Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes

Highly Efficient DSSCs Sensitized Using NIR Responsive Bacteriopheophytine-a and Its Derivatives Extracted from Rhodobacter Sphaeroides Photobacteria

Employing naturally extracted dyes and their derivatives as photosensitizers towards the construction of dye-sensitized solar cells (DSSCs) has been recently emerging for establishing sustainable energy conversion devices. In this present work, Rhodobacter Sphaeroides Photobacteria (Rh. Sphaeroides) was used as a natural source from which Bacteriopheophytine-a (Bhcl) dye was extracted. Further, two cationic derivatives of Bhcl, viz., Guanidino-bacteriopheophorbide-a (Gua-Bhcl) and (2-aminoethyl)triphenylphosphono-bacteriopheophorbide-a (2AETPPh-Bhcl) were synthesized. The thus obtained Bhcl, Gua-Bhcl and 2AETPPh-Bhcl were characterized using liquid chromatography-mass spectrometry (LC-MS) and their photophysical properties were investigated using excitation and emission studies. All three near-infrared (NIR) responsive dyes were employed as natural sensitizers towards the construction of DSSC devices, using platinum as a photocathode, dye-sensitized P25-TiO2 as a photoanode and I-/I3- as an electrolyte. DSSCs fabricated using all three dyes have shown reasonably good photovoltaic performance, among which 2AETPPh-Bhcl dye has shown a relatively higher power conversion efficiency (η) of 0.38% with a short circuit photocurrent density (JSC) of 1.03 mA cm-2. This could be attributed to the dye's natural optimal light absorption in the visible and NIR region and uniform dispersion through the electrostatic interaction of the cationic derivatives on the TiO2 photoanode. Furthermore, the atomic force microscopy studies and electrochemical investigations using cyclic voltammetry, electrochemical impedance spectroscopy and Bode's plot also supported the enhancement in performance attained with 2AETPPh-Bhcl dye.

Phytoferritin functions in two interface-loading of natural pigment betanin and caffeic acid with enhanced color stability and the sustained release of betanin

Betanin, a natural red pigment, is sensitive and prone to fading and discoloration, affecting its stability and bioavailability. Phytoferritin is a nano-diameter protein with unique interior-/exterior-interfaces. By the unique interfaces and pH-induced self-assembly of ferritin, a ferritin-betanin complex (FB) with an encapsulation efficiency of 17.66 ± 1.24% was prepared. The caffeic acid-FB (CFB) was further fabricated by attaching ferritin with caffeic acid, and the binding number n of caffeic acid was 88.47 ± 9.49, with a binding constant K of (1.63 ± 0.33) × 104 M-1. Fluorescence and Fourier transform infrared analysis indicated that the encapsulation of betanin and the binding of caffeic acid influenced the ferritin structure. The interaction between caffeic acid and ferritin was mainly through van der Waals forces and hydrogen bonds. TEM and DLS showed that the globular structure and diameter (12 nm) remained in CFB. Furthermore, the ferritin and caffeic acid exhibited a synergistic effect in enhancing thermal, light, and ferric ion stabilities, and controlled the betanin release in a more sustained manner in the simulated gastrointestinal tract. In addition, the antioxidant capacity of CFB was enhanced compared with free betanin. This study promotes the bioavailability of betanin by two interface-loading of ferritin, and guides the use of ferritin nanoparticles as a nanocarrier for pigment stabilization.

Natural sensitizer extracted from Mussaenda erythrophylla for dye-sensitized solar cell

In this study, a natural dye from the flowers of Mussaenda erythrophylla extracted separately in ethanol and de-ionized water was employed as a photosensitizer in DSSCs. The quantitative phytochemical analyses were performed on both extracts. The existence of flavonoids (anthocyanin) and chlorophyll a pigments in the ethanol extract of the dye was confirmed by the UV-Visible spectroscopy. The stability study performed on the said ethanol extract confirmed that the dye extracted in ethanol was stable in the dark and did not degrade for nearly 50 days. The presence of the dye molecules and uniform adsorption of them on the P25-TiO2 surface were confirmed by fourier transform infrared spectroscopy and atomic force microscopy, respectively. Moreover, the influence of dye concentration and pH on the optical properties of the dye was also studied. The natural dye extracted in ethanol was employed in DSSCs, fabricated by utilizing the said dye sensitized P25-TiO2 photoanodes, [Formula: see text]/[Formula: see text] electrolyte, and Pt counter electrode. Photovoltaic performances of the fabricated devices were determined under simulated irradiation with the intensity of 100 mWcm-2 using AM 1.5 filter. The device fabricated with the P25-TiO2 photoanode sensitized by the dye extracted in ethanol at pH = 5 exhibited the best power conversion efficiency (PCE) of 0.41% with the JSC of 0.98 mAcm-2 which could be attributed to the optimum light absorption in the visible region of solar spectrum by the chlorophyll a and anthocyanin molecules in the extracted natural dye.

Betalains as promising natural colorants in smart/active food packaging

Betalains are water-soluble nitrogen pigments with beneficial effects, including antioxidant, antimicrobial, and pH-indicator properties. The development of packaging films incorporated with betalains has received increasing attention because of pH-responsive color-changing properties in the colorimetric indicators and smart packaging films. As such, intelligent and active packaging systems based on biodegradable polymers containing betalains have been recently developed as eco-friendly packaging to enhance the quality and safety of food products. Betalains could generally improve the functional properties of packaging films, such as higher water resistance, tensile strength, elongation at break, and antioxidant and antimicrobial activities. These effects are dependent on betalain composition (about its source and extraction), content, and the kind of biopolymer, film preparation method, food samples, and storage time. This review focused on betalains-rich films as pH- and ammonia-sensitive indicators and their applications as smart packaging to monitor the freshness of protein-rich foods such as shrimp, fish, chicken, and milk.

Microencapsulated and Ready-to-Eat Beetroot Soup: A Stable and Attractive Formulation Enriched in Nitrate, Betalains and Minerals

Beetroot is a tuber rich in antioxidant compounds, i.e., betanin and saponins, and is one of the main sources of dietary nitrate. The aim of the present study was to microencapsulate a ready-to-eat beetroot soup by lyophilization using different encapsulating agents, which supply the required amount of bioactive nutrients. Particle size distributions ranged from 7.94 ± 1.74 to 245.66 ± 2.31 µm for beetroot soup in starch and from 30.56 ± 1.66 to 636.34 ± 2.04 µm in maltodextrin. Microparticle yields of powdered beetroot soup in starch varied from 77.68% to 88.91%, and in maltodextrin from 75.01% to 80.25%. The NO3− and total betalain contents at a 1:2 ratio were 10.46 ± 0.22 mmol·100 g−1 fresh weight basis and 219.7 ± 4.92 mg·g−1 in starch powdered beetroot soup and 8.43 ± 0.09 mmol·100 g−1 fresh weight basis and 223.9 ± 4.21 mg·g−1 in maltodextrin powdered beetroot soup. Six distinct minerals were identified and quantified in beetroot soups, namely Na, K, Mg, Mn, Zn and P. Beetroot soup microencapsulated in starch or maltodextrin complied with microbiological quality guidelines for consumption, with good acceptance and purchase intention throughout 90 days of storage. Microencapsulated beetroot soup may, thus, comprise a novel attractive strategy to offer high contents of bioaccessible dietary nitrate and antioxidant compounds that may aid in the improvement of vascular-protective effects.

Mechanistic insights into UV photolysis of carbamazepine and caffeine: Active species, reaction sites, and toxicity evolution

The pseudo-persistence of pharmaceutical and personal care products (PPCPs)in the aqueous environment may pose potential risks to human health and ecosystems. The UV disinfection in wastewater treatment plants is one of the essential processes before PPCPs enter the water environment, so it is crucial to elucidate the photolytic behavior and mechanism of PPCPs under UV radiation. In this work, carbamazepine (CBZ) and caffeine (CAF) were selected as typical pollutants to investigate the effect of water matrixes, humic acid, inorganic ions, and pH on the UV radiation performance. Hydroxyl radical (•OH) and singlet oxygen (¹O₂) were identified by quenching experiments and electron paramagnetic resonance (EPR) spectra as playing a dominant role in the degradation process. UPLC-TOF/MS was conducted to identify 13 and 14 possible intermediates of CBZ and CAF, respectively. Moreover, combining density functional theory (DFT) calculations (Frontier Molecular Orbital and Fukui index), hydroxylation, oxidation, and ring cleavage were proposed as the main degradation pathways of the contaminants, which occurred first at the C(7C), N(17 N) and O(18O) sites of CBZ and at the C(9C) site of CAF. The bio-acute toxicity experiment and the Ecological Structure-Activity Relationships (ECOSAR) program were performed to analyze and predict the toxicity of the intermediates of CBZ and CAF under UV radiation, respectively. The results showed that the acute toxicity of both solutions increased after UV radiation and followed with the combined toxicity. This work has great scientific value and practical environmental significance for evaluating the UV disinfection process and managing PPCPs in the aqueous environment.

FT-IR Analysis of Beta vulgaris Peels and Pomace Dye Extracts and Surface Analysis of Optimally Dyed-Mordanted Cellulosic Fabrics

FT-IR spectroscopy is a nondestructive technique that can be utilized for the qualitative characterization of natural dyes and dyed substrates through structure elucidation. This work aimed at the characterization of natural dye extract from Beta vulgaris peels and pomaces and surface analysis of optimally dyed-mordanted cotton (cellulosic) fabric using Fourier Transform Infrared (FT-IR) spectroscopy, as well as colour fastness tests (light, washing, rubbing, and perspiration). Response surface methodology (RSM) was employed in the optimization of dyeing temperature (T), time (t), and pH, as well as applying the relative percent change in colour strength (ΔE) of dyed fabrics as the response. The natural mordants (tannic acid-alum) were compared with synthetic mordants (K2Cr2O7, FeSO4, and CuSO4) using the three mordanting methods. The optimized dyeing parameters were T (55°C), t (75 minutes), and pH (6.5), as a result of comparatively high relative % ΔE (11%). The FT-IR analysis of the extract revealed different characteristic absorption peak values for various functional groups: 3282.82 cm−1 (–OH stretch), 2932.96 cm−1 (C–H stretch), and 1588.91 cm−1 (C=N stretch), among others. The C=N bond stretch biomarks the presence of nitrogen-containing compounds such as the reddish betanin pigments. $p>0.05$ of the dyeing parameters implied that they are not significant but affect dyeing probably alongside other factors such as mordanting. The spectral analysis of bleached and optimally dyed (nonmordanted and mordanted) fabrics revealed varied peaks indicating different functional groups suggesting the presence of cellulose and the binding of mordants with chromophores in the dye extract which yield different shades. Postmordanting showed mean ratings of 4-5 (excellent) among all fastness tests, displayed by tannic acid-alum, FeSO4, and CuSO4. Generally, mordanting resulted in enhanced dye stability and improved colour fastness. To identify specific chromophores in dye extracts and their molecular configurations due to mordants, advanced FT-IR hyphenated systems can be employed.

Influence of Fermentation Beetroot Juice Process on the Physico-Chemical Properties of Spray Dried Powder

Picking vegetables is, along with salting and drying, one of the oldest ways to preserve food in the world. This is the process of decomposition of simple sugars into lactic acid with the participation of lactic bacteria. The aim of the study was to obtain powders from fermented red beet juice with the highest possible amount of lactic acid bacteria (LAB) and active ingredients. For the analysis, juices were squeezed from the vegetables and two types of fermentation were used: a spontaneous fermentation and a dedicated one. After inoculation, samples were taken for analysis on a daily basis. Extract, pH, total acidity, pigments, and color were measured. In addition, microbiological tests were also carried out. The juices from the fifth day of fermentation was also spray dried, to obtain fermented beetroot powder. Juices from 3–5th day were characterized by a high content of LAB and betanin, had also a low pH, which proves that the lactic fermentation is working properly. The exception was the juice from spontaneous fermentation. According to the observations, the fermentation process did not run properly, and further analysis is needed. The powders were stable; however, results obtained from the pigment content and the LAB content are not satisfactory and require further analysis.

Beta vulgaris Assisted Fabrication of Novel Ag-Cu Bimetallic Nanoparticles for Growth Inhibition and Virulence in Candida albicans

Beta vulgaris extract contains water-soluble red pigment betanin and is used as a food colorant. In this study, the biogenic Ag-Cu bimetallic nanoparticles were synthesized and characterized by different spectroscopic and microscopic techniques, including UV-Visible, FTIR, TEM. SEM-EDX, XRD, and TGA. Further, Ag-Cu bimetallic nanoparticles capped with Beta vulgaris biomolecules were evaluated for their antifungal activity against Candida albicans via targeting its major virulence factors, including adherence, yeast to hyphae transition, extracellular enzyme secretion, biofilm formation, and the expression of genes related to these pathogenic traits by using standard methods. C. albicans is an opportunistic human fungal pathogen that causes significant morbidity and mortality, mainly in immunocompromised patients. The current antifungal therapy is limited with various shortcomings such as host toxicity and developing multidrug resistance. Therefore, the development of novel antifungal agents is urgently required. Furthermore, NPs were screened for cell viability and cytotoxicity effect. Antifungal susceptibility testing showed potent antifungal activity of the Ag-Cu bimetallic NPs with a significant inhibitory effect on adherence, yeast to hyphae transition, extracellular enzymes secretion, and formation of biofilms in C. albicans at sub-inhibitory and inhibitory concentrations. The RT-qPCR results at an MIC value of the NPs exhibited a varying degree of downregulation in expression levels of virulence genes. Results also revealed the dose-dependent effect of NPs on cellular viability (up to 100%) using MUSE cell analyzer. Moreover, the low cytotoxicity effect of bimetallic NPs has been observed using haemolytic assay. The overall results indicated that the newly synthesized Ag-Cu bimetallic NPs capped with Beta vulgaris are proven to possess a potent anticandidal activity, by affecting the vital pathogenic factors of C. albicans.

A Study On the Optoelectronic Parameters of Natural Dyes Extracted from Beetroot, Cabbage, Walnut, and Henna for Potential Applications in Organic Electronics

In this work, the optoelectronic parameters of natural dyes extracted from beetroot, red cabbage, walnut leaves, and henna were comprehensively investigated, namely the optical energy gap (E_g), extinction coefficient (k), refractive index (n), dielectric constant ([Formula: see text], and optical conductivity ([Formula: see text]. Results showed a high refractive index, dielectric constant and optical conductivity ([Formula: see text] and [Formula: see text]) for the dye extracted from red cabbage, while minimum values of [Formula: see text] and [Formula: see text] were obtained for the henna dye. The transition type of the optical absorption of the dyes was found to be a direct allowed transition, which is taken place between the bonding and antibonding molecular energy levels. The reported results herein are essential in revealing the viability of these natural dyes for potential applications in organic electronics, including organic photovoltaics, photodiodes, and sensors.

Effect of ZnO Nanomaterial and Red and Green Cabbage Dyes on the Performance of Dye-Sensitised Solar Cells

Visible light can be converted into electricity using dye sensitised solar cells (DSSCs), with their performance mainly based on the type of dye used as a sensitiser. Currently, dyes extracted from natural sources are highly preferred by researchers in this field. Natural dyes reduce the high cost of metal complex sensitisers and replace expensive processes of chemical synthesis with simple extraction processes. Natural dyes are environmentally friendly, abundant, easily extractable, and safe. Their application has become a promising development in DSSC technology. In this study, two natural dyes extracted from the plant leaves of green cabbage (GC) and red cabbage (RC) that were used as sensitisers. The performance characteristics of RC and GC extracts were investigated using both cyclic voltammetry and amperometry methods for solar cell detection. At an extraction temperature of 60 °C maintained for 8 h under optimum conditions, the measured values of maximum power (Pm), fill factor (FF), and efficiency (η) were 1.36 mW/cm2, 92.34%, and 0.161% for RC, and 0.349 mW/cm2, 44.19%, and 0.095% for GC, respectively. The RC and GC extracts exhibited excellent electrochemical performance with respect to current density potential and good cycling stability.

Nanoliposomal encapsulation mediated enhancement of betalain stability: Characterisation, storage stability and antioxidant activity of Basella rubra L. fruits for its applications in vegan gummy candies

Betalains are violet-red, natural food grade pigments with health benefits; however, their stability limits its use in industrial food processing. This can be overcome by placing the betalains in lecithin nanoliposomes (NLs), which causes a 76% improvement of betalain colour and stability. Extended sonication time (8 min) lowered the zeta potential (-47.5 to -40.8), and particle size (74.23 to 55.35 nm). Zeta potential, particle size, and polydispersity index of Betalain NLs (BNLs) didn't change significantly during storage (40 days). Degradation in the colour of BNLs was observed only at 121 °C (20 min) while the native juice degraded at 100 °C (20 min). BNLs were incorporated in gummy candies (GuCa) to improve its colour stability. The betalain retention, colour, texture, antioxidant activity, and shelf-life of the GuCa during storage (5 °C, 28 days) demonstrated the efficacy of BNLs to be explored as a natural colourant for the food industry.

An innovative cell imaging by beet root extracted pigment

Fluorescent dyes are of immense interest due to their nontrivial applications in cell imaging to observe different micro organelles and their functions. We have discovered organic Beet-root extracted water soluble fluorescent (BREWSF) dye as an efficient pigment for effective cell imaging. The extraction of this pigment from beet root and its preservation is very easy and cost effective. The BREWSF dye is characterized by IR, UV-Vis, NMR, mass, fluorescence spectroscopy and flowcytometry. By applying this dye on different types of human cells we obtained very good results in fluorescence microscopy, flowcytometry and confocal cell imaging. We also have noticed that this dye takes very less internalization time to produce very good fluorescence image and flowcytometry results of cells and also remains stable at different pH levels.

Performance Enhancement of Betanin Solar Cells Co-Sensitized with Indigo and Lawsone: A Comparative Study

Co-sensitization is an important strategy toward efficiency enhancement of solar cells by enabling better light harvesting across the solar spectrum. Betanin is a natural dye which absorbs light in the major portion of the incident solar spectrum (green region) and is the most efficient natural pigment used in dye-sensitized solar cells. This study investigates the performance enhancement of a betanin solar cell by co-sensitizing it with two natural pigments which show complementary light absorption, i.e., indigo and lawsone, absorbing in the red and blue regions of the solar spectrum, respectively. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the pigment molecules, derived from density functional theory (DFT) simulations, confirmed their optimal alignment with respect to the conduction band energy of the TiO₂ semiconductor and reduction potential energy level of the I^-/I₃ ^- electrolyte, a necessary requirement for optimal device performance. Lawsone solar cells displayed better performance, showing average efficiencies of 0.311 ± 0.034%, compared to indigo solar cells showing efficiencies of 0.060 ± 0.004%. Betanin was co-sensitized with indigo and lawsone, and the performances of the co-sensitized solar cells were compared. The betanin/lawsone co-sensitized solar cell showed a higher average efficiency of 0.793 ± 0.021% compared to 0.655 ± 0.019% obtained for the betanin/indigo co-sensitized solar cell. An 11.7% enhancement in efficiency (with respect to betanin) was observed for the betanin/indigo solar cell, whereas a higher enhancement of 25.5% was observed for the betanin/lawsone solar cell. Electrochemical impedance spectroscopy studies confirmed that the higher efficiency can be attributed to the higher electron lifetime of 313.8 ms in the betanin/lawsone co-sensitized solar cell compared to 291.4 ms in the betanin/indigo solar cell. This is due to the energy levels being more optimally aligned in lawsone compared to that of indigo, as observed in the DFT studies, and the lack of dipole moment in indigo, resulting in more efficient charge separation and charge transfer in lawsone.

Optimizing a Simple Natural Dye Production Method for Dye-Sensitized Solar Cells: Examples for Betalain (Bougainvillea and Beetroot Extracts) and Anthocyanin Dyes

We present a study about the sensitizers extracted from natural resources. This paper focuses on how to select, extract and characterize natural dyes, giving some guides to establish a protocol for the whole process of fabricating and using these dyes. The influence of the extraction solvent and method, and of parameters such as pH are analyzed. Also, dye precursor and dye extract stability have been studied, as well as how the dye adsorbs onto substrates and the effect of mixing or concentrating the extracts. Results concerning betalain pigments present in bougainvillea and beetroot extracts, and anthocyanins in eggplant extracts, analyzed by using UV-Vis spectrometry, are included. As an example of application, we report procedures intended to test and enhance the dye potential as a main component of dye-sensitized solar cells (DSSCs). DSSCs mimic nature’s photosynthesis and have some advantages like an easy and low-cost fabrication procedure. Their efficiency depends on its design and fabrication process and also on the different components involved. Hence, optimizing each component is essential to achieve the best performance, and thus the dye used as a sensitizer is crucial. We fabricate cells by using a simple procedure: As the interest is focused on the sensitizer, the same consecutive steps are followed, varying only the dye extract. Among all the natural-dyes tested, beetroot extract reaches up to 0.47% cell efficiency, which is near the highest values found in literature for this pigment.

Analysis of the degradation of betanin obtained from beetroot using Fourier transform infrared spectroscopy

Betalains are vacuolar pigments present in tubers, flowers or fruits. Their use in the food industry is significant because they are considered bioactive completely safe to consume. However, betalains are susceptible to temperature which affects their stability. The most of the available methods that determine stability involve high costs, are destructive and generate waste. In this work was evaluated the thermal degradation of betalain at 75 °C for several intervals of time, by using different techniques. Colorimetry showed a change in the tone angle (h°) from 359.76° to 20.54° after the heat-treatment, suggesting thermal degradation by changing the color from violet to red-orange. High-pressure liquid chromatography, shows the decrease of the concentration of betanin in addition to the formation of neobetanin, the main degradation product in betalains. UV-visible spectrophotometry suggest also thermal degradation of betanin, by the decrease of the absorption at 538 nm caused by the heat treatment. Finally, Fourier transform infrared spectroscopy (FTIR) showed a decrease in the intensity of two absorption bands at 1243 and 879 cm^-1, corresponding to the C-O and C-C vibrations of the carboxylic acid respectively after heat treatment. These results suggest that the main route of degradation corresponds to decarboxylation. We propose the use of FTIR spectroscopy as a practical alternative for the analysis of the degradation of natural dyes during storage, making evident the possible use of this methodology for industrial applications.

Extraction of red beet extract with β-cyclodextrin-enhanced ultrasound assisted extraction: A strategy for enhancing the extraction efficacy of bioactive compounds and their stability in food models

Improving the extraction efficiency and stability of red beet compounds has gained the attention of researchers due to their high nutritional and health benefits. In this study, β-cyclodextrin (β-CD) enhanced ultrasound assisted extraction was used for the extraction of red beet extract, and lyophilized extracts were characterized with FTIR and DSC analyses. The samples extracted with aqueous 5% β-CD solutions revealed the highest content of betanin (2.243 ± 0.04 mg) and total phenolic compounds (20.03 ± 1.28 mg GAE/g DW), and the highest DPPH inhibition activity (59.87 ± 4.94%). Additionally, complexation with β-CD significantly enhanced the stability of betanin, phenolic compounds and antiradical activity in the stored beverage and gummy candy models at various pH and temperature conditions during 28 days. In conclusion, β-CD-enhanced ultrasound assisted extraction is a suitable approach to extracting and stabilizing the red beet compounds for application in food, nutraceutical, and medical fields.

Structure and Photoelectrical Properties of Natural Photoactive Dyes for Solar Cells

A series of natural photoactive dyes, named as D1–D6 were successfully extracted from six kinds of plant leaves for solar cells. The photoelectrical properties of dyes were measured via UV-Vis absorption spectra, cyclic voltammetry as well as photovoltaic measurement. To theoretically reveal the experimental phenomena, the chlorophyll was selected as the reference dye, where the ground and excited state properties of chlorophyll were calculated via density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The experimental results show that the absorption peaks of those dyes are mainly distributed in the visible light regions of 400–420 nm and 650–700 nm, which are consistent with the absorption spectrum of chlorophyll. The photoelectrical conversion efficiencies of the solar cells sensitized by the six kinds of natural dyes are in the order of D1 > D4 > D2 > D5 > D6 > D3. The dye D1 performance exhibits the highest photoelectrical conversion efficiency of 1.08% among the investigated six natural dyes, with an open circuit voltage of 0.58 V, a short-circuit current density of 2.64 mA cm−2 and a fill factor of 0.70.

Performance and stability analysis of curcumin dye as a photo sensitizer used in nanostructured ZnO based DSSC

Environmental friendly natural dye curcumin extracted from low-cost Curcumina longa stem is used as a photo-sensitizer for the fabrication of ZnO-based dye-sensitized solar cells (DSSC). Nanostructured ZnO is fabricated on a transparent conducting glass (TCO), using a cost-effective chemical bath deposition technique. Scanning electron microscopic images show hexagonal patterned ZnO nano-towers decorated with several nanosteps. The average length of ZnO nano-tower is 5μm and diameter is 1.2μm. The UV-Vis spectroscopic study of the curcumin dye is used to understand the light absorption behavior as well as band gap energy of the extracted natural dye. The dye shows wider absorption band-groups over 350-470nm and 500-600nm with two peaks positioned at 425nm and 525nm. The optical band gap energy and energy band position of the dye is derived which supports its stability and high electron affinity that makes it suitable for light harvesting and effortless electron transfer from dye to the semiconductor or interface between them. FTIR spectrum of curcumin dye-sensitized ZnO-based DSSC shows the presence of anchoring groups and colouring constitutes. The I-V and P-V curves of the fabricated DSSC are measured under simulated light (100mW/cm²). The highest visible light to electric conversion efficiency of 0.266% (using ITO) and 0.33% (using FTO) is achieved from the curcumin dye-sensitized cell.

An Experimental and Theoretical Investigation of the Electronic Structures and Photoelectrical Properties of Ethyl Red and Carminic Acid for DSSC Application

The photoelectrical properties of two dyes-ethyl red and carminic acid-as sensitizers of dye-sensitized solar cells were investigated in experiments herein described. In order to reveal the reason for the difference between the photoelectrical properties of the two dyes, the ground state and excited state properties of the dyes before and after adsorbed on TiO₂ were calculated via density functional theory (DFT) and time-dependent DFT (TDDFT). The key parameters including the light harvesting efficiency (LHE), the driving force of electron injection ( Δ G inject ) and dye regeneration ( Δ G regen ), the total dipole moment ( μ normal ), the conduction band of edge of the semiconductor ( Δ E CB ), and the excited state lifetime (τ) were investigated, which are closely related to the short-circuit current density ( J sc ) and open circuit voltage ( V oc ). It was found that the experimental carminic acid has a larger J sc and V oc , which are interpreted by a larger amount of dye adsorbed on a TiO₂ photoanode and a larger Δ G regen , excited state lifetime (τ), μ normal , and Δ E CB . At the same time, chemical reactivity parameters illustrate that the lower chemical hardness (h) and higher electron accepting power (ω⁺) of carminic acid have an influence on the short-circuit current density. Therefore, carminic acid shows excellent photoelectric conversion efficiency in comparison with ethyl red.

Proteomic Analysis of Hylocereus polyrhizus Reveals Metabolic Pathway Changes

Red dragon fruit or red pitaya (Hylocereus polyrhizus) is the only edible fruit that contains betalains. The color of betalains ranges from red and violet to yellow in plants. Betalains may also serve as an important component of health-promoting and disease-preventing functional food. Currently, the biosynthetic and regulatory pathways for betalain production remain to be fully deciphered. In this study, isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analyses were used to reveal the molecular mechanism of betalain biosynthesis in H. polyrhizus fruits at white and red pulp stages, respectively. A total of 1946 proteins were identified as the differentially expressed between the two samples, and 936 of them were significantly highly expressed at the red pulp stage of H. polyrhizus. RNA-seq and iTRAQ analyses showed that some transcripts and proteins were positively correlated; they belonged to “phenylpropanoid biosynthesis”, “tyrosine metabolism”, “flavonoid biosynthesis”, “ascorbate and aldarate metabolism”, “betalains biosynthesis” and “anthocyanin biosynthesis”. In betalains biosynthesis pathway, several proteins/enzymes such as polyphenol oxidase, CYP76AD3 and 4,5-dihydroxy-phenylalanine (DOPA) dioxygenase extradiol-like protein were identified. The present study provides a new insight into the molecular mechanism of the betalain biosynthesis at the posttranscriptional level.