Search

Tumor Treating Fields (TTFields) in combination with chemotherapy and/or radiotherapy have been clinically reported to provide prolonged overall survival in glioblastoma patients. Alternating electric fields with frequencies of 100~300 kHz and magnitudes of 1~3 V/cm are shown to suppress the growth of cancer cells via interactions with polar molecules within dividing cells. Since it is difficult to directly measure the electric fields inside the brain, simulation models of the human head provide a useful tool for predicting the electric field distribution. In the present study, a three-dimensional finite element head model consisting of the scalp, the skull, the dura, the cerebrospinal fluid, and the brain was built to study the electric field distribution under various applied potentials and electrode configurations. For simplicity, a direct-current electric field was used in the simulation. The total power dissipation and temperature elevation due to Joule heating in different head tissues were also evaluated. Based on the results, some guidelines are obtained in designing the electrode configuration for personalized glioblastoma electrotherapy. [ABSTRACT FROM AUTHOR]

Carbohydrates present on cell surfaces mediate cell behavior through interactions with other biomolecules. Due to their structural complexity, diversity, and heterogeneity, it is difficult to fully characterize a variety of carbohydrates and their binding partners. As a result, novel technologies for glycomics applications have been developed, including carbohydrate microarrays and label-free detection methods. In this paper, we report using the combination of oligosaccharide microarrays and the label-free oblique-incidence reflectivity difference microscopy for real-time characterization of oligosaccharide-binding proteins. Aminated human milk oligosaccharides were immobilized on epoxy-coated glass substrates as microarrays for reactions with Family 1 of solute-binding proteins fromBifidobacterium longumsubsp.infantis(B. infantis). Binding affinities of these protein–oligosaccharide interactions showed preferences of Family 1 of solute-binding proteins to host glycans, which helps in characterizing the complex process of human milk oligosaccharides foraging byB. infantis. [ABSTRACT FROM PUBLISHER]

Optical biosensors provide a platform for qualitatively and quantitatively analyzing various biomolecular interactions. In addition to advantages such as label-free and high-throughput detection, these devices are also capable of measuring real-time binding curves in response to changes in optical properties of biomolecules. These kinetic data may be fitted to models to extract binding affinities such as association rates, dissociation rates, and equilibrium dissociation constants. In these biosensors, one of the binding pair is usually immobilized on a solid substrate for capturing the other. Due to the nature of these surface-based methods, mass transport effects and immobilization heterogeneity may cause problems when fitting the kinetic curves with the simple one-to-one Langmuir model. Here, real-time binding curves of various antibody–antigen reactions were obtained using an ellipsometry-based biosensor, and the results were fitted to the simple one-to-one model as well as a more sophisticated approach. The results show that the one-to-two model fitted much better to the curves than the one-to-one model. The two-site model may be explained by assuming two immobilization configurations on the surface. In summary, in fitting real-time curves obtained from optical biosensors, more sophisticated models are usually required to take surface-related issues, such as immobilization heterogeneity, and mass transport effects within targets, into account. [ABSTRACT FROM PUBLISHER]

Endogenous electric field is known to play important roles in the wound-healing process, mainly through its effects on protein synthesis and cell migration. Many clinical studies have demonstrated that electrical stimulation (ES) with steady direct currents is beneficial to accelerating wound-healing, even though the underlying mechanisms remain unclear. In the present study, a three-dimensional finite element wound model was built to optimize the electrode configuration in ES. Four layers of the skin, stratum corneum, epidermis, dermis, and subcutis, with defined thickness and electrical properties were modeled. The main goal was to evaluate the distributions of exogenous electric fields delivered with direct current (DC) stimulation using different electrode configurations such as sizes and positions. Based on the results, some guidelines were obtained in designing the electrode configuration for applications of clinical ES. [ABSTRACT FROM AUTHOR]

One key advantage of label-free biosensors involves the monitoring of binding between biomolecules. However, a number of experimental artifacts may lead to complicated real-time curves that do not fit well to a simple Langmuir model. As a result, the quality of the kinetic data must be improved to obtain accurate reaction rates. By carefully designing experiments, collecting the data, and processing the data, issues arising from signal drift, nonspecific binding, mass-transport effect in solution, mass-transport effect on surface, and curve fitting may be avoided or resolved. Using a label-free oblique-incidence reflectivity difference biosensor, key processes required to obtain reliable kinetic data and accurate reaction rates are described. [ABSTRACT FROM AUTHOR]

Human serum is a mixture of various proteins which may interact with drugs. Therefore, it is of interest to investigate the binding kinetics of pharmaceuticals with their corresponding antibodies in serum. In this article, microarrays and a label-free biosensor were used to study these interactions. Microarrays provide a high-throughput platform for characterizing biomolecular interactions, and the label-free oblique-incidence reflectivity difference biosensor avoids the drawbacks of fluorescence-based methods. The experimental results show that the binding affinities between most of the drugs and their antibodies were reduced in human serum because the bulky proteins block the access to or reduce the stability of the reaction complexes. Therefore, one should be mindful when in vitro or in vivo testing the efficiency of potential drugs and their antibodies. [ABSTRACT FROM AUTHOR]

We demonstrate an effective method for generating libraries of encoded compounds for fabricating large compound microarrays on solid supports. This method is based on one-bead, one-compound synthesis and employs a novel trilayer bead-partition scheme that ensures sufficient quantity of synthesized compounds releasable from each bead for compound microarray fabrication in high-throughput protein–ligand discovery assays. [Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®for the following free supplemental resource(s): Full experimental and spectral details.] [ABSTRACT FROM AUTHOR]

Biosensors are important tools in fields of biophysics, biochemistry, and biomedical engineering because they provide a platform for the detection of various analytes. Currently, fluorescence-based detection methods have been routinely used for their high sensitivity and diverse selections of labeling agents. However, tagging extra molecules (such as dyes) on to one of the binding pair might change the intrinsic binding affinity of that reaction. To do away with this drawback, label-free biosensors based on optical techniques have drawn more and more attention recently because they are non invasive to the biomolecules under investigation. This article reviews some modern optical biosensors including surface plasmon resonance, oblique-incidence reflectivity difference, interferometry, resonant cavity, and resonant waveguide grating. Some of these techniques have already been commercialized for biological applications. While surface plasmon resonance is the most sensitive and commonly used method, oblique-incidence reflectivity difference provides comparable sensitivity with additional advantages in throughput as well as compatibility. It is believed that in the future, optical techniques will still lead the way in the development of label-free biosensors for biological applications. [ABSTRACT FROM AUTHOR]

An oblique-incidence reflectivity difference (OI-RD) scanning microscope was developed for label-free detection of the formation and disintegration of micelles upon solid substrates. Micelles are made of polymers with hydrophilic heads in contact with the surrounding solvent and hydrophobic tails in the micelle center. This characteristic makes them very efficient drug carriers. Streptavidin molecules were first printed on glass slides for capturing biotinylated polymers. Micelles were formed when the concentration of polymers was higher than a critical value. The formation of micelles resulted in an increase in the oblique-incidence reflectivity difference signals. As the concentration of polymers decreased below the critical value, micelles were disintegrated, and a corresponding decrease in the oblique-incidence reflectivity difference signals was observed. This microscope was employed for the real-time monitoring of the formation and disintegration of two different micelles. The critical concentration above which micelles were formed was determined to be around 0.0006 mg/mL for micelles made of PEG5KCA8polymers. The results suggest that this microscope would have practical application in testing the efficiency and durability of micellar drug carriers. [ABSTRACT FROM AUTHOR]

A combination of the microarray platform and oblique-incidence reflectivity difference (OI-RD) microscopy was used to study the dependence of kinetic constants of probe-target reactions on the surface density of immobilized targets. Streptavidin-biotin reactions with a very high binding affinity were employed as the study model. Oblique-incidence reflectivity difference microscopy, a label-free and surface-based detection technique, was developed for monitoring real-time binding curves between two interactive biomolecules, enabling the acquisition of kinetic constants such as on-rate, off-rate, and equilibrium dissociation constants. These kinetic constants are important in characterizing biomolecular interactions because in living cells all intercellular and intermolecular reactions are at dynamic rather than at stable equilibrium. The kinetic constant of streptavidin binding to surface-immobilized biotin-bovine serum albumin was demonstrated to be significantly affected by the density of surface bovine serum albumin conjugates, mainly due to mass-transport effects within targets. [ABSTRACT FROM AUTHOR]

In this paper, we report a new method to incorporate 3D scaffold with electrotaxis measurement in the microfluidic device. The electrotactic response of lung cancer cells in the 3D foam scaffolds which resemble the in vivo pulmonary alveoli may give more insight on cellular behaviors in vivo. The 3D scaffold consists of ordered arrays of uniform spherical pores in gelatin. We found that cell morphology in the 3D scaffold was different from that in 2D substrate. Next, we applied a direct current electric field (EF) of 338 mV/mm through the scaffold for the study of cells' migration within. We measured the migration directedness and speed of different lung cancer cell lines, CL1-0, CL1-5, and A549, and compared with those examined in 2D gelatin-coated and bare substrates. The migration direction is the same for all conditions but there are clear differences in cell morphology, directedness, and migration speed under EF. Our results demonstrate cell migration under EF is different in 2D and 3D environments and possibly due to different cell morphology and/or substrate stiffness. [ABSTRACT FROM AUTHOR]

Metastasis contributes to the increased mortality rate of cancer, but the intricate mechanisms remain unclear. Cancer cells from a primary tumor invade nearby tissues and access the lymphatic or circulatory system. If these cells manage to survive and extravasate from the vasculature into distant tissues and ultimately adapt to survive, they will proliferate and facilitate malignant tumor formation. Traditional two-dimensional (2D) cell cultures offer a rapid and convenient method for validating the efficacy of anticancer drugs within a reasonable cost range, but their utility is limited because of tumors' high heterogeneity in vivo and spatial complexities. Three-dimensional (3D) cell cultures that mimic the physiological conditions of cancer cells in vivo have gained considerable interest. In these cultures, cells assemble into spheroids through gravity, magnetic forces, or their low-adhesion to the plates. Although these approaches address some of the limitations of 2D cultures, they often require a considerable amount of time and cost. Therefore, this study aims to enhance the effectiveness of 3D culture techniques by using microfluidic systems to provide a high-throughput and sensitive pipeline for drug screening. Using these systems, we studied the effects of lanthanide elements, which have garnered interest in cancer treatment, on spheroid formation and cell spreading. Our findings suggest that these elements alter the compactness of cell spheroids and decrease cell mobility. [ABSTRACT FROM AUTHOR]

Collective cell migration plays important roles in various physiological processes. To investigate this collective cellular movement, various wound-healing assays have been developed. In these assays, a "wound" is created mechanically, chemically, optically, or electrically out of a cellular monolayer. Most of these assays are subject to drawbacks of run-to-run variations in wound size/shape and damages to cells/substrate. Moreover, in all these assays, cells are cultured in open, static (non-circulating) environments. In this study, we reported a microfluidics-based wound-healing assay by using the trypsin flow-focusing technique. Fibroblasts were first cultured inside this chip to a cellular monolayer. Then three parallel fluidic flows (containing normal medium and trypsin solution) were introduced into the channels, and cells exposed to protease trypsin were enzymatically detached from the surface. Wounds of three different widths were generated, and subsequent wound-healing processes were observed. This assay is capable of creating three or more wounds of different widths for investigating the effects of various physical and chemical stimuli on wound-healing speeds. The effects of shear stresses, wound widths, and β-lapachone (a wound healing-promoting chemical) on wound-healing speeds were studied. It was found that the wound-healing speed (total area healed per unit time) increased with increasing shear stress and wound width, but under a shear stress of 0.174 mPa the linear healing speed (percent area healed per unit time) was independent of the wound width. Also, the addition of β-lapachone up to 0.5 μM did not accelerate wound healing. This microfluidics-based assay can definitely help in understanding the mechanisms of the wound-healing process and developing new wound-healing therapies. [ABSTRACT FROM AUTHOR]

Abstract Due to rapid industrialization and urbanization, the environment is exposed to many chemicals from natural or anthropogenic sources. The contaminants impact eco-system and human health via food chain. Animals, including humans, are likely to accumulate contaminants in their bodies from direct exposure or feeding behavior, resulting in toxicity. Therefore, evaluation of the toxicity of contaminants is an important issue. Metals are highly toxic but the toxicity depends on many factors, including the valance and the complex form of metals, the organic matter level in the environment, the reducing/oxidizing condition of the environment, and etc. Since the level of metal amount does not directly correlate to bioavailability, cell culture is usually used for toxicity evaluation. In this study, a microfluidic chip was developed to evaluate the cell toxicity from exposure to metals, copper and thallium. Compared to traditional cytotoxicity assay using static state culture with tetrazolium reagent, this microfluidic chip can generate various shear stresses by changing geometry of culture areas or flow rate. Enhancement of shear stresses could increase cell sensitivity toward metal exposure. Therefore, this platform provides a more sensitive platform for quantitative analysis of cell toxicity and could be applied to evaluate toxicity from environmental samples. Graphical abstract Unlabelled Image Highlights • A microfluidic chip is developed to detect metal toxicity. • This microfluidic chip can generate 7 concentrations and 3 shear stresses simultaneously and accurately. • This microfluidic chip is more sensitive than traditional cytotoxicity assays in detecting metal toxicity. • Enhancement of shear stresses could increase cytotoxicity upon metal exposure. [ABSTRACT FROM AUTHOR]

Alkali metal halides have long been used as scintillators for applications as sensors and detectors. Usually, a small amount of impurities are added to these inorganic materials to improve their luminescence efficiencies. We investigate the structures and luminescent properties of un-doped sodium iodide (NaI) and cesium-doped NaI (NaI:Cs) films deposited by thermal vacuum evaporation. Instead of using the toxic element thallium (Tl), we introduced cesium dopant into NaI. This is the first study for the NaI:Cs film excited by UV LED's ultraviolet C (273 nm, 4.54 eV). The luminescence spectra show two main peaks at 3.05 and 4.32/3.955 eV (for fused silica/B270 substrate), originating from the intrinsic defects and/or activator excited states and the intrinsic self-trapped excitons (STEs), respectively. In general, both Cs-doping and post-annealing processes enhance the luminescence performance of NaI films. [ABSTRACT FROM AUTHOR]

The wound-healing assay is an easy and economical way to quantify cell migration under diverse stimuli. Traditional assays such as scratch assays and barrier assays are widely and commonly used, but neither of them can represent the complicated condition when a wound occurs. It has been suggested that wound-healing is related to electric fields, which were found to regulate wound re-epithelialization. As a wound occurs, the disruption of epithelial barrier short-circuits the trans-epithelial potential and then a lateral endogenous electric field is created. This field has been proved invitro as an important cue for guiding the migration of fibroblasts, macrophages, and keratinocytes, a phenomenon termed electrotaxis or galvanotaxis. In this paper, we report a microfluidic electrical-stimulated wound-healing chip (ESWHC) integrating electric field with a modified barrier assay. This chip was used to study the migration of fibroblasts under different conditions such as serum, electric field, and wound-healing-promoting drugs. We successfully demonstrate the feasibility of ESWHC to effectively and quantitatively study cell migration during wound-healing process, and therefore this chip could be useful in drug discovery and drug safety tests. [ABSTRACT FROM AUTHOR]

Label-free biosensors provide an important platform for detecting chemical and biological substances without needing extra labeling agents. Unlike surface-based techniques such as surface plasmon resonance (SPR), interference, and ellipsometry, surface-enhanced Raman spectroscopy (SERS) possesses the advantage of monitoring analytes both on surfaces and in solutions. Increasing the SERS enhancement is crucial to preparing high-quality substrates without quickly losing their stability, sensitivity, and repeatability. However, fabrication methods based on wet chemistry, nanoimprint lithography, spark discharge, and laser ablation have drawbacks of waste of time, complicated processes, or nonreproducibility in surface topography. This study reports the preparation of recyclable TiO2/Ag nanoparticle (AgNP) substrates by using simple arc ion plating and direct-current (dc) magnetron sputtering technologies. The deposited anatase-phased TiO2 ensured the photocatalytic degradation of analytes. By measuring the Raman spectra of rhodamine 6G (R6G) in titrated concentrations, a limit of detection (LOD) of 10−8 M and a SERS enhancement factor (EF) of 1.01 × 109 were attained. Self-cleaning was performed via UV irradiation, and recyclability was achieved after at least five cycles of detection and degradation. The proposed TiO2/AgNP substrates have the potential to serve as eco-friendly SERS enhancers for label-free detection of various chemical and biological substances. [ABSTRACT FROM AUTHOR]

A curved D -type optical fiber sensor (OFS) based on surface plasmon resonance (SPR) is proposed. The parameters, such as the curvature of the fiber, the unpolished depth of the fiber core, the thickness of the deposited gold films, and the incident angle of light upon the gold-deposited surface, affect the sensitivity of this curved OFS. Calculation, simulation, and experiments are performed to optimize the sensitivity by choosing suitable parameters. The feasibility of this curved D -type OFS is demonstrated by monitoring the SPR phenomena of ethylene glycol solutions with different refractive indices. This OFS is applicable as a biosensor for label-free, real-time, and in-situ characterization of biomolecular interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study reports a microfluidic chip for generating a shear stress gradient. • A shear stress gradient is generated perpendicular to the medium flow. • NIH3T3 cells do not migrate directionally under a gradient of 0.015 Pa/mm. • CL1-5 cells show preferences for higher shear stress environments. • CL1-5 cells align parallel to the medium flow. Cells respond not only to biological regulatory factors but also to physical stimuli such as electric fields, light, and shear stress in their environment. These stimuli can lead to cell migration and morphological changes. In the human body, cells encounter fluid shear stress induced by interstitial flow, lymphatic flow, blood flow, or organ-specific conditions within their micro-environments. Therefore, fluid shear stress, a classic mechanical force, has gained significant attention in wound healing and cancer metastasis. In this study, a microfluidic chip was developed to both culture cells and generate a shear stress gradient to direct cell migration. The design of this device's geometry allows the generation of a shear stress gradient perpendicular to the direction of medium flow. This greatly eliminates the influence of flow-induced cell responses. Using mouse fibroblast cells (NIH3T3) and human lung cancer cells (CL1-5) as models, their migration directionality, migration rates, and alignment in response to the shear stress gradient were investigated. Within the stress range of 0.095–0.155 Pa and a gradient of 0.015 Pa/mm, NIH3T3 cells did not exhibit significant directional migration, differences in migration rates, or specific alignment patterns. In contrast, CL1-5 cells preferred higher shear stress environments and alignment parallel to the medium flow, suggesting that these conditions could induce higher mobility in these cancer cells. [ABSTRACT FROM AUTHOR]

This study explores the application of metallic silver coatings in optical telescopes. The silver film demonstrates high reflectance across the visible to the infrared spectral range and exhibits excellent adhesion properties. X-ray photoelectron spectroscopy (XPS) analyzes the bonding properties of the two interfaces above and below the silver layer. The main bonds identified in the silver interfaces were Ag–O, Ag–Si, and Ag–Al 2 O 3. The covalent character Ag–O bond is crucial for layer adhesion, as it causes a shift to the high binding energy of Ag0 in the Ag3d XPS spectrum. Enhanced silver multilayers retaining their reflectance and adhesion are essential for space optics in harsh environments. • XPS was employed to analyze the bonding properties between the upper (SAO) and lower (Al 2 O 3) layers of the silver coating. • Covalent character Ag–O bonds at the interface improves adhesion by shifting to a higher binding energy of Ag0. • The proposed silver coating design achieves high adhesion, making it suitable for highly reflective imaging systems. [ABSTRACT FROM AUTHOR]

This study delves into the structural and luminescent properties of un-doped and potassium (K) doped cesium iodide (CsI) thin films fabricated by thermal vacuum co-evaporation. These films were characterized by aspects of X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, energy-dispersive X-ray spectroscopy (EDS), X-ray luminescence spectra, and X-ray photoelectron spectroscopy (XPS). The predominant crystal orientation changed from the (200) plane to the (110) one after K-doping. Upon X-ray excitation, the defect-related luminescence spectra of K-doped CsI films unveiled a broad peak from 380 to 600 nm in the region. Notably, the sample doped with 2 wt% of KI exhibited the highest luminescence efficiency. Finally, XPS analysis disclosed the binding energies associated with Cs–I and multiple-I ions. This observation suggested the existence of crystal defects, including F-, H-, and V k -centers, in addition to the conventional CsI ionic crystal structure. • This study details the fabrication and characterization of potassium (K)-doped CsI films. • These films were characterized mainly by X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS). • The sample doped with 2 wt% of KI exhibited the highest luminescence efficiency. • XPS analysis disclosed the binding energies, suggesting the existence of F-, H-, and Vk-centers. • These results could find applications in the field of X-ray detection. [ABSTRACT FROM AUTHOR]

• Newly developed in vitro stopper assays are performed with two commonly-used surface coatings. • Data of gap width show that gelatin and PLL coatings increase the rate of gap closure. • Data of the number of cells show that the two coatings increase the rate of population growth. • Model calibration shows that the coatings increase cell motility without affecting proliferation. In vitro surface coatings are widely used to mimic the role of extracellular matrix in the in vivo environment. Different effects are reported for different surface coatings, however, some of these results are inconsistent across the literature. To explore the role of different surface coatings, we use a new modified stopper-based wound-healing assay, called a stopper assay , with two commonly used surface coatings: gelatin and poly-L-lysine (PLL). Our experimental data shows the gap width decreases faster with the gelatin and PLL coatings. Similarly, the number of cells in certain subregions increases faster with these coatings. Unfortunately, neither of these observations provides definitive mechanistic insight into the role of the coatings. To provide such insight we calibrate the solution of the Fisher-Kolmogorov model to match the experimental data. Our parameter estimates indicate that both coatings significantly increase cell motility without affecting cell proliferation. [ABSTRACT FROM AUTHOR]

The authors wish to make the following correction to this paper [[1]]. The authors declare no conflicts of interest. 1 Lin J.Y., Lo K.-Y., Sun Y.S. Effects of Substrate-Coating Materials on the Wound-Healing Process. [Extracted from the article]

The wound-healing assay is commonly and widely used for investigating collective cell migration under various physical and chemical stimuli. Substrate-coating materials are shown to affect the wound-healing process in a cell-type dependent manner. However, experiment-to-experiment variations make it difficult to compare results from different assays. In this paper, a modified barrier wound-healing assay was reported for studying the wound-healing process on different substrates in one single petri dish. In short, half of a dish was covered with the tape, and coating materials, poly-l-lysine and gelatin, were applied to the surface. After peeling off the tape, half of the surface was coated with the desired material. Then a customized barrier was placed inside the dish to create the wound. The results indicated that surface coating did not affect cell proliferation/viability, and the wound-healing rate increased in coated surfaces compared to uncoated ones. The present study provides a platform for further understanding the mechanisms of substrate coating-dependent wound-healing processes. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are known to be a key factor in the development of cancer, and many exogenous sources are supposed to be related to the formation of ROS. In this paper, a microfluidic chip was developed for studying the production of ROS in lung cancer cells under different chemical and physical stimuli. This chip has two unique features: (1) five relative concentrations of 0, 1/8, 1/2, 7/8, and 1 are achieved in the culture regions; (2) a shear stress gradient is produced inside each of the five culture areas. Lung cancer cells were seeded inside this biocompatible chip for investigating their response to different concentrations of H2O2, a chemical stimulus known to increase the production of ROS. Then the effect of shear stress, a physical stimulus, on lung cancer cells was examined, showing that the production of ROS was increased in response to a larger shear stress. Finally, two antioxidants, α-tocopherol and ferulic acid, were used to study their effects on reducing ROS. It was found that high-dose α-tocopherol was not able to effectively eliminate the ROS produced inside cells. This counter effect was not observed in cells cultured in a traditional chamber slide, where no shear stress was present. This result suggests that the current microfluidic chip provides an in vitro platform best mimicking the physiological condition where cells are under circulating conditions. [ABSTRACT FROM AUTHOR]

Cell migration is an important process involved in wound healing, tissue development, and so on. Many studies have been conducted to explore how certain chemicals and electric fields induce cell movements in specific directions, which are phenomena termed chemotaxis and electrotaxis, respectively. However, phototaxis, the directional migration of cells or organisms toward or away from light, is rarely investigated due to the difficulty of generating a precise and controllable light gradient. In this study, we designed and fabricated a microfluidic chip for simultaneously culturing cells and generating a blue light gradient for guiding cell migration. A concentration gradient was first established inside this chip, and by illuminating it with a blue light-emitting diode (LED), a blue light gradient was generated underneath. Cell migration in response to this light stimulus was observed. It was found that lung cancer cells migrated to the dark side of the gradient, and the intracellular reactive oxygen species (ROS) was proportional to the intensity of the blue light. [ABSTRACT FROM AUTHOR]