Label-free fiber nanograting sensor for real-time in situ early monitoring of cellular apoptosis

Abstract

The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions. Here, a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells. Because of its nanoscale dimensions, mechanical flexibility, and minimal cytotoxicity to cells, the sensing module can be loaded in cells for long term in situ tracking with high sensitivity. A gradual increase in the nuclear refractive index during the apoptosis process is observed, revealing the increase in molecular density and the decrease in cell volume. The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.

Demonstration of a ZnO-Nanowire-Based Nanograting Temperature Sensor

“…The experimental section demonstrates a ZnOnanograting sensor as a tiny sensor. The fabrication process of tapered optical fiber tip integrated ZnO-Nanograting sensor has three steps [29] [Fig. 3(a)].…”

“…Standard silica fiber [18][19][20], photonic crystal fiber [21,22], and fibers with well-designed structures [23][24][25] based systems are widely invented. Among them, fiber-grating-based sensors [3,11,16,18,[26][27][28][29] are popularly used in engineering applications benefiting from their high sensitivity and stable performance. Conventional fiber gratings are fabricated by phase-mask-assisted ultraviolet (UV) light writing to modulate periodical change of refractive index.…”

“…However, the weak evanescent field, small index modulation, and large size restrict applications in micro-and nano-environment. With the development of the micro-machining techniques, optical fiber-based micro-devices, for example, taper [26,27,30] and nanowire-based [29] sensors fabricated by focused ion beam (FIB) or femtosecond laser methods show a new way. Kou et al [26][27][28]30] developed miniaturized Fabry-Perot cavity and nanogratings on optical fiber taper tip for sensing applications.…”

Label-Free Imaging of Cell Apoptosis by a Light-Addressable Electrochemical Sensor

“…In light of the above concerns, label-free technologies that allow timely single-cell analysis are highly in demand for an insightful investigation of cellular activities. , For example, spontaneous Raman microscopy was reported for mapping dynamic changes in cytochrome c released from mitochondria, which is a highly specific event in apoptotic signaling . Plasmonic-based electrochemical impedance microscopy (P-EIM) has been used to investigate apoptosis processes and intracellular calcium signaling with high spatial and temporal resolution.…”

Development of nano- and microdevices for the next generation of biotechnology, wearables and miniaturized instrumentation

“…This knowledge construction made it possible to discuss in particular the detection of low-level concentrations such as single molecule detection (SMD), 25 biomolecules, biostructures, and other applications such as drug and light delivery, and opto-stimulation 26 ( Fig. 2 ).…”