Target Dye Research Articles

Preparation of a Novel Nanostructured Lead Titanate Composite Photocatalyst and Its Degradation of Organic Dyes under Visible Light

Photocatalytic dye degradation is an energy-saving, environmentally friendly and sustainable way of managing potentially toxic wastewater from the textile industry. PbTiO3 was prepared using a solid-state reaction method, and an optimal ratio of PbTiO3/TiO2/g-C3N4 photocatalyst was synthesized using the sol-gel method to test its ability to decompose organic dyes. Methylene blue (MB) was selected as a target dye to test the photocatalytic effects. SEM results showed that the synthesis of a PbTiO3/TiO2/g-C3N4 photocatalyst yielded a unique nano structure with many surface pores. UV-Vis analysis demonstrated that the novel composite photocatalyst had higher visible light absorption, and a reduced energy gap. Experimental results showed that of the samples tested, PTO/TO/CN 1.0 showed the best photocatalytic effect on the removal of MB. Under visible light, the removal rate of MB by PTO/TO/CN 1.0 was up to 98.79%. The novel PTO/TO/CN 1.0 photocatalyst exhibited relatively high MB adsorption and had a high photocatalytic ability.

Production of High Surface Area Activated Carbon from Peanut Shell by Chemical Activation with Zinc Chloride: Optimisation and Characterization

The potential of peanut shell as a precursor to produce activated carbon by chemical activation with ZnCl2, and the effect of activation variables were investigated using response surface methodology. Activation variables examined were temperature, hold time and impregnation ratio; among these, impregnation ratio and temperature were found to most affect the final characteristics of the produced activated carbon. The activation process was mapped, using design of experiments, and the optimum activation conditions were found to be a temperature of 485 °C, with a hold time of 15 min and an impregnation ratio of 1.7. Under the optimised conditions, an activated carbon with a relatively high surface area of ~ 1700 m2/g was produced, at a yield of 47%. Moreover, the carbon exhibited a relatively high density, ranging from 1.455 g/cm3 to 1.750 g/cm3, as well as a low ash content below 1% and a high fixed carbon content above 86%. SEM analysis and FTIR characterisation revealed the heterogenous nature of the produced carbon materials. The developed materials, with potential as adsorbents, removed up to 99.8% of a target dye (methyl orange) depending on their available surface area. Hence, through the insights gained, an optimised carbon is produced, demonstrating the potential to tailor activated carbon materials produced from waste biomass.

Characterizing azobenzene disperse dyes and related compounds in house dust and their correlations with other organic contaminant classes

Azobenzene disperse dyes are the fastest-growing category of commercial dyestuffs and are implicated in the literature as potentially allergenic. In the indoor environment, these dyes may be shed from various textiles, including clothing and upholstery and accumulate in dust particles potentially leading to exposure in young children who have higher exposure to chemicals associated with dust due to their crawling and mouthing behaviors. Children may be more vulnerable to dye exposure due to their developing immune systems, and therefore, it is critical to characterize azobenzene disperse dyes in children's home environments. Here, we investigate azobenzene disperse dyes and related compounds in house dust samples (n = 124) that were previously analyzed for flame retardants, phthalates, pesticides and per- and polyfluoroalkyl substances (PFAS). High-resolution mass spectrometry was used to support both targeted and suspect screening of dyes in dust. Statistical analyses were conducted to determine if dye concentrations were related to demographic information. Detection frequencies for 12 target dyes ranged from 11% to 89%; of the dyes that were detected in at least 50% of the samples, geometric mean levels ranged from 32.4 to 360 ng/g. Suspect screening analysis identified eight additional high-abundance azobenzene compounds in dust. Some dyes were correlated to numerous flame retardants and several antimicrobials, and statistically higher levels of some dyes were observed in homes of non-Hispanic Black mothers than in homes of non-Hispanic white mothers. To our knowledge, this is the most comprehensive study of azobenzene disperse dyes in house dust to date. Future studies are needed to quantify additional dyes in dust and to examine exposure pathways of dyes in indoor environments where children are concerned.

Azadirachta indica-assisted green synthesis of magnesium oxide nanoparticles for degradation of Reactive Red 195 dye: a sustainable environmental remedial approach

A variety of industries employ synthetic azo dyes. However, the biosphere is being damaged by the unused/leftover azo dyes, which pose a danger to all living things. Therefore, treating them to shield the environment from the potential harm of azo dyes is crucial. Bio-sorption is a cheap and effective mode for eliminating toxic dyes in the environment. The current work focused on synthesizing magnesium oxide (MgO) nanoparticles using an aqueous leaf extract of neem (Azadirachta indica). The XRD and SEM analyses of MgO nanoparticles indicated the crystalline nature of MgO nanoparticles with a cubic structure, and the size was around 90–100 nm. FTIR analysis showed the presence of a stretching frequency peak at 550 cm−1, confirming the Mg–O bond. The surface analysis revealed the cluster form of the synthesized nanoparticles. The UV–visible absorption peak for MgO nanoparticles was found at 294 nm and band gap of 4.52 eV. In order to eliminate the Reactive Red 195 dye, MgO nanoparticles were used. At pH 4, 40 °C, 0.02% dye concentration, and 0.003 g/L catalyst amount, the highest degree of decolorization (91%) was seen. Decreased total organic carbon (TOC) and the chemical oxygen demand (COD) percent were 84.33% and 81.3%, respectively. The proposed mechanism of target dye degradation was also investigated. MgO NPs were found to be effective in their catalytic behavior toward the degradation of Reactive Red 195 dye up to five cycles with almost no change in their catalytic activity.

Comparison between NiO and MnO2 nanoparticles deposited on graphene-coated nickel foam for water purification applications

Nanoparticles of NiO, and MnO2 nanoparticles were successfully synthesized on graphene-coated Nickel foam (NFG) substrates for the synthesis of dual-functional specimens for antibacterial and photocatalytic applications. The morphological, structural, and optical properties were investigated thanks to the techniques of scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV–Vis, and photoluminescence spectroscopy. It was observed from XRD analysis that α-MnO2 and NiO nanoparticles were deposited with high purity as a thin film on NFG substrates. The photocatalytic efficiency of the synthesized materials was tested on a Methylene blue (MB) solution as a target dye pollutant and the obtained results indicate a good degradation rate under visible light irradiation. Antibacterial activity was tested on Staph aureus, Pseudomonas aeruginosa, and the yeast Candida albicans. The obtained results show that MnO2/NFG and NiO/NFG specimens constitute good candidates for the treatment of wastewater.

Photoelectrocatalytic Detection and Degradation Studies of a Hazardous Textile Dye Safranin T.

Herein, we report an electrochemical scaffold consisting of functionalized multiwalled carbon nanotubes (COOH-fMWCNTs) and iron-doped zinc oxide nanoparticles (Fe-ZnO) for the detection of a hazardous textile dye safranin T (ST) and monitoring of its photocatalytic degradation. Prior to the detection and degradation analysis, Fe-ZnO NPs were synthesized by the sol-gel method and characterized by a number of structural and morphological techniques. The carboxyl moiety of COOH-fMWCNTs possessing a strong affinity for the amino functionality of ST led to significant enhancement of the current response at the designed electrochemical platform, whereas the electrocatalytic role, surface area enhancement, and the provision of binding sites of Fe-ZnO led to a further increase in the peak current intensity of ST. Electrochemical impedance spectroscopy showed that the sensing scaffold made of the glassy carbon electrode modified with COOH-fMWCNTs and Fe-ZnO efficiently transfers charge between the transducer and the redox probe. Under optimized conditions, the developed sensor showed a 2.3 nM limit of detection for ST. Moreover, recovery experiments and anti-interference tests qualified the sensing platform for practical applications. The dye was photocatalytically degraded using Fe-ZnO NPs up to 99% in 60 min with a rate constant of 0.068 min-1. The designed sensor was used to probe the degradation kinetics of the target dye, and the results were found consistent with the findings obtained from electronic absorption method. To the best of our knowledge, the present work is the first approach for the efficient detection and almost absolute degradation of ST.

The study on the use of a biocatalyst based on Calcined Cow Teeth-TiO2 composite in degrading the methylene blue dye

Cow teeth are a type of natural biomaterial exhibiting a unique hierarchical porous structure that has not been widely studied in catalysis. In this work, from a simple deposition and calcination process, a Cow Teeth composite CCT-TiO2 was fabricated using Calcined Cow Teeth as a template and employed as a biocatalyst to remove a specific target dye from an aqueous solution under UV irradiation.The composite, CCT-TiO2, with a dosage of (0.2 g/L), at room temperature and a 3 h treatment time under UV light, showed a positive behavior towards the photochemical degradation of Methylene Blue (C = 0.01 g/L) mainly in a basic medium pH = 8 giving a catalytic efficiency rate up to 98%.The main parameters affecting the efficiency of the photocatalytic treatment, such as pH, the mass of catalyst added to the solution, the percentage of TiO2 in the composite, the concentration of MB at the beginning, the presence of ethanol, the addition of hydrogen peroxide and the temperature were studied to evaluate their influence on the degradation of methylene blue.The photodegradation performance is inversely proportional to the initial dye concentration. Similarly, for the temperature, the higher the temperature, the higher the photodegradation performance (removal rate 57% for a temperature of 55 °C). However, the presence of ethanol in the solution has a negative impact on the oxidation process, with a yield of 56% after 4 h30 min of treatment under UV irradiation. On the other side, the addition of oxygenated water considerably improves the photodegradation performances of methylene blue, with an efficiency of dye removal going up to 87% after 1 h of treatment.The excellent catalytic degradation performance and low cost suggest that this process has significant potential for effectively treating industrial wastewater loaded with cationic dye.

Study on Adsorption and Photocatalytic Properties of Zinc Ferrite

In this study, methyl orange, methylene blue, and amido black 10B were removed as target dyes using purified, synthetic, and purchased zinc ferrite as adsorbents and photocatalysts. The highest removal rates of amido black 10B by these adsorbents ranged from 81.62% to 88.33%. The removal rate of methyl orange was approximately 1%, and the removal rate of methylene blue was approximately 2%. Hence, an investigation was conducted to elucidate the factors that influence the removal efficacy of purified zinc ferrite on amido black 10B. Titanium dioxide prepared at different calcination temperatures was unsuccessful in removing amido black 10B, but the physical mixing of titanium dioxide prepared at suitable calcination temperatures with purified zinc ferrite had a positive effect on amido black 10B removal. Since zinc ferrite could not be used as an adsorbent to remove methyl orange and methylene blue, the photocatalytic degradation properties of zinc ferrite and its influencing factors were studied. The optimal conditions for the photocatalytic degradation of methylene blue and methyl orange by zinc ferrite are as follows: a zinc ferrite catalyst dosage of 0.15 g, an initial solution concentration of 20 mg/L, and a pH of 6.0. The dosage of the zinc ferrite/titanium dioxide composite catalyst is 0.15 g, the initial solution concentration is 20 mg/L, and the pH is 6.5.

Preclinical biocompatibility and biosafety evaluation of a new foldable brown diaphragm intraocular lens: An in vitro and in vivo study.

A new foldable brown diaphragm intraocular lens (IOL) was preclinically evaluated in vitro and in vivo by comparing its biocompatibility and biosafety with those of a commercially available IOL. The new foldable iris-diaphragm IOL is composed of hydrophobic acrylic material, with a transparent optical zone and surrounding brown diaphragm. Cellular experiments evaluating lens epithelial cell morphology, adhesion, and migration were conducted to exclude cytotoxic effects. Twelve New Zealand rabbits underwent implantation of a brown diaphragm IOL in one eye, whilst an additional 12 had a commercially available foldable IOL implanted, followed by slit-lamp evaluations of inflammatory reactions and capsular opacification. Corneal endothelial cells density was measured before and after implantation. Aqueous humour samples were obtained weekly for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to investigate dye leakage from the brown-diaphragm IOL. Following 12 weeks of observation, haematoxylin and eosin staining of ocular tissue and scanning electron microscopy (SEM) of the IOL surface were performed. Results from in vivo experiments found no statistically significant differences between the two groups in terms of postoperative inflammation and capsular biocompatibility. No significant changes in corneal endothelial cell density were observed in either group before and after surgery. LC-MS/MS analysis showed that the target dye was not detected in aqueous humour samples. Histopathology of ocular sections and SEM imaging of IOL surfaces showed similar changes in both groups. The newly invented IOL showed good biocompatibility and biosafety. Combined with its foldability and peripheral shading, it could be a new choice for patients with iris defects.

Enhancing methyl orange adsorption capacity via functionalizing ZIF-8 with amphiphilic cetylpyridinium bromide

BackgroundThe precise design or functionalization of metal organic frameworks (MOFs) based on the properties of organic dyes is a promising direction in environment remediation. MethodsHerein, using methyl orange (MO) as the target dye, cetylpyridinium bromide (CPB) functionalized ZIF-8 (CPB@ZIF-8) was fabricated by the post-synthetic modification strategy. Significant findingsThe surface area and the pore volume of CPB@ZIF-8 are greatly reduced compared with pure ZIF-8. However, the introduction of amphiphilic CPB molecules into ZIF-8 can significantly enhance the adsorption performance of MO. This enhanced MO adsorption capacity can be attributed to the incorporation of more positively charged sites, hydrophobic sites and aromatic rings in the CPB-modified ZIF-8 frameworks, which provides the electrostatic attractions, the hydrophobic and π-π interactions that mainly govern the adsorption of MO on CPB@ZIF-8. The pseudo-second-order kinetic model and the Langmuir isotherm model can well represent the adsorption process of MO. The maximum adsorption capacity (195.54 mg/g) has been obtained at 30 °C, outperforming pristine ZIF-8 and various reported absorbents. The prepared CPB@ZIF-8 composite is a superior example of the tunable adsorption affinity of MOFs for anionic dyes.

Nonlinear optical properties and transient absorption in Hibiscus Sabdariffa dye solution probed with femtosecond pulses

Highly conjugated organic molecules are attractive chromophores for nonlinear optics due to their significant third-order nonlinear response near the absorption bands located in the broad spectral range from 200 to 900 nm. In this work, we report on the wavelength-dependence of one- and two-photon absorption processes in Hibiscus sabdariffa organic dye excited by femtosecond (fs) laser pulses centered at 1030 nm and 515 nm. Z-scan and transient absorption (TA) techniques have been employed to investigate the absorption and relaxation processes in the target dye. The dye is found to have a significant negative nonlinear absorption coefficient (β) of value ∼ −2.7 × 10−11 cm/W at 515 nm probing laser pulses, while it has a positive value equal to +2.1 × 10−13 cm/W when 1030 nm laser pulses were employed. The TA decay measurements using 40 fs laser pulses, centered at 515 nm wavelength, reveal that the dye exhibits a short relaxation time of ∼3 ps attributed to the involvement of the excited state proton transfer (ESPT) process in the Hibiscus dye solution. Moreover, our time-integrated fluorescence measurements revealed that no fluorescence emission could be detected. The application of ultrashort pulses of ∼40 fs duration enabled the tracking of ESPT in the Hibiscus dye, which was not detected in previous studies that employed laser pulses of picoseconds and nanoseconds duration.

Plant-assisted synthesis and characterization of MnO2 nanoparticles for removal of crystal violet dye: an environmental remedial approach.

The current study is focused on the use of the Caryota mitis Lour. (Fishtail palm) flower extract as a reducing agent for the preparation of manganese dioxide (MnO2) nanoparticles. Scanning electron microscopy (SEM), four-phase infrared analysis (FT-IR), and x-ray diffraction (XRD) methods were used to characterize the MnO2 nanoparticles. The nature of MnO2 nanoparticles was revealed by an absorption peak at 590nm in a spectrophotometer (A1000). Then, these MnO2 nanoparticles were applied to decolorize the crystal violet dye. At 0.004% dye concentration, pH 4, and concentration of MnO2 nanoparticles of 0.005g/L at temperatures of 50°C, the target dye was decolorized by 91.3%. Percent reductions in COD and TOC were found to be 92.1% and 90.6%, respectively. Finally, the dye decolorization pathway was proposed based on the experimental findings.

Aqueous biphasic systems composed of alcohol-based deep eutectic solvents and inorganic salts: Application in the extraction of dyes with varying hydrophobicity

The scientific community discovered green solvents for the preconcentration and separation of various target compounds owing to challenges posed by the earliest solvents. Among these neoteric solvents are deep eutectic solvents (DESs). They have been termed “21st-century solvents” due to their distinct characteristic properties like low toxicity, high tuneability, high biodegradability, cheap nature, ease of preparation, etc. In this study, six novel DESs were synthesized from benzyltrimethylammonium chloride (BTMAC), benzyltrimethylammonium chloride (BTEAC) as hydrogen bond acceptors (HBAs), methanol (MEOH), ethanol (ETOH) and propanol (PROH) as hydrogen bond donors (HBDs) at 1:3 molar ratio. The prepared DESs were employed for the development of aqueous biphasic systems (ABSs) in combination with Na2CO3, K3PO4, K2HPO4, and K2CO3 at 298.15 K and atmospheric pressure. The salting out ability of the salts investigated follows the decreasing order: Na2CO3 > K3PO4 > K2HPO4 ≈ K2CO3. The DES based extraction platforms were applied for the partitioning of Alizarin red S (ARS), Orange II (OII), and Congo red (CR). In all the studied ABSs, the partition coefficients (Kdyes), and extraction efficiencies (%EEdyes) for the target dyes followed the sequence: CR > OII > ARS. The obtained trend was attributed to log Kow and structural differences of the investigated dyes (i.e. presence of different aromatic groups). The proposed ABSs of DES have great potential for removing various dyes completely from aqueous media.

Synthesis of Fe-doped ZnO by supercritical antisolvent precipitation for the degradation of azo dyes under visible light

Supercritical antisolvent precipitation was used to obtain ZnO (undoped) and Fe-doped ZnO photocatalysts at different Fe/Zn molar ratio percentages (0.57, 0.75 and 0.84 mol%). Wide-angle X-ray diffraction showed the hexagonal wurtzite as the main crystalline phase of the cauliflower-like nanoparticle aggregations (observed from Field Emission Scanning Electron Microscopy) with a mean diameter of 54.5 nm for the pure ZnO nanoparticles and a higher mean diameter (in the range 109.1–121.5 nm) for Fe-doped ZnO nanoparticles. XRF confirmed the approximate Fe/Zn ratios (0.55, 0.77, 0.82 mol%). The band gap energy, derived from UV − Vis diffuse reflectance measurements decreased upon Fe doping with values ranging from 3.22 (ZnO) to 2.83 eV (0.57 mol%Fe). The photocatalytic activity results showed that the undoped ZnO photocatalyst completely removes color from an aqueous solution containing Acid Orange 7 dye (AO7) after 30 min of UV light irradiation. Whereas Fe-doped ZnO photocatalyst with 0.75 mol% Fe content (0.75Fe) exhibited the highest discoloration efficiency (52 %) and total organic carbon (TOC) removal efficiency (∼36 %) of AO7 after 180 min under visible light. Moreover, the main reactive oxygen species involved in the AO7 degradation were assessed with the optimized photocatalyst (0.75Fe) in presence of scavenger molecules. The experimental results revealed that positive holes and superoxide are responsible for target dye degradation under visible light.

Long-term photochemical stability of heteroaromatic dye-functionalised g-C3N4via covalent linkage for efficient photocatalytic hydrogen evolution

In this study, three typical D–π–A type heteroaromatic organic dyes containing carbazole (CBZ), phenothiazine (PTZ), and phenoxazine (POZ) moiety as electron donor cores and linked to g-C3N4 with amide covalent bonds were synthesized. Thereafter, we studied the long-term photochemical stability and degradation mechanism of the associated dye-sensitised g-C3N4 with covalent linkage or weak interaction. The results revealed that most of the dyes degraded and became unstable after absorption on g-C3N4 under light irradiation. Interestingly, after the target dyes were linked to g-C3N4 with amide covalent bonds, the photostability could be effectively promoted and improved to high levels of stability. For POZ-S dye covalent bond-linked sample g-C3N4/POZ-S, ∼90.5% percent of the dyes were reserved, whereas only ∼25.3% remained for the physically absorbed dye sample g-C3N4+POZ-S after 30 min of irradiation aging test. Moreover, the obtained g-C3N4/POZ-S sample exhibited enhanced H2 evolution activity with photocatalytic H2 production rates that were approximately 96- fold of that of pure g-C3N4. Then, we applied various instrumental analysis and DFT calculation to clarify the mechanism involved with dye photostability and degradation pathway. The typical decarboxylation process was confirmed, and such an unfavourable reaction process could be effectively inhibited if the target dye is linked to g-C3N4 with amide covalent bond instead of the weak interaction. Overall, the existed covalent bond is the key factor for enhancing both the photochemical stability and photocatalytic activity of organic dye-sensitised g-C3N4 for hydrogen evolution.

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol-Gel Method.

A reverse-micelle sol-gel method was chosen for the preparation of Fe-doped TiO2 samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst composition towards the target dye degradation. The photocatalysts were characterized through a multi-technique approach, envisaging XRPD and QPA as obtained by Rietveld refinement, FE-SEM analysis, DR UV-vis spectroscopy, N2 adsorption/desorption isotherms measurement at -196 °C, ζ-potential measurement, and XPS analysis. The physical-chemical characterization showed that the adopted synthesis method allows obtaining NPs with uniform shape and size and promotes the introduction of Fe into the titania matrix, finally affecting the relative amounts of the three occurring polymorphs of TiO2 (anatase, rutile and brookite). By increasing the Fe content, the band gap energy decreases from 3.13 eV (with undoped TiO2) to 2.65 eV (with both 2.5 and 3.5 wt.% nominal Fe contents). At higher Fe content, surface Fe oxo-hydroxide species occur, as shown by DR UV-vis and XP spectroscopies. All the Fe-doped TiO2 photocatalysts were active in the degradation and mineralization of the target dye, showing a TOC removal higher than the undoped sample. The photoactivity under visible light was ascribed both to the band-gap reduction (as confirmed by phenol photodegradation) and to dye sensitization of the photocatalyst surface (as confirmed by photocatalytic tests carried out using different visible-emission spectra LEDs). The main reactive species involved in the dye degradation were determined to be positive holes.

Selective synthesis of clamshell-type bis-phthalocyanine bearing tetrachlorocyclotriphosphazene intramolecular bridge

The selective synthesis of clamshell-type bis-phthalocyanine was performed using cyclotriphosphazene as a peripheral spacer. The spectral characteristics of the target dye are similar to those of most H-dimers, and the reaction can be considered conditionally selective with respect to the cis-isomer

Interface synthesis of Cu-BTC/PVDF hybrid membranes and their selective adsorption activity toward Congo red.

Considering the surface affinity of MOFs and separation advantages of polymer membranes, herein, a one-step interface synthesis strategy is used in the construction of Cu-BTC/PVDF hybrid membranes, in which Cu2+ ions and 1,3,5-benzenetricarboxylic acid (H3BTC) were dissolved in ionized water and n-octanol separately, and polyvinylidene fluoride (PVDF) films were laid at the interface of two immiscible solvents. As a result, Cu-BTC was generated and readily self-assembled inside the PVDF films. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method were used to characterize Cu-BTC/PVDF hybrid membranes, and Congo red (CR) was selected as the target dye to evaluate the surface adsorption activity of the hybrid membranes. Batch adsorption tests under various conditions were conducted to optimize the adsorption capacity, adsorption kinetics, isotherms and thermodynamics, which were analyzed to further explore the adsorption behavior. Based on this, the adsorption mechanism was discussed. It is worth noting that because of the π-π stacking interaction and hydrogen bonding, an extraordinary adsorption capacity of CR was achieved, and the good separation advantage and the cyclic adsorption performances endow the resulting Cu-BTC/PVDF hybrid membranes with promising applications in the removal of organic dyes from practical wastewater.

Mitochondria-targeted fluorophores for in vivo NIR-II imaging-guided PDT/PTT.

A simple yet powerful D-A type-based NIR-II fluorophore (MTF) with mitochondria targeting was constructed. This mitochondrial targeting dye MTF exhibited not only a photothermal effect but also photodynamic performance, and was further fabricated with DSPE-mPEG to generate nanodots for in vivo experiments, achieving strong NIR-II fluorescence tracing of tumors and impressive NIR-II image-guided photodynamic therapy (PDT) and photothermal therapy (PTT).

Experimentally Calibrated Computational Prediction Enables Accurate Fine-Tuning of Near-Infrared Rhodamines for Multiplexing.

A significant barrier inhibiting multiplexed imaging in the near-infrared (NIR) is the extensive trial and error associated with fine-tuning NIR dyes. In particular, the need to synthesize and experimentally evaluate dye derivatives in order to empirically identify those that can be used in multiplexing applications, requires a large investment of time. While coarse-tuning efforts benefit from computational prediction that can be used to identify target dye structures for synthetic campaigns, errors in computational prediction remain too large to accurately parse modifications aimed at fine-tuning changes in dye absorbance and emission. To address this issue, we screened different levels of theory and identified a time-dependent density functional theory (TD-DFT) approach that can rapidly, as opposed to synthesis and experimental evaluation, estimate absorbance and emission. By calibrating these computational estimations of absorbance and emission to experimentally determined parameters for a panel of existing NIR dyes, we obtain calibration curves that can be used to accurately predict the effect of fine-tuning modifications in new dyes. We demonstrate the predictive power of this calibrated dataset using seven previously unreported dyes, obtaining mean percent errors in absorbance and emission of 2.2 and 2.8 %, respectively. This approach provides a significant timesavings, relative to synthesis and evaluation of dye derivatives, and can be used to focus synthetic campaigns on the most promising dye structures. The new dyes described herein can be utilized for multiplexed imaging, and the experimentally calibrated dataset will provide the dye chemistry community with a means to rapidly identify fine-tuned NIR dyes in silico to guide subsequent synthetic campaigns.