Detection Of Viscosity Changes Research Articles

Molecular rotor bearing naphthol hydrazone Schiff base for sensing viscosity changes in solutions and biosystems

Viscosity is an important parameter in cells since it is closely related to a few severe human diseases. The development of fluorescent probes that can detect changes in intracellular viscosity has become an effective tool for monitoring the intracellular microenvironment. In this work, an efficient Schiff base molecular rotor, NaForm, is designed and synthesized by covalently linking a naphthol hydrazine derivative with the methyl 4-formylbenzoate group for the optical detection of viscosity changes. By increasing the viscosity of solvents, a significant enhancement of fluorescence for the probe at the yellow-green channel is observed. The probe also exhibits the advantages of high sensitivity and large Stokes shift of 128 nm. Both theoretical calculations and spectroscopic measurements suggest that the inhibition of chemical bond rotation between the hydrazine and the benzene ring leads to such a profound turn-on response. The successful applications of the probe in HeLa cells and zebrafish sufficiently demonstrate the privilege of NaForm as a practical viscosity-dependant chemosensor in aqueous samples and organisms. This chemosensor holds great promise for studying intracellular viscosity effects in various biological contexts.

Fluorescent styrenes for mitochondrial imaging and viscosity sensing.

Fluorophores bearing cationic pendants, such as the pyridinium group, tend to preferentially accumulate in mitochondria, whereas those with pentafluorophenyl groups display a distinct affinity for the endoplasmic reticulum. In this study, we designed fluorophores incorporating pyridinium and pentafluorophenyl pendants and examined their impact on sub-cellular localization. Remarkably, the fluorophores exhibited a notable propensity for the mitochondrial membrane. Furthermore, these fluorophores revealed dual functionality by facilitating the detection of viscosity changes within the sub-cellular environment and serving as heavy-atom-free photosensitizers. With easy chemical tunability, wash-free imaging, and a favorable signal-to-noise ratio, these fluorophores are valuable tools for imaging mitochondria and investigating their cellular processes.

A red-emitting mitochondria targetable fluorescent probe for detecting viscosity in HeLa, zebrafish, and mice.

Viscosity, an essential parameter of the cellular microenvironment, has the ability to indicate the condition of living cells. It is closely linked to numerous diseases like Alzheimer's disease, diabetes, and cardiovascular disorders. Therefore, it is necessary to design tools to effectively monitor viscosity changes, which could provide promising avenues for therapeutic interventions in these diseases. Herein, we report a novel mitochondria-targeting fluorescent probe GX-VS which was suitable for the detection of viscosity changes in vivo and in vitro. The probe GX-VS had many advantages such as long emission wavelength (650 nm), large Stokes shift (105 nm), significant fluorescence enhancement (59-fold), high sensitivity, good biocompatibility and so on. Biological experiments showed that the probe could target mitochondria and detect viscosity alterations in HeLa cells. Moreover, it has been successfully utilized to monitor viscosity changes induced by lipopolysaccharides (LPS) in inflammatory zebrafishes and living mice, which further underscored the capacity of GX-VS to explore fluctuations in viscosity within living organisms.

A novel fluorescence probe for simultaneous detection of mitochondrial viscosity in hepatic ischemia reperfusion injury models.

Acute liver failure caused by hepatic ischemia reperfusion injury (HIRI) poses a severe threat to life, emphasizing the urgent need for precise and timely early diagnosis. Viscosity, a key parameter reflecting active analyte levels at the cellular level, remains underexplored in relation to HIRI. To address this gap, we have developed a groundbreaking near-infrared molecule rotator, PN, exhibiting exceptional characteristics. PN demonstrates remarkable sensitivity, with a 32-fold change in response to viscosity, ranging from PBS to glycerol solution. PN's distinctive features include maximum emission wavelength 790 nm, as well as an impressive Stokes shift 190 nm. Moreover, PN exhibits the ability to sensitively and selectively differentiate nystatin-induced viscosity changes within living cells, and can be used for the detection of viscosity changes in the HIRI mouse model. This capability enhances our understanding of cellular responses, opening avenues for potential applications within disease models. The versatility of PN extends to its potential role in guiding timely monitoring and imaging of viscosity, offering valuable insights into disease progression.

A novel fluorescent probe with large Stokes shift for the detection of viscosity changes and its imaging in living cells.

As an important cellular microenvironmental parameter, viscosity could reflect the status of living cells. Small molecular fluorescent probes are a vital tool to measure the change of viscosity in living cells. A novel fluorescence probe ZL-1 with a large Stokes shift (in methanol it reached to 153 nm and in glycerol it reached to 125 nm) and excellent sensitivity toward viscosity was developed. The sharp enhancement of the emission intensity for the probe ZL-1 from low viscous methanol to high viscous glycerol indicated that the probe ZL-1 could respond to the viscosity variations. Moreover, the probe ZL-1 has been successfully utilized to detect of the viscosity variations in living cells.

Construction of a novel mitochondria-targeted near-infrared (NIR) probe for detection of viscosity changes in cancer cells ferroptosis process

Mitochondria, as an important organelle in cells, play an important role in the production of adenosine triphosphate (ATP) and cell signal transduction, as well as control of the cell cycle and growth. Abnormal viscosity is a pivotal factor for indicating mitochondrial dysfunction. In addition, abnormal changes in mitochondrial viscosity have been confirmed to be closely related to many diseases and malfunctions, such as cell malignancy, atherosclerosis, diabetes, and Alzheimer's disease. Therefore, the development of mitochondrial viscosity response probe and its application in mitochondrial viscosity measurement are considered as a new tool to understand diseases. So far, most of the fluorescent probes used to detect mitochondrial viscosity have emission wavelengths in the visible region, making them less penetrable to tissue. In this work, we report a novel near-infrared fluorescent probe (MN-V) for the detection of mitochondrial viscosity in live cells, which exhibited near infrared emission (795 nm) and high sensitivity towards viscosity changes. The fluorescence intensity of the probe at 795 nm has a 37 times increase from pure PBS solution to glycerol. There was a linear relationship between the fluorescence intensity and the media viscosity. The probe MN-V was applicable to detection of the viscosity changes in living cells and zebrafish. Most importantly, with the probe we found that during cancer cells ferroptosis process was accompanied by an increase in mitochondrial viscosity.

Development of a one-step synthesized red emission fluorescent probe for sensitive detection of viscosity in vitro and in vivo

Diseases caused by metabolic abnormalities, such as inflammation and fatty liver, which are characterized by high viscosity, so it is necessary to detect the change of viscosity in vivo and in vitro. Due to the advantages of high sensitivity, noninvasive detection, high selectivity and real-time imaging, fluorescence imaging has become an effective means to detect biological parameters of biomolecules and life systems. Therefore, we have prepared a red emitting fluorescent probe NBI-V with easy synthesis which can ensure that the probe can be developed for the widely used to detection of viscosity changes in vivo and in vitro. The probe NBI-V has good stability, high response times, selectivity, and good biocompatibility. As the viscosity of a water-glycerol system increased from 1.29 cp to 937.48 cp, the fluorescence of NBI-V was increased by about 77 times. Biological experiments showed that the probe NBI-V can target mitochondria, and the Pearson correlation coefficient was as high as 0.89. What's more, it can distinguish normal liver from fatty liver, and can detect the viscosity changes caused by inflammation in mice.

Real-Time Monitoring Mitochondrial Viscosity during Mitophagy Using a Mitochondria-Immobilized Near-Infrared Aggregation-Induced Emission Probe.

Mitophagy plays a crucial role in maintaining intracellular homeostasis through the removal of dysfunctional mitochondria and recycling their constituents in a lysosome-degradative pathway, which leads to microenvironmental changes within mitochondria, such as the pH, viscosity, and polarity. However, most of the mitochondrial fluorescence viscosity probes only rely on electrostatic attraction and readily leak out from the mitochondria during mitophagy with a decreased membrane potential, thus easily leading to an inaccurate detection of viscosity changes. In this work, we report a mitochondria-immobilized NIR-emissive aggregation-induced emission (AIE) probe CS-Py-BC, which allows for an off-on fluorescence response to viscosity, thus enabling the real-time monitoring viscosity variation during mitophagy. This system consists of a cyanostilbene skeleton as the AIE active core and viscosity-sensitive unit, a pyridinium cation for the mitochondria-targeting group, and a benzyl chloride subunit that induces mitochondrial immobilization. As the viscosity increased from 0.903 cP (0% glycerol) to 965 cP (99% glycerol), CS-Py-BC exhibited an about 92-fold increase in fluorescence intensity at 650 nm, which might be attributed to the restriction of rotation and inhibition of twisted intramolecular charge transfer in a high viscosity system. We also revealed that CS-Py-BC could be well immobilized onto mitochondria, regardless of the mitochondrial membrane potential fluctuation. Most importantly, using CS-Py-BC, we have successfully visualized the increased mitochondrial viscosity during starvation or rapamycin-induced mitophagy in real time. All these features render CS-Py-BC a promising candidate to investigate mitophagy-associated dynamic physiological and pathological processes.

A novel near-infrared probe with large Stokes shift for the detection of viscosity changes in living cells

The status of living cells can be reflected by the changes of intracellular viscosity. Small molecular fluorescent probes are robust tools for measuring viscosity changes in living cells. Therefore, we constructed a near-infrared viscosity sensitive probe ZF1, which had a large Stokes shift, in methanol the Stokes reached to 148 nm and in glycerol it reached to 126 nm in viscous media, a significant enhancement of fluorescence at around 740 nm was observed. The probe ZF1 exhibited an 18.43-fold increasement of fluorescence intensity in glycerol. Moreover, in living cells, the probe ZF1 was applicable to detection of the viscosity changes.

Screening of dicyanoisophorone-based probes for highly sensitive detection of viscosity changes in living cells and zebrafish.

Herein, seven viscosity-sensitive probes were developed via simple structural modification of dicyanoisophorone (DCO)-derived dyes. Among them, DCO-5 significantly enhances (180-fold) the response signal in highly viscous aqueous media while showing insensitivity to polarity changes or pH variations, and enables the successful detection of viscosity changes in nystatin-treated HepG2 cells, PC 12 cells and zebrafish.

Construction of a novel GQD based ratiometric fluorescent composite probe for viscosity detection.

Herein, a novel ratiometric fluorescent composite nanoprobe RV-1@GQDs-OH was developed based on OH-functionalized GQDs (GQDs-OH) and molecular probe (RV-1) viaπ-π stacking. Compared with the conventional "on-off" viscosity probes, RV-1@GQDs-OH can be successfully applied in living systems for the ratiometric detection of viscosity changes in the viscosity range of 0-600 cP.

A highly sensitive red-emitting probe for the detection of viscosity changes in living cells, zebrafish, and human blood samples.

Intracellular viscosity can be measured to reflect the state of living cells. Fluorescent probes are powerful tools for viscosity detection in vivo. Herein, we report on a novel red-emitting viscosity-sensitive probe DJH with a large Stokes shift of 165 nm, showing a 400-fold fluorescence enhancement from PBS solution to 90% glycerol. The probe was suitable for the visualization of the changes in viscosity within living cells and also in zebrafish treated with microplastics for the first time. Furthermore, the viscosity of fresh blood from diabetic mice and hypertensive and diabetic patients was first evaluated by using DJH. These results showed that the probe has a wide range of potential applications in basic research on environmental pollution and in the pre-diagnosis of patients.

A novel mitochondria-targeted near-infrared (NIR) probe for detection of viscosity changes in living cell, zebra fishes and living mice

Viscosity is a key factor that determines the diffusion-controlled processes in biological systems. The matrix of mitochondria contains various enzymes and other proteins with high density, and the diffusion of which are severely restricted by the cristae, making it the most crowded place in the cells. Herein, we reported a new near-infrared probe NV-1 with increased Stokes shift for monitoring viscosity changes in mitochondria. A remarkable increase of the fluorescence was observed in glycerol compared with which was observed in methanol at 744 nm. The probe was applied for measuring viscosity changes not only in mitochondria, but also in vivo (in zebra fishes and mice).

Development of a Portable Dielectric Biosensor for Rapid Detection of Viscosity Variations and Its In Vitro Evaluations Using Saliva Samples of COPD Patients and Healthy Control.

Chronic Obstructive Pulmonary Disease (COPD) is a life-threatening lung disease affecting millions of people worldwide. Although the majority of patients with objective COPD go undiagnosed until the late stages of their disease, recent studies suggest that the regular screening of sputum viscosity could provide important information on the disease detection. Since the viscosity of sputum is mainly defined by its mucin–protein and water contents, dielectric biosensors can be used for detection of viscosity variations by screening changes in sputum’s contents. Therefore, the objective of this work was to develop a portable dielectric biosensor for rapid detection of viscosity changes and to evaluate its clinical performance in characterizing viscosity differences of saliva samples collected from COPD patients and Healthy Control (HC). For this purpose, a portable dielectric biosensor, capable of providing real-time measurements, was developed. The sensor performance for dielectric characterization of mediums with high water content, such as saliva, was evaluated using isopropanol–water mixtures. Subsequently, saliva samples, collected from COPD patients and HC, were investigated for clinical assessments. The radio frequency biosensor provided high repeatability of 1.1% throughout experiments. High repeatability, ease of cleaning, low-cost, and portability of the biosensor made it a suitable technology for point-of-care applications.

A novel mitochondria-targeted rhodamine analogue for the detection of viscosity changes in living cells, zebra fish and living mice.

Monitoring the intracellular viscosity changes is crucial for better understanding diffusion-controlled cellular processes. Herein, we synthesized a novel phenyl-substituted imidazole-fused rhodamine analogue RV-1 with a long absorption wavelength at 573 nm and a large Stokes shift of about 82 nm for monitoring the changes in cellular viscosity. The new probe RV-1 showed a very strong fluorescence emission at around 655 nm, with a 48.5-fold enhancement of fluorescence intensity from methanol to 99% glycerol. Significantly, the innovative probe RV-1 was successfully applied for the detection of viscosity changes not only in living cells, but also in zebra fish and living mice.

A MEMS affinity glucose sensor using a biocompatible glucose-responsive polymer

We present a MEMS affinity sensor that can potentially allow long-term continuous monitoring of glucose in subcutaneous tissue for diabetes management. The sensing principle is based on detection of viscosity changes due to affinity binding between glucose and poly(acrylamide- ran-3-acrylamidophenylboronic acid) (PAA- ran-PAAPBA), a biocompatible, glucose-specific polymer. The device uses a magnetically driven vibrating microcantilever as a sensing element, which is fabricated from Parylene and situated in a microchamber. A solution of PAA- ran-PAAPBA fills the microchamber, which is separated from the surroundings by a semi-permeable membrane. Glucose permeates through the membrane and binds reversibly to the phenylboronic acid moiety of the polymer. This results in a viscosity change of the sensing solution, which is obtained by measuring the damped cantilever vibration using an optical lever setup, allowing determination of the glucose concentration. Experimental results demonstrate that the device is capable of detecting glucose at physiologically relevant concentrations from 27 mg/dL to 324 mg/dL. The glucose response time constant of the sensor is approximately 3 min, which can be further improved with device design optimization. Excellent reversibility and stability are observed in sensor responses, as highly desired for long-term, stable continuous glucose monitoring.