Gold-Photodeposited Silver Nanowire Endoscopy for Cytosolic and Nuclear pH Sensing

Abstract

Intracellular pH variations are a crucial indicator of physiological and pathological conditions. As such, cancer is known to have a direct interplay with pH dysregulation. For investigation of the pH alterations in cells, metal nanoparticles have been widely used as surface-enhanced Raman scattering (SERS)-based sensors thanks to their high pH sensitivity. However, these SERS probes allow for detection of the pH exclusively at the acidic compartments of the cells (endolysosomes), where particles are entrapped after their endocytosis. Consequently, the results obtained with metal nanoparticles are limited, and the relationship between the pH values detected in the cells and their physiological conditions remains unclear. Herein, we propose an alternative approach based on gold-deposited silver nanowire endoscopy to study cytosolic and nuclear pH variations with high spatiotemporal resolution and sensitivity. The sensing probe was fabricated by depositing gold nanostructures on silver nanowires (Au-dep AgNWs) via visible-laser-light irradiation and modifying the surface with a pH-responsive Raman reporter (4-mercaptobenzoic acid). The high pH sensitivity was demonstrated by immersing the probe in solutions with different pH values (4.4−9.3). The endoscopic probe was then inserted into either the nucleus or cytosol of a living HeLa cell for site-specific pH sensing. The same experiments were performed after the addition of a hypoxia mimetic agent (CoCl 2 ) and an anticancer drug (cisplatin), individually. Notably, our probe accurately detected specific pH variations upon these treatments over time. Similar pH alterations were not measured in untreated cells. The results reported in this work clearly show that Au-dep AgNW endoscopy is a promising powerful tool for pH-sensing applications in biological systems.

Surface-Roughened SERS-Active Single Silver Nanowire for Simultaneous Detection of Intracellular and Extracellular pHs

“…In contrast, pH e increased by 0.2 pH units during the first 1 h, which then gradually decreased to 6.4 after 12 h. The changes in pH i observed in our experiments, including a small increase between 1 and 3 h of incubation, are consistent with a previous report . The transient pH i increases between 1 and 3 h of incubation might result from the ability of cells to maintain pH homeostasis under cisplatin exposure . Nonetheless, the cause of intracellular acidification still needs further investigation.…”

“…34 The transient pH i increases between 1 and 3 h of incubation might result from the ability of cells to maintain pH homeostasis under cisplatin exposure. 35 Nonetheless, the cause of intracellular acidification still needs further investigation. One possible pathway might be related to the inhibition of NHE1, which regulates pH i by mediating an exchange of intracellular H + and extracellular Na + .…”

DNA-Functionalized Silver Nanoparticles in an Alcoholic Solvent for Environment-Dictated Multimodal Actuation

“…Actuation of the plasmonic nanoparticles by physiological pH also has important applications in detection, information storage, and therapeutics. , Therefore, we next became interested in whether dsDNA-AgNPs can be actuated by charge dissociation/association through pH control. The p K a value of PAA is 4.5 .…”

Site-Specific Synthesis of Conductive Graphitic Nanomaterials on a NiFe Thin Film by Localized Laser Irradiation

“…Those carbon materials are dissolved in and deposited on the metal catalyst, resulting in the selective synthesis of conductive graphitic nanomaterials at the positions of laser-irradiated spots on the NiFe surface. Recently, various laser-induced selective material synthesis methods have been proposed since instant and precise control of laser irradiation conditions enables not only nanoscale localization of material synthesis but also precise control over the material synthesis conditions. − By precisely controlling the laser irradiation conditions (laser power, irradiation time, number of irradiation bursts, etc. ), we demonstrate that conductive graphitic nanomaterials can be selectively synthesized by local laser heating of a NiFe alloy thin film coated on a glass substrate immersed in an ethanol solution.…”