Simultaneous fluorescence and Compton scattering computed tomography based on linear polarization X-ray

Purpose To propose a method for simultaneous fluorescence and Compton scattering computed tomography by using linearly polarized X-rays.Methods Monte Carlo simulations were adopted to demonstrate the feasibility of the proposed method.In the simulations,the phantom is a polytetrafluoroethylene cylinder inside which are cylindrical columns containing aluminum,water,and gold(Au)-loaded water solutions with Au concentrations ranging between 0.5 and 4.0 wt%,and a parallel-hole collimator imaging geometry was adopted.The light source was modeled based on a Thomson scattering X-ray source.The phantom images for both imaging modalities were reconstructed using a maximumlikelihood expectation maximization algorithm.Results Both the X-ray fluorescence computed tomography(XFCT)and Compton scattering computed tomography(CSCT)images of the phantom were accurately reconstructed.A similar attenuation contrast problem for the different cylindrical columns in the phantom can be resolved in the XFCT and CSCT images.The interplay between XFCT and CSCT was analyzed,and the contrast-to-noise ratio(CNR)of the reconstruction was improved by correcting for the mutual influence between the two imaging modalities.Compared with K-edge subtraction imaging,XFCT exhibits a CNR advantage for the phantom.Conclusion Simultaneous XFCT and CSCT can be realized by using linearly polarized X-rays.The synergy between the two imaging modalities would have an important application in cancer radiation therapy.

Superiority of indocyanine green-enhanced near-infrared fluorescence-guided imaging for laparoscopic lymph node dissection in patients with early-stage endometrial cancer: A retrospective cohort study

Objective:Laparoscopic pelvic lymph node dissection(LPND),which is an effective therapy for endometrial cancer,is challenging because of the complexity of the procedure and the occurrence of postoperative complications.This study aimed to explore whether indocyanine green(ICG)-enhanced nearinfrared(NIR)fluorescence-guided LPND is superior to LPND in the context of early-stage endometrial carcinoma.Methods:In this retrospective study,we included the medical records of 190 patients with early-stage endometrioid adenocarcinoma who underwent LPND at the Department of Obstetrics and Gynecology,Sir Run Run Shaw Hospital,Zhejiang University School of Medicine between January 2019 and January 2021.Depending on whether ICG-enhanced NIR fluorescence guidance was used,the patients were assigned to the ICG group or non-ICG group.Patients were followed-up for one year after surgery.Data on demographic characteristics,pathological results,operative outcomes,and complications were collected and analyzed.Results:The baseline characteristics were comparable between the ICG group and non-ICG group,including age,BMI,pregnancy history,and preoperative hemoglobin.For surgical outcomes,the patients in ICG group had significantly lower intraoperative blood loss(50 mL vs.120 mL,p<0.001),less postoperative pelvic drainage time(4.14±1.44 d vs.5.70±1.89 d,p¼0.001),shorter duration of hospital stay(5.26±1.41 d vs.7.37±1.85 d,p¼0.003),higher number of positive pelvic lymph nodes(PLNs)(1 vs.0,p¼0.003),and more PLN-positive cases(16.0%vs.3.6%,p¼0.003)than the patients in non-ICG group.However,no significant differences were noted in blood transfusion requirement,operative time,hemoglobin level decreases,number of PLNs harvested,or the presence of lymphocysts between the two groups.Conclusion:Our study showed that ICG-enhanced NIR fluorescence-guided operation may improve the accuracy and safety of LPND.

Near-infrared cholangiography with intragallbladder indocyanine green injection in minimally invasive cholecystectomy

Laparoscopic cholecystectomy(LC)remains one of the most commonly performed procedures in adult and paediatric populations.Despite the advances made in intraoperative biliary anatomy recognition,iatrogenic bile duct injuries during LC represent a fatal complication and consist an economic burden for healthcare systems.A series of methods have been proposed to prevent bile duct injury,among them the use of indocyanine green(ICG)fluorescence.The most commonly reported method of ICG injection is the intravenous administration,while literature is lacking studies investigating the direct intragallbladder ICG injection.This narrative mini-review aims to assess the potential applications,usefulness,and limitations of intragallbladder ICG fluorescence in LC.Authors screened the available international literature to identify the reports of intragallbladder ICG fluorescence imaging in minimally invasive cholecystectomy,as well as special issues regarding its use.Literature search retrieved four prospective cohort studies,three case-control studies,and one case report.In the three case-control studies selected,intragallbladder near-infrared cholangiography(NIRC)was compared with standard LC under white light,with intravenous administration of ICG for NIRC and with standard intraoperative cholangiography(IOC).In total,133 patients reported in the literature have been administered intragallbladder ICG administration for biliary mapping during LC.Literature includes several reports of intragallbladder ICG administration,but a standardized technique has not been established yet.Published data suggest that NIRC with intragallbladder ICG injection is a promising method to achieve biliary mapping,overwhelming limitations of IOC including intervention and radiation exposure,as well as the high hepatic parenchyma signal and time interval needed in intravenous ICG fluorescence.Evidence-based guidelines on the role of intragallbladder ICG fluorescence in LC require the assessment of further studies and multicenter data collection into large registries.

Near-infrared fluorescence sentinel lymph node detection in gastric cancer: A pilot study

AIM: To investigate feasibility and accuracy of near-infrared fluorescence imaging using indocyanine green: nanocolloid for sentinel lymph node (SLN) detection in gastric cancer.METHODS: A prospective, single-institution, phase I feasibility trial was conducted. Patients suffering from gastric cancer and planned for gastrectomy were included. During surgery, a subserosal injection of 1.6 mL ICG:Nanocoll was administered around the tumor. NIR fluorescence imaging of the abdominal cavity was performed using the Mini-FLARE&#x02122; NIR fluorescence imaging system. Lymphatic pathways and SLNs were visualized. Of every detected SLN, the corresponding lymph node station, signal-to-background ratio and histopathological diagnosis was determined. Patients underwent standard-of-care gastrectomy. Detected SLNs outside the standard dissection planes were also resected and evaluated.RESULTS: Twenty-six patients were enrolled. Four patients were excluded because distant metastases were found during surgery or due to technical failure of the injection. In 21 of the remaining 22 patients, at least 1 SLN was detected by NIR Fluorescence imaging (mean 3.1 SLNs; range 1-6). In 8 of the 21 patients, tumor-positive LNs were found. Overall accuracy of the technique was 90% (70%-99%; 95%CI), which decreased by higher pT-stage (100%, 100%, 100%, 90%, 0% for respectively Tx, T1, T2, T3, T4 tumors). All NIR-negative SLNs were completely effaced by tumor. Mean fluorescence signal-to-background ratio of SLNs was 4.4 (range 1.4-19.8). In 8 of the 21 patients, SLNs outside the standard resection plane were identified, that contained malignant cells in 2 patients.CONCLUSION: This study shows successful use of ICG:Nanocoll as lymphatic tracer for SLN detection in gastric cancer. Moreover, tumor-containing LNs outside the standard dissection planes were identified.

Evaluation of COC183B2 antibody targeting ovarian cancer by near-infrared fluorescence imaging

Objective: To evaluate the imaging potential of a novel near-infrared(NIR) probe conjugated to COC183 B2 monoclonal antibodies(MAb) in ovarian cancer(OC).Methods: The expression of OC183 B2 antigen in OC was determined by immunohistochemical(IHC) staining using tissue microarrays with the H-score system and immunofluorescence(IF) staining of tumor cell lines.Imaging probes with the NIR fluorescent dye cyanine 7(Cy7) conjugated to COC183 B2 Mab were chemically engineered. OC183 B2-positive human OC cells(SKOV3-Luc) were injected subcutaneously into BALB/c nude mice. Bioluminescent imaging(BLI) was performed to detect tumor location and growth. COC183 B2-Cy7 at 1.1,3.3, 10, or 30 μg were used for in vivo fluorescence imaging, and phosphate-buffered saline(PBS), free Cy7 dye and mouse isotype immunoglobulin G(IgG)-Cy7(delivered at the same doses as COC183 B2-Cy7) were used as controls.Results: The expression of OC183 B2 with a high H-score was more prevalent in OC tissue than fallopian tube(FT) tissue. Among 417 OC patients, the expression of OC183 B2 was significantly correlated with the histological subtype, histological grade, residual tumor size, relapse state and survival status. IF staining demonstrated that COC183 B2 specifically expressed in SKOV3 cells but not HeLa cells. In vivo NIR fluorescence imaging indicated that COC183 B2-Cy7 was mainly distributed in the xenograft and liver with optimal tumor-to-background(T/B)ratios in the xenograft at 30 μg dose. The highest fluorescent signals in the tumor were observed at 96 h postinjection(hpi). Ex vivo fluorescence imaging revealed the fluorescent signals mainly from the tumor and liver. IHC analysis confirmed that xenografts were OC183 B2 positive.Conclusions: COC183 B2 is a good candidate for NIR fluorescence imaging and imaging-guided surgery in OC.

Advances in surgical techniques for gastric cancer:Indocyanine green and near-infrared fluorescence imaging.Is it ready for prime time?

Surgery is still the primary curative treatment for gastric cancer,which includes resection of the tumor with adequate margins and extended lymphadenectomy.In order to improve the operative results and the quality of life of patients,several endeavors have been made toward precision medicine through image-guided surgery,allowing access to real-time intraoperative anatomy and accurate tumor staging.The goal of the surgeon is to achieve a more precise,individualized,and less invasive surgery without compromising oncological efficiency and safety.In this perspective,we have demonstrated the role of indocyanine green(ICG)and near-infrared(NIR)fluorescence imaging method in gastric cancer surgery.This technique may be used to improve localization of the tumor,detection of sentinel lymph nodes(SLN),real-time lymphatic mapping,and blood flow assessment(anastomosis perfusion).

Study of Imidazolium Ionic Liquids:Temperature-dependent Fluorescence and Molecular Dynamics Simulation

The steady-state fluorescence spectra and molecular dynamics simulations were explored to investigate the temperature dependent organization in some imidazolium ionic liquids：1-butyl-3-methylimidazolium hexafluo-rophosphate（[bmim][PF6]）,1-ethyl-3-methylimidazolium ethylsulfate（[emim][EtSO4]） and 1-butyl-3-methylimida-zolium tetrafluoroborate（[bmim][BF4]）.The pure room temperature ionic liquids（ILs） exhibit a large red shift at more than an excitation wavelength of around 340 nm,which demonstrates the heterogeneous nature of the liquids.Furthermore,the fluorescence spectra of the ionic liquids were found to be temperature-dependent.The emission intensity gradually decreased with increasing temperature for the neat ionic liquids and the mixed solutions of [bmim][BF4]-H2O,which was the special phenomena induced by not only the local structure but also the viscosity.The molecular dynamics simulation further confirms that the structures of ionic liquids are sensitive to the surroun-ding environment because of the aggregation degree of ILs.

Near-infrared fluorescence guided esophageal reconstructive surgery: A systematic review

BACKGROUND After an esophagectomy, the stomach is most commonly used to restore continuity of the upper gastrointestinal tract. These esophago-gastric anastomoses are prone to serious complications such as leakage associated with high morbidity and mortality. Graft perfusion is considered to be an important predictor for anastomotic integrity. Based on the current literature we believe Indocyanine green fluorescence angiography(ICGA) is an easy assessment tool for gastric tube(GT) perfusion, and it might predict anastomotic leakage(AL).AIM To evaluate feasibility and effectiveness of ICGA in GT perfusion assessment and as a predictor of AL.METHODS This study was designed according to the PRISMA guidelines and registered in the PROSPERO database. PubMed and EMBASE were independently searched by 2 reviewers for studies presenting data on intraoperative ICGA GT perfusion assessment during esophago-gastric reconstruction after esophagectomy.Relevant outcomes such as feasibility, complications, intraoperative surgical changes based on ICGA findings, quantification attempts, anatomical data and the impact of ICGA on postoperative anastomotic complications, were collected by 2 independent researchers. The quality of the included articles was assessed based on the Methodological Index for Non-Randomized Studies. The 19 included studies presented data on 1192 esophagectomy patients, in 758 patients ICGA was used perioperative to guide esophageal reconstruction.RESULTS The 19 included studies for qualitative analyses all described ICGA as a safe and easy method to evaluate gastric graft perfusion. AL occurred in 13.8% of the entire cohort, 10% in the ICG guided group and 20.6% in the control group(P <0.001). When poorly perfused cases are excluded from the analyses, the difference in AL was even larger(AL well-perfused group 6.3% vs control group 20.5%, P <0.001). The AL rate in the group with an altered surgical plan based on the ICG image was 6.5%, similar to the well perfused group(6.3%) and significantly less than the poorly perfused group(47.8%)(P < 0.001), suggesting that the technique is able to identify and alter a potential bad outcome.CONCLUSION ICGA is a safe, feasible and promising method for perfusion assessment. The lower AL rate in the well perfused group suggest that a good fluorescent signal predicts a good outcome.

Simulation Study of Quantitative X-Ray Fluorescence Analysis of Ore Slurry Using Partial Least-Squares Regression

X-ray fluorescence （XRF） in combination with partial least-squares （PLS） regression was employed to analyze the ore slurry grade. Using the Monte Carlo simulation code PENELOPE, X-ray fluorescence spectra of ore samples were obtained. Good accuracy was achieved when this method was used to analyze elements with concentrations of several percent or above. It was demonstrated that the more the number of X-ray fluorescence spectra used to calibrate, the better the obtained accuracy. In this method detector resolution was found to have little or no effect on the results of quantitative analysis. The effect of the concentration of water was investigated as well, and it was found to have little influence on the results.

Mechanism of Dynamic Near-infrared Fluorescence Cholangiography of Extrahepatic Bile Ducts and Applications in Detecting Bile Duct Injuries Using Indocyanine Green in Animal Models

Fluorescence intraoperative cholangiography（IOC） is a potential alternative for identifying anatomical variation and preventing iatrogenic bile duct injuries by using the near-infrared probe indocyanine green（ICG）. However, the dynamic process and mechanism of fluorescence IOC have not been elucidated in previous publications. Herein, the optical properties of the complex of ICG and bile, dynamic fluorescence cholangiography and iatrogenic bile duct injuries were investigated. The emission spectrum of ICG in bile peaked at 844 nm and ICG had higher tissue penetration. Extrahepatic bile ducts could fluoresce 2 min after intravenous injection, and the fluorescence intensity reached a peak at 8 min. In addition, biliary dynamics were observed owing to ICG excretion from the bile ducts into the duodenum. Quantitative analysis indicated that ICG-guided fluorescence IOC possessed a high signal to noise ratio compared to the surrounding peripheral tissue and the portal vein. Fluorescence IOC was based on rapid uptake of circulating ICG in plasma by hepatic cells, excretion of ICG into the bile and then its interaction with protein molecules in the bile. Moreover, fluorescence IOC was sensitive to detect bile duct ligation and acute bile duct perforation using ICG in rat models. All of the results indicated that fluorescence IOC using ICG is a valid alternative for the cholangiography of extrahepatic bile ducts and has potential for measurement of biliary dynamics.

A SIMULATION STUDY ON DYNAMIC-SAMPLING-MODE FOR FLUORESCENCE MOLECULAR TOMOGRAPHY

Fluorescence tomography can obtain a sufficient dataset and optimal three-dimensional imageswhen projections are captured over 360◦ by CCD camera. Herein a non-stop dynamic samplingmode for fluorescence tomography is proposed in an attempt to improve the optical measurementspeed of the traditional imaging system and stability of the object to be imaged. A series ofsimulations are carried out to evaluate the accuracy of dataset acquired from the dynamicsampling mode. Reconstruction with the corresponding data obtained in the dynamic-modeprocess is also performed with the phantom. The results demonstrate the feasibility of suchan imaging mode when the angular velocity is set to the appropriate value, thus laying thefoundation for real experiments to verify the superiority in performance of this new imagingmode over the traditional one.

Semi-analytical Monte Carlo simulation of laser-induced fluorescence propagation in an optically participating spray

A semi-analytical Monte Carlo (SMC) simulation was developed to simulate the propagation of laser-induced fluo- rescence (LIF) in an optically participating spray, which simultaneously exhibits spectrally dependent emission, anisotropic scattering, absorption, and re-emission. The SMC simulation is described and then applied to an experimental configuration of a cloud of polydisperse droplets composed of water and sulforhodamine B dye. In the SMC simulation, the collected LIF flux on the remote receptor element is calculated as the global contribution from the emissive source, single, twice, … and nth collision events in any sequence. The effects on the fluorescence photons propagation of spray parameters like the dye concentration, droplets concentration, and droplets size are examined. Three spectral bands representing different optical properties are chosen to analyze the interference of absorption, scattering and re-emission on the detected LIF flux. The obtained spectral LIF flux distribution on the receptor demonstrates a “red shift” phenomenon.

Simulation and Design of Fluorescence Collector

Fluorescence collector is a critical component in optically pumped Cs beam frequency standards. We design a new fluorescence collector by means of a new method. By means of two simulation methods, a smaller fluorescence collector with the same collection efficiency is achieved. It can be applied to almost all fluorescence detection systems in atom-light interaction experiments. We select the practical fluorescence collector studied by comparing three designing schemes. Its structure is very plain. Moreover, its fluorescence collection efficiency is very high. The collection efficiency of the practical fluorescence collector we designed is over 33% by means of two different ways.

Novel imaging system for positioning of the indocyanine green (ICG) target;visible projection of the near-infrared fluorescence image

Background: Even though NIR fluorescence imaging has many advantages in SLN mapping and cancer detection, NIR fluorescence imaging shows a serious drawback that NIR cannot be detected by the naked eye without any detectors. This limitation further disturbs accurate SLN detection and adequate tumor resection resulting in the presence of cancerous cells near the boundaries of surgically removed tissues. Materials and methods: To overcome the drawback of the conventional NIR imaging method, we suggest a novel NIR imaging system which can make the NIR fluorescence image visible to the naked eye as NIR fluorescence image detected by a video camera is processed by a computer and then projected back onto the NIR fluorescence excitation position with a projector using conspicuous color light. Image processing techniques were used for projection onto the exact position of the NIR fluorescence image. Also, we implemented a phantom experiment to evaluate the performance of the developed NIR fluorescence projection system by use of the ICG. Results: The developed NIR fluorescence projection system was applied in normal mouse model to confirm the usefulness of the system in the clinical field. A BALB/c nude mouse was prepared to be applied in normal mouse model and 0.25 mg/ml stock solution of the ICG was injected through a tail vein of the mouse. From the application in normal mouse model, we could confirm that the injected ICG stayed in the liver of the mouse and verify that the projection system projected the ICG fluorescence image at the exact location of the ICG by performing laparotomy of the mouse. Conclusions: From the application in normal mouse model, we could verify that the ICG fluorescence image was precisely projected back on the site where ICG fluorescence generated. It can be demonstrated that the NIR fluorescence projection system can make it possible to visualize the invisible NIR fluorescence image and to realize that SLN mapping and cancer detection in clinical surgery.

Optical Probe for Near-Infrared (NIR) Fluorescence Signal Detection with High Optical Performance and Thermal Stability

We propose a new optical probe for near-infrared (NIR) fluorescence signal detection with high optical performance and thermal stability. The optical probe is composed of an optical source part for efficient excitation of NIR fluorescence signal, a heat dissipation part for stable operation of the NIR fluorescence probe, and an optical detection part for efficient detection of NIR fluorescence signal. From a simulation by use of an optical simulation tool, Light ToolsTM, we could confirm that the optical probe has optical propagation efficiency of 79.6% in case of using a circular detector with 20 cm in diameter located at 20 cm in distance from the optical source. From a measurement of temperature variation of the optical probe, we could also confirm that the optical probe has thermal stability with a standard deviation of 2.19&deg;C under room temperature condition. Finally, from an evaluation of fluorescence image quality, we could confirm that an optical noise which can bring on by overlapped band between optical spectrum of the optical source for fluorescence excitation and optical spectrum of the emitted fluorescence signal decreased effectively in the optical probe.

Methods to Minimize Optical Noise That Degrade Fluorescence Efficiency of Optical Probe for Near-Infrared Tracking in Surgical Environment

In the medical field, there are growing interests in applied research such as in vivo fluorescence monitoring because of excellent body transmission characteristic of the near-infrared light. However, optical noise by excitation light and illumination equipment for medical applications such as interior light, surgical light decrease efficiency of the fluorescent signal when observers such as surgeons confirm fluorescence signals in medical field. To solve these problems in medical field, we have analyzed external noise factors by effect on image realization, quantification of optical noise generation by external factors, and have suggested methods of minimize the optical noise in this paper. In case of fluorescence imaging in the operating room, it has been confirmed that fluorescent excitation light, interior light and surgical light are factors to generate optical noise. To acquire near-infrared fluorescence images and to compare fluorescence contrast under conditions of darkroom, interior light and surgical light, light emitting diodes (LEDs) sources that have peak wavelength at 740, 760 and 780 nm respectively were used as excitation light sources. In addition, short-pass filter which has transmission edge at 775 nm has been applied to minimize the optical noise in each external noise factor. By comparing contrast of each image before and after use of the short-pass filter, we confirmed that optical noise reduced 49%, 56% and 66% in external noise factors respectively.

Noninvasive in vivo study of NADH fluorescence and its real-time intrinsic dynamical changes: Experiments and seven-layered skin model Monte Carlo simulations

Reduced nicotinamide adenine dinucleotide(NADH)plays a crucial role in many biochemical reactions in human metabolism.In this work,a flow-mediated skin fluorescence(FMSF)-postocclusion reactive hyperaemia(PORH)system was developed for noninvasive and in vivo measurement of NADH fluorescence and its real-time dynamical changes in human skin tissue.The real-time dynamical changes of NADH fluorescence were analyzed with the changes of skin blood flow measured by laser speckle contrast imaging(LSCI)experiments simultaneously with FMSFPORH measurements,which suggests that the dynamical changes of NADH fluorescence would be mainly correlated with the intrinsic changes of NADH level in the skin tissue.In addition,Monte Carlo simulations were applied to understand the impact of optical property changes on the dynamical changes of NADH fluorescence during the PORH process,which further supports that the dynamical changes of NADH fluorescence measured in our system would be intrinsic changes of NADH level in the skin tissue.

Recent developments of fluorescence imaging technology in the second near-infrared window

Background:Fluorescence bio-imaging in the second near-infrared window(NIR-II FL,1000-1700nm)has great potential in clinical theranostics,which is of great importance providing precise locations of lesions and molecular dynamic actions simultaneously in a single nanoprobe.Methods:T here has been an upsurge of multidisciplinary research focusing on developing functional types of inorganic and organic nanoprobes that can be used for NIR-II FL with the high spatiotemporal resolution,deep tissue penetration,and negligible auto-fluorescence.Results:In this mini-review,we summarize recent progress in inorganic/organic NIR-II FL nanoprobes.We introduce the design and properties of inorganic and organic nanoprobes,in the order of single-walled carbon nanotubes,quantum dots,rare-earth-doped nanoparticles,metal nanoclusters and organic fluorophores,expect to realize precise diagnosis and efficient image-guided therapy.Conclusion:Meanwhile,to elucidate the problems and perspectives,we aim to offer diverse biological applications of inorganic/organic NIR-II FL nanoprobes and accelerate the clinical transformation progress.

Near-infrared leaf reflectance modeling of Annona emarginata seedlings for early detection of variations in nitrogen concentration

Nitrogen(N)monitoring is essential in nurseries to ensure the production of high-quality seedlings.Nearinfrared spectroscopy(NIRS)is an instantaneous,nondestructive method to monitor N.Spectral data such as NIRS can also provide the basis for developing a new vegetation spectral index(VSI).Here,we evaluated whether NIRS combined with statistical modeling can accurately detect early variations in N concentration in leaves of young plants of Annona emargiaata and developed a new VSI for this task.Plants were grown in a hydroponics system with 0,2.75,5.5or 11 mM N for 45 days.Then we measured gas exchange,chlorophylla fluorescence,and pigments in leaves;analyzed complete leaf nutrients,and recorded spectral data for leaves at 966 to 1685 nm using NIRS.With a statistical learning approach,the dimensionality of the spectral data was reduced,then models were generated using two classes(N deficiency,N)or four classes(0,2.75,5.5,11 mM N).The best combination of techniques for dimensionality reduction and classification,respectively,was stepwise regression(PROC STEPDISC)and linear discriminant function.It was possible to detect N deficiency in seedlings leaves with 100%precision,and the four N concentrations with93.55%accuracy before photosynthetic damage to the plant occurred.Thereby,NIRS combined with statistical modeling of multidimensional data is effective for detecting N variations in seedlings leaves of A.emarginata.

Synthesis and Spectral Properties of Novel Water-soluble Near-infrared Fluorescent Indocyanines

Two fluorescent pentamethine and a squarylium indocyanines containing at least one p-carboxybenzyl group on N atoms in the heterocyclic rings were synthesized. They had good water solubility and photostability. Their maximum absorption and maximum emission were 600-700 nm in water. When it was anchored onto nanostructured TiO2 electrode, compared with in water, the squaraine showed double absorption peaks (one blue shifted and another red shifted) and absorption intensity of the red shift peak increased with the increase of the time of irradiation. The intensity of the blue one decreased simultaneously. We proposed that the presence of two electronic charge forms of squaraine anchored on the TiO2 film might be the reason.