Risk Factors for Post-Colorectal Endoscopic Submucosal Dissection Bleeding and Efficacy of Carbazochrome Sodium Sulfonate: A Multicenter Retrospective Cohort Study.

INTRODUCTION: Carbazochrome sodium sulfonate (CSS) is a hemostatic agent that reduces capillary permeability and enhances capillary resistance. However, its specific effects on colorectal endoscopic submucosal dissection (ESD) outcomes remain uncertain. This study aimed to assess the risk factors for post-ESD bleeding and the effect of CSS on colorectal ESD outcomes. METHODS: First, we retrospectively analyzed the risk factors for post-ESD bleeding using data from 1,315 lesions in 1,223 patients who underwent ESD for superficial colorectal neoplasms at eight institutions. Second, patients were divided into CSS and non-CSS groups using propensity score matching, and their outcomes from colorectal ESD were analyzed. RESULTS: The risk factors for post-colorectal ESD bleeding were identified as age of ≥70 years, tumor located in the rectum, tumor size of ≥40 mm, and post-ESD defect unclosure in both univariate and multivariate analyses. The CSS and non-CSS groups each consisted of 423 lesions after propensity score matching. The post-colorectal ESD bleeding rate was 3.5% (15/423) and 3.3% (14/423) in the CSS and non-CSS groups, respectively, indicating no significant differences. Among patients with the high-risk factors for post-ESD bleeding, the administration of CSS also did not demonstrate a significant reduction in the post-ESD bleeding rate compared to the non-CSS group. CONCLUSION: CSS administration is ineffective in preventing post-colorectal ESD bleeding in both the general population and individuals at a high risk for such bleeding. Our results indicate the necessity to reconsider the application of CSS for preventing post-colorectal ESD bleeding.

Carbazochrome sodium sulfonate is not effective for prevention of post-gastric endoscopic submucosal dissection bleeding: A retrospective study.

BACKGROUND: Carbazochrome sodium sulfonate (CSS) is conventionally administered to prevent post-endoscopic submucosal dissection (ESD) bleeding in many institutions, but research on its preventive efficacy is lacking. Therefore, we investigated the risk of post-ESD bleeding and the preventive efficacy of CSS administration. METHODS: We retrospectively reviewed 304 lesions in 259 patients with gastric neoplasms who underwent ESD at Asahikawa Medical University Hospital from 2014 to 2021. In the CSS group, CSS 100 mg/day was intravenously infused with maintenance fluid replacement on postoperative days 0-2. The risk factors of post-ESD bleeding, including CSS administration, were investigated. RESULTS: The overall rate of post-ESD bleeding was 4.6% (14/304). The univariate analysis showed that atrial fibrillation (Af), warfarin intake, heparin replacement, and tumor location in the lower third were significant risk factors for increasing the likelihood of postoperative bleeding. In the multivariate analysis, Af (odds ratio [OR] 3.83, 95% CI 1.02-14.30; p < 0.05), heparin replacement (OR 4.60, 95% CI 1.02-20.70; p < 0.05), and tumor location in the lower third of the stomach (OR 6.67, 95% CI 1.43-31.00; p < 0.05) were independent factors for post-ESD bleeding. Post-ESD bleeding was observed in 5.2% (9/174) of the CSS group and 3.8% (5/130) of the non-CSS group, with no significant difference between the two groups (p = 0.783). Additionally, CSS was not shown to have preventive effects in groups with higher-risk factors, such as Af diagnosis, warfarin use, heparin replacement, and tumor location in the lower third of the stomach. CONCLUSION: CSS administration was not effective for the prevention of the post-ESD bleeding in the overall patient population as well as in higher-risk patients. This suggests that the administration of CSS for post-ESD bleeding prevention may need to be reconsidered.

Effects of carbazochrome sodium sulfonate combined with tranexamic acid on hemostasis and inflammation during perioperative period of total hip arthroplasty: A randomized controlled trial.

BACKGROUND: The hemostatic effect of tranexamic acid (TXA) combined with carbazochrome sodium sulfonate (CSS) in total hip arthroplasty (THA) has not been determined. Therefore we performed a randomized study aiming to evaluate the effects of CSS combined with TXA on perioperative blood loss and inflammatory response of THA. HYPOTHESIS: CSS combined with TXA can effectively reduce perioperative blood loss and immune response compared to TXA. MATERIAL AND METHODS: This randomized placebo-controlled trial assigned 150 patients undergoing unilateral primary total hip arthroplasty who underwent direct anterior approach surgery to 3 groups: group A received TXA plus topical CSS; group B received TXA only; and group C received placebo. The main outcome was total blood loss. Secondary outcomes included reduction in hemoglobin concentration, coagulation parameters, inflammatory marker levels, perioperative visual analog scale (VAS) pain score, transfusion rates, postoperative hospital stay, and incidence of thromboembolic events. RESULTS: Total blood loss in group A (668.84±230.95ml) was lower than in group B (940.96±359.22ml) and C (1166.52±342.85ml, p<0.05). We also found that compared with group B, postoperative hip pain, biomarker level of inflammation, visual analogue score (VAS) pain score in group A were significantly improved. The transfusion rate and unit of group A were significantly lower than group C (8 patients; 17.5 units), but there was no statistical difference between group A (no transfusion) and group B (2 patients; 4 units). No differences were observed in thromboembolic and other outcomes among the groups. DISCUSSION: The combined application of topic CSS and TXA is more effective than TXA alone following THA in regard of reducing total blood loss. In addition, CSS combined with TXA is better than TXA alone in terms of improving postoperative hip pain and reducing the level of inflammatory factors. LEVEL OF EVIDENCE: I; randomized controlled study.

Carbazochrome carbon nanotube as drug delivery nanocarrier for anti-bleeding drug: quantum chemical study.

The interaction between drugs and single-walled carbon nanotubes is proving to be of fundamental interest for drug system of delivery and nano-bio-sensing. In this study, the interaction of pristine CNT with carbazochrome, an anti-hemorrhagic or hemostatic agent, was investigated with M06-2X functional and 6-31G* basis set. All probable positions of related adsorption for these kind drugs were thought-out to find out which one is energetically suitable. Based on the achieved data, the stronger interactions appeared the oxygen atom of C = O group and nitrogen atom of imine groups. The topology analysis of QTAIM (quantum theory of atoms in a molecule) method was accomplished to understand the properties of interactions between the CNT and carbazochrome. Frontier molecular orbital energies of all systems, global index including stiffness, softness, chemical Gibbs energies, and electrophilicity parameters, as well as some other important physical data such as dipole moment, polarizability, anisotropy polarisibility, and hyperpolaribility were calculated, evaluated, and then compared together. The essence of the formed bonding model progress along the reaction roots was further validated using electron localization function (ELF) calculations. The highest values of adsorption energies were determined in the range of 18.24 up to 22.12 kcal mol-1 for these kind systems. The acceptable recovery time of 849 s was obtained for the desorption of carbazochrome from the CNT surface under UV-light. The final results exhibit that carbazochrome can serve as a promising carrier and also as sensitive sensors in any kind of practical application.

Varied thyroid disrupting effects of perfluorooctanoic acid (PFOA) and its novel alternatives hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA) in vitro.

Due to its potential adverse effects on human health, perfluorooctanoic acid (PFOA), one of the once widely used legacy per- and polyfluoroalkyl substances (PFASs), has been recently replaced by its novel alternatives including hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA). These alternative PFASs are detected in water and exposed workers. PFASs can enter organs like thyroids, however, it is yet unknown whether the new alternatives are safer than PFOA. In the current study, we compared the thyroid disrupting effects of PFOA and its alternatives GenX and ADONA in vitro with both rat thyroid cell line FRTL5 and primary normal human thyroid (NHT) cells. Cells were exposed to ascendant doses of PFOA, GenX or ADONA for various incubation time and cell viability was assessed by WST-1 assay and LDH assay. The proliferation rate of survived cells was determined by crystal violet-based cell proliferation assay and MTT assay. The gene expression of thyroid hormone regulation-related genes in thyroid cells after exposure was quantified by RT-PCR and Western blot. Our data showed that both PFOA and GenX reduced thyroid cell viability in both dose and time dependent manner, with GenX being more toxic than PFOA at the same condition. Similarly, the proliferation rate of cells survived exposure to PFOA and GenX was considerably impaired, with GenX showing more profound adverse effect than PFOA. Unlike PFOA and GenX, ADONA showed no apparent adverse effects on the viability and proliferation of both thyroid cell types. Gene expression data revealed that all three PFASs altered gene expression in both thyroid cells and the altered gene expression seemed to be PFAS and cell type dependent. Taken together, our data reveal that the thyroid disrupting effects is increased in the order of GenX > PFOA > ADONA. Our findings will be beneficial for the guidance of the future usage of PFASs and development of better alternatives.

Correction pen as a hydrophobic/lipophobic barrier plotter integrated with paper-based chips and a mini UV-torch to implement all-in-one device for determination of carbazochrome.

The design of a cheap, simple, and handy sensing system for rapid quantitation of pharmaceuticals becomes mandatory to ease drug development procedures, quality control, health care, etc. This work describes a simple, innovative, and easily manufactured paper-based device using a correction pen as a plotter for hydrophobic/lipophobic barriers and graphene quantum dots for recognition and quantification of the hemostatic drug carbazochrome, via fluorescence turn-off mechanism mediated by the inner filter effect. A smartphone-based all-in-one device fitted with an inexpensive 365 nm flashlight as a UV light source and a free image processing software was developed for rapid and reliable interpretation of the fluorescence change from the paper-based device upon introduction of the drug. The simple and convenient steps permit the analysis of many samples in a very short time. The smartphone-based all-in-one device featured excellent sensitivity for carbazochrome with a limit of detection equals to 12 ng/detection zone and good %recovery (100.0 ± 0.4). The reliability of the device was ascertained by favorable statistical comparison with the analogous optimized conventional fluorimetry method and a reference HPLC method. The device has been successfully applied for versatile quantitation of carbazochrome in tablets and on manufacturing equipment surfaces with excellent recoveries. The device offers many green aspects that definitely assist the implementation of the sustainability concept to analytical laboratories. The cost-efficiency, reliability, and ease of fabrication as well as the greenness and user friendship qualify the device for wide application in low-income communities.

The Effect of Carbazochrome Sodium Sulfonate in Patients with Colonic Diverticular Bleeding: Propensity Score Matching Analyses Using a Nationwide Inpatient Database.

Objective Carbazochrome sodium sulfonate (CSS) has been routinely used to treat bleeding; however, no study has examined the effect of CSS for gastrointestinal bleeding. Therefore, we aimed to investigate the effect of CSS for colonic diverticular bleeding. Methods We performed a nationwide observational study using the Japanese Diagnosis Procedure Combination inpatient database. We identified patients who were admitted for diverticular bleeding from July 2010 to March 2018. Patients who received CSS on the day of admission were defined as the CSS group, and those not receiving CSS were defined as the control group. The primary outcome was in-hospital mortality. Secondary outcomes were length of stay, total costs, and blood transfusion within 7 days of admission. Propensity score matching analyses were performed to compare outcomes between the two groups. Results A total of 59,965 patients met our eligibility criteria. Of these, 14,437 (24%) patients received CSS on the day of admission. One-to-one propensity score matching created 14,379 matched pairs. There was no significant difference in the in-hospital mortality between the CSS and control groups (0.6% vs. 0.5%, respectively; odds ratio: 0.96; 95% confidence interval: 0.72-1.29). The length of stay was longer in the CSS group than in the control group (11.4 vs. 11.0 days, respectively; difference: 0.44; 95% confidence interval: 0.14-0.73). There were no significant differences in the total costs or the proportion of patients receiving blood transfusion between the groups. Conclusions CSS may not reduce in-hospital mortality, length of stay, total costs, or the need for blood transfusion in patients with colonic diverticular bleeding.

Hemostatic and Anti-Inflammatory Effects of Carbazochrome Sodium Sulfonate in Patients Undergoing Total Knee Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: Postoperative recovery after total knee arthroplasty (TKA) is associated with postoperative anemia, allogeneic transfusion, and stress immune responses to surgery. Carbazochrome sodium sulfonate (CSS) reduces bleeding through several mechanisms. We assessed the effect of CSS combined with tranexamic acid (TXA) on postoperative anemia, blood transfusion, and inflammatory responses. METHODS: This study was designed as a randomized, placebo-controlled trial of 200 patients undergoing unilateral primary TKA. Patients were divided into 4 groups: group A received TXA plus topical and intravenous CSS; group B received TXA plus topical CSS only; group C received TXA plus intravenous CSS only; group D received TXA only. RESULTS: Total blood loss in groups A (609.92 ± 221.24 mL), B (753.16 ± 247.67 mL), and C (829.23 ± 297.45 mL) was lower than in group D (1158.26 ± 334.13 mL, P < .05). There was no difference in total blood loss between groups B and C. We also found that compared with group D, the postoperative swelling rate, biomarker level of inflammation, visual analog scale pain score, and range of motion at discharge in groups A, B, and C were significantly improved (P < .05). No thromboembolic complications occurred. There were no differences in transfusion rate, intraoperative blood loss, platelet count, or average length of stay among the 4 groups (P > .05). CONCLUSION: CSS combined with TXA was more effective than TXA alone in reducing perioperative blood loss and inflammatory response and did not increase the incidence of thromboembolism complications.

A randomized, double-blind, placebo-controlled multicenter study for evaluating the effects of fixed-dose combinations of vitamin C, vitamin E, lysozyme, and carbazochrome on gingival inflammation in chronic periodontitis patients.

BACKGROUND: To evaluate gingival inflammation from fixed-dose combinations of vitamin C, vitamin E, lysozyme and carbazochrome (CELC) in the treatment of chronic periodontitis following scaling and root planing. METHODS: One hundred patients were randomly assigned to receive CELC (test) or placebo (control) for the first 4 weeks at a 1:1 ratio, and both groups received CELC for the remaining 4 weeks. Primary outcome was the mean change in the gingival index (GI) after 4 weeks. Secondary outcomes included mean change in GI after 8 weeks and plaque index, probing depth, clinical attachment level, and VAS at 4 weeks and 8 weeks. RESULTS: Ninety-three patients completed the study. The GI in the test group significantly decreased after 4 weeks (p < 0.001) and 8 weeks (p < 0.001). The mean change from baseline in GI significantly decreased in the test group compared to the control group after 4 weeks (p = 0.015). In the GEE model adjusting for age, gender and visits, the test group showed 2.5 times GI improvement compared to the control group (p = 0.022). CONCLUSIONS: Within the study, CELC showed a significant reduction in gingival inflammation compared with a placebo. Other parameters, however, were similar between groups. TRIAL REGISTRATION: KCT0001366 (Clinical Research Information Service, Republic of Korea) and 29 Jan 2015, retrospectively registered.

Pelvic venous congestion induces lower urinary tract dysfunction in rats.

Pelvic venous congestion (PC) is thought to be related to several diseases of the lower urinary tract (LUT). We examined the characteristics of the LUT in rats with PC. To create PC, female rats were anesthetized with isoflurane, and the bilateral common iliac veins and bilateral uterine veins were ligated. At 1-8 weeks after either ligation or sham surgery, we performed cystometry with or without administration of carbazochrome sodium sulfonate hydrate or propiverine hydrochloride, histologic examination of the bladder, blood flow imaging, assessment of locomotor activity, measurement of urinary 8-hydroxydeoxyguanosine (8-OHdG) and nitric oxide metabolites (NOx), and the Evans blue dye extravasation test. PC elevated frequency of urination after 2-6 weeks, and caused a decrease of spontaneous locomotor activity. In addition, there was a decrease of bladder blood flow, an increase of bladder vascular permeability, an increase of urinary 8-OHdG, a decrease of urinary NOx, and mild inflammatory changes of the bladder. In rats with PC, frequency of urination was normalized by administration of propiverine or carbazochrome. Rats with PC may be used as a model of PC associated with high frequency of urination, and this model may be useful when developing treatment for LUT symptoms associated with PC.

Dynamic agent of an injectable and self-healing drug-loaded hydrogel for embolization therapy.

Embolic agents are crucial for trans-catheter arterial embolization (TAE) in the treatment of various unresectable malignant tumors. Although solid particles, liquid oils, and some polymeric hydrogels have proved their capacities for embolic therapies, the low efficiency, time sensitivity, and cytotoxicity are still considered as challenges. In this study, we developed a three-component dynamic self-healing hydrogel to overcome these limitations. With the help of the Schiff-base bonding, both glycol-chitosan and carbazochrome, containing amine groups, react with dibenzaldehyde-terminated poly(ethylene-glycol) (DF-PEG), forming the dynamic self-healing hydrogels under a mild condition within 200 s. 1H NMR and rheology test were used to characterize the Schiff-base formation and mechanical strength. Controlled-release of carbazochrome from different gelator concentrations of DF-PEG was also studied. Furthermore, in vivo evaluation of the embolization on rats showed the superior embolic effects of the injectable and self-healing hydrogel. Therefore, this new dynamic agent demonstrated the potential for application as a simple, inexpensive, and tunable embolic agent for cancer treatment and drug delivery system.

Validated spectrophotometric methods for simultaneous determination of troxerutin and carbazochrome in dosage form.

Four simple, accurate, sensitive and precise spectrophotometric methods were developed and validated for simultaneous determination of Troxerutin (TXN) and Carbazochrome (CZM) in their bulk powders, laboratory prepared mixtures and pharmaceutical dosage forms. Method A is first derivative spectrophotometry (D(1)) where TXN and CZM were determined at 294 and 483.5 nm, respectively. Method B is first derivative of ratio spectra (DD(1)) where the peak amplitude at 248 for TXN and 439 nm for CZM were used for their determination. Method C is ratio subtraction (RS); in which TXN was determined at its λmax (352 nm) in the presence of CZM which was determined by D(1) at 483.5 nm. While, method D is mean centering of the ratio spectra (MCR) in which the mean centered values at 300 nm and 340.0 nm were used for the two drugs in a respective order. The two compounds were simultaneously determined in the concentration ranges of 5.00-50.00 µg mL(-1) and 0.5-10.0 µg mL(-1) for TXN and CZM, respectively. The methods were validated according to the ICH guidelines and the results were statistically compared to the manufacturer's method.

Effect of carbazochrome sodium sulfonate on refractory chronic prostatitis.

OBJECTIVES: To study the effect of carbazochrome sodium sulfonate, an agent that reduces capillary permeability, on refractory chronic prostatitis. METHODS: Patients with prostatitis refractory to at least 8 weeks of routine therapy and with urinalysis positive for microhematuria were considered for the present study. In addition to their prior therapy, the patients received carbazochrome at a dose of 30 mg three times a day. The severity of pain (score 0-10), daytime and night-time frequency, international prostate symptom score, global self-assessment, urine occult blood positivity, and adverse events were assessed after 4 and 8 weeks of treatment, and compared with baseline findings. RESULTS: A total of 50 patients (mean age 68.6 ± 8.5 years) were evaluable. The pain score decreased significantly from 3.2 ± 2.1 at baseline to 1.7 ± 1.4 after 4 weeks of treatment and to 1.1 ± 1.8 after 8 weeks. Daytime and night-time frequency, storage symptoms, post-micturition symptoms, and urine occult blood positivity also significantly improved. More than 36% of the patients gave a global self-assessment rating of "improved" or "better" after both 4 and 8 weeks of treatment. Mild adverse events occurred in three patients; one had nausea and two developed drug rash. CONCLUSIONS: Carbazochrome seems to effectively improve pain as well as storage and post-micturition symptoms in patients with refractory chronic prostatitis.

Optimization of solid phase extraction clean up and validation of quantitative determination of carbazochrome sodium sulfonate in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry.

A mixed-mode anion exchange solid phase extraction (SPE) method for extraction and clean up of carbazochrome sodium sulfonate (CSS) and (1S)-(+)-10-camphorsulfonic acid (IS) was optimized for quantification by high-performance liquid chromatography/negative electrospray ionization mass spectrometry. The analytes were extracted from 1mL of human plasma via SPE on Oasis(®) WAX cartridge. Chromatographic separation was achieved on a Zorbax SB-Aq (4.6×250mm, 5µm) column under an isocratic condition. Detection was performed using electrospray ionization in negative ion multiple reaction monitoring (MRM) mode. The deprotonated precursor to product ion transitions monitored for CSS and IS was at m/z 299.0→256.0 and m/z 230.9→79.8, respectively. The method was fully validated for its selectivity, sensitivity, precision, accuracy, recovery, matrix effect and stability. Linear range was 0.189-37.8ng/mL with a high square regression coefficient (r=0.9995). The intra-and inter-day precision (RSD, %) ranged from 0.95% to 4.17%, and the intra-and inter-day accuracy was between 95.03% and 105.9%. This method was successfully applied to a bioequivalence study of 90mg CSS formulation in 18 healthy Chinese male subjects under fasting condition.

A novel blending method for dispensing powdered medicine.

We introduced the application of a planetary centrifugal mixer to dispensing powdered medicines to prevent from individual variation in the skills of pharmacists with a manual blending. The blending performance of the mixer was explored in terms of four operational variables, namely, operation speed (400-1000 rpm), operation time (10-60 s), charging rate in vessel (20-50%), and size of vessel (35, 58, 125, 550 mL), using colored lactose and crystalline lactose as the principle model medicine and diluent, respectively. The blending degree was assessed by image analysis, so the extent of uniformity was expressed as the relative standard deviation of the color difference signal Cb value of YCrCb color space. Application of the mixer to blending three commercial medicines with diluents was carried out. Sufficient blending was achieved at 10 s using a 20% charging rate and 35 mL vessel irrespective of operation speed. As the charging rate was increased, a higher operation speed was needed to obtain uniform blending. A larger sized vessel also required a higher operation speed. Uniform blending was achieved in all of the mixtures of colored lactose and crystalline lactose at the weight ratio of 1 : 9-9 : 1. In the application studies using Adona®, Anginal® and Neophylline® powder, the blending performance of the mixer was equivalent to that of the manual blending method, showing relative standard deviations of 2.2-3.3% and 1.8-3.8%, respectively. These results revealed that the planetary centrifugal mixer was suitable for blending powdered medicine.

High-dose tranilast administration to rats creates interstitial cystitis-like symptoms with increased vascular permeability.

AIM: We investigated whether the high-dose administration of tranilast could be used to create an animal model of interstitial cystitis (IC). Then, we used this model to assess the relationship between IC and changes in the vascular permeability of the bladder. MAIN METHODS: Female rats were divided into the following 4 groups: a control group, a tranilast group, a carbazochrome group and a combination (tranilast+carbazochrome) group. Continuous cystometry, bladder distension, and the Evans blue dye extravasation test were performed 4weeks after drug administration. Locomotor activity, the plasma TGF-ß1 level, and collagen fibers in the bladder wall were also examined in the control and tranilast groups. KEY FINDINGS: The interval between bladder contractions was shorter and the leakage of Evans blue dye into the bladder wall was greater in the tranilast group than in the control group. Glomerulations of the bladder wall after bladder distention and thinning of the collagen fiber layer in the bladder were observed in the tranilast group. Locomotor activity in darkness and the plasma TGF-ß1 level were both lower in the tranilast group than in the control group. In the combination group, the leakage of Evans blue dye was greater than in the control group; however, it was less prominent than in the tranilast group. SIGNIFICANCE: These results suggest that high-dose administration of tranilast to rats can create an IC-like rat model and that an increase in the vascular permeability of the bladder wall may be one cause of IC symptoms.

Multiple targeted drugs carrying biodegradable membrane barrier: anti-adhesion, hemostasis, and anti-infection.

A multiple targeted drug carrying bilayer membrane for preventing an abdominal adhesion is prepared by electrospinning. Two bioactive drugs were successfully incorporated into this bilayer membrane and can be independently released from nanofibrous scaffolds without losing structural integrity and functionality of the anti-adhesion membrane. Besides, the drug release profile could be easily adjusted by optimizing the swelling behavior of the fibrous scaffold. The inner layer of the bilayered fibrous membranes loaded with carbazochrome sodium sulfonate (CA) showed an excellent vascular hemostatic efficacy and formed little clot during in vivo experiment. The outer layer loaded with tinidazole (TI) had outstanding antibacterial effect against the anaerobe. We believe this approach could serve as a model technique to guide the design of implants with drug delivery functions.

Fluorescence quenching method for the determination of carbazochrome sodium sulfonate with aromatic amino acids.

In Britton-Robinson (BR) buffer medium (pH 3.3), carbazochrome sodium sulfonate (CSS) can react with some aromatic amino acids such as tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe) to form a 1:1 complex by electrostatic attraction, aromatic stacking interaction and Van der Waals' force, resulting in fluorescence quenching of these amino acids. Maximum quenching wavelengths were located at 352 nm (CSS-Trp system), 303 nm (CSS-Tyr system) and 284 nm (CSS-Phe system), respectively. The fluorescence quenching value (ΔF) was proportional to the concentration of CSS in a certain range. The fluorescence quenching method for the determination of CSS showed high sensitivity, with detection limits of 31.3 ng/mL (CSS-Trp system), 44.6 ng/mL (CSS-Tyr system) and 315.0 ng/mL (CSS-Phe system), respectively. The optimum conditions of the reaction conditions and the effect of coexisting substances were investigated and results showed that the method had good selectivity. The method was successfully applied for the rapid determination of CSS in blood and urine samples. Based on the bimolecular quenching constant Kq , the effect of temperature and Stern-Volmer plots, this study showed that quenching of fluorescence of amino acids by CSS was a static quenching process.

Determination of carbazochrome by fluorescence quenching method.

A sensitive, simple and selective spectrofluorimetric method for the reaction of carbazochrome (CBZC) and Eosin Y (EY) or Phloxine B (PB) in acidic medium is developed for the determination of carbazochrome in biological fluids, which gives a highly fluorescent derivative measured at 545 and 565 nm at excitation wavelengths of 301 and 305 nm. The fluorescence quenching extent (ΔF) is proportional to the concentration of CBZC for CBZC-EY and CBZC-PB system at the range of 0.03-1.50 µg/mL and 0.08-1.25 µg/mL, respectively. The detection limit is 9.1 ng/mL for EY system and 22.7 ng/mL for PB system. The intra-day and inter-day reproducibility (RSD values) are less than 8.3% under three concentrations. Moreover, the affecting factors of fluorescence intensity of the product are carefully investigated and optimized, as well as the effect of coexisting substances. Judging from temperature, the Stern-Volmer plots and fluorescence emission decay curves, the quenching of fluorescence of EY and PB by CBZC is a static quenching process, caused by electrostatic attraction and aromatic stacking interaction.