defense Mechanisms ◽  
Live Cells ◽  
Label Free ◽  
Bacterial Diseases ◽  
Prospective Application ◽  
Therapy Strategies ◽  
Stromal Stem Cells ◽  
Different Sources

Antibiotic resistance is creating enormous attention on the development of new antibiotic-free therapy strategies for bacterial diseases. Mesenchymal stromal stem cells (MSCs) are the most promising candidates in current clinical trials and included in several cell-therapy protocols. Together with the well-known immunomodulatory and regenerative potential of the MSC secretome, these cells have shown direct and indirect anti-bacterial effects. However, the low reproducibility and standardization of MSCs from different sources are the current limitations prior to the purification of cell-free secreted antimicrobial peptides and exosomes. In order to improve MSC characterization, novel label-free functional tests, evaluating the biophysical properties of the cells, will be advantageous for their cell profiling, population sorting, and quality control. We discuss the potential of emerging microfluidic technologies providing new insights into density, shape, and size of live cells, starting from heterogeneous or 3D cultured samples. The prospective application of these technologies to studying MSC populations may contribute to developing new biopharmaceutical strategies with a view to naturally overcoming bacterial defense mechanisms.

scholarly journals Perfect Absorption and Refractive-Index Sensing by Metasurfaces Composed of Cross-Shaped Hole Arrays in Metal Substrate

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Zhendong Yan ◽  
Chaojun Tang ◽  
Guohua Wu ◽  
Yumei Tang ◽  
Ping Gu ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Performance ◽  
Narrow Band ◽  
Label Free ◽  
Hybrid Mode ◽  
Perfect Absorption ◽  
Refractive Index Sensing ◽  
Sensing Applications ◽  
Silver Substrate ◽  
Hole Arrays

Achieving perfect electromagnetic wave absorption with a sub-nanometer bandwidth is challenging, which, however, is desired for high-performance refractive-index sensing. In this work, we theoretically study metasurfaces for sensing applications based on an ultra-narrow band perfect absorption in the infrared region, whose full width at half maximum (FWHM) is only 1.74 nm. The studied metasurfaces are composed of a periodic array of cross-shaped holes in a silver substrate. The ultra-narrow band perfect absorption is related to a hybrid mode, whose physical mechanism is revealed by using a coupling model of two oscillators. The hybrid mode results from the strong coupling between the magnetic resonances in individual cross-shaped holes and the surface plasmon polaritons on the top surface of the silver substrate. Two conventional parameters, sensitivity (S) and figure of merit (FOM), are used to estimate the sensing performance, which are 1317 nm/RIU and 756, respectively. Such high-performance parameters suggest great potential for the application of label-free biosensing.

A label-free aptasensor based on a dual-emission fluorescent strategy for aflatoxin B1 detection

2021 ◽  
pp. 130561
Author(s):  
Yao-Yao Fan ◽  
Jun Li ◽  
Li Fan ◽  
Jie Wen ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Aflatoxin B1 ◽  
Label Free ◽  
Dual Emission
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