Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications

Botany, phytochemistry, pharmacology, and applications of Pandanus amaryllifolius Roxb.: A review

Pandan (Pandanus amaryllifolius Roxb.), a member of the Pandanaceae family, has been consumed as food and medicine since ancient times. The current paper provides an overview of the botanical profile, phytochemistry, pharmacology, and applications of P. amaryllifolius. Information regarding P. amaryllifolius was collected from online sources (using PubMed, Science Direct, Google Scholar, Web of Science, ACS, and CNKI) as well as traditional textbooks. Over 100 compounds have been identified, including its characteristic components 2-Acetyl-1-pyrroline and Pandanus alkaloids. Several therapeutic uses of P. amaryllifolius, such as antioxidant, hypoglycemic, antimicrobial, and antitumor activities, have been demonstrated in modern pharmacological studies. Additionally, it could be applied in various fields, including food, energy, material, and the environment. Continued research on P. amaryllifolius can contribute to the development of new drugs and therapies for various diseases. And further studies are needed to improve its utilization.

Pitaya Nutrition, Biology, and Biotechnology: A Review

Pitaya (Hylocereus spp.) is a member of the cactus family that is native to Central and South America but is now cultivated throughout the sub-tropical and tropical regions of the world. It is of great importance due to its nutritional, ornamental, coloring, medicinal, industrial, and high consumption values. In order to effectively utilize and develop the available genetic resources, it is necessary to appreciate and understand studies pertaining to the usage, origin, nutrition, diversity, evaluation, characterization, conservation, taxonomy, and systematics of the genus Hylocereus. Additionally, to gain a basic understanding of the biology of the plant, this review has also discussed how biotechnological tools, such as cell and tissue culture, micropropagation (i.e., somatic embryogenesis, organogenesis, somaclonal variation, mutagenesis, androgenesis, gynogenesis, and altered ploidy), virus-induced gene silencing, and molecular marker technology, have been used to enhance pitaya germplasm.

Research on dye sensitized solar cells: recent advancement toward the various constituents of dye sensitized solar cells for efficiency enhancement and future prospects

It is universally accepted that the financial advancement of a state is essentially dependent upon the energy sector as it is essential in the growth, development, and improvement of the farming, mechanical, and defense sectors. A dependable source of energy is expected to enhance society's expectation of everyday comforts. Modern industrial advancement, which is indispensable for any nation, relies upon electricity. The principal explanation behind the energy emergency is rapidly increasing the use of hydrocarbon resources. Thus, the use of renewable resources is essential to overcome this dilemma. The consumption of hydrocarbon fuels and their discharge has destructive consequences on our surroundings. Third-generation photovoltaic (solar) cells are latest encouraging option in solar cells. Currently, dye-sensitized solar cells (DSSC) utilize organic (natural and synthetic) dye and inorganic (ruthenium) as a sensitizer. The nature of this dye combined with different variables has brought about a change in its use. Natural dyes are a feasible alternative in comparison to expensive and rare ruthenium dye owing to their low cast, easy utility, abundant supply of resources, and no environmental threat. In this review, the dyes generally utilized in DSSC are discussed. The DSSC criteria and components are explained, and the progress in inorganic and natural dyes is monitored. Scientists involved in this emerging technology will benefit from this examination.

Alkanna tinctoria-based sustainable alkanin natural colorant for eco-dyeing of wool

The awareness of sustainability and widespread utilization of green technologies in textile dye houses are revolutionizing not only textile industries but related fields. The current study is concerned with ultrasonic (US)-assisted utilization of extracts of Alkanna tinctoria (a source of natural alkanin dye) for wool dyeing. The extracts are obtained in various media, and both extracts and wool fabrics have been  US treated for 15-60 min. Dyeing is performed by applying variable parameters and utilizing herbal-based extracts as a source of bio-mordant, hence improving the fastness rating and enhancing color strength. Good color strength and fastness ratings are obtained using irradiated extract at 4 pH when the US-treated wool fabric is dyed at 65 °C for 60 min before and after chemical and bio-mordanting. For comparative studies, chemical mordants are also employed. In contrast to chemical mordants, the bio-mordants have made the dyeing process more sustainable with good to excellent fastness rating.

Construction and characterization of organic photovoltaic cells sensitized by Chrysanthemum based natural dye

In this work, natural dyes from three different species of the same flower family (Chrysanthemum), which containing anthocyanin were extracted and properly prepared to be used as photosensitizers in DSSCs construction. The cells were fabricated with titanium dioxide nanoparticles (TiO₂) for the photoanodes, whereas platinum electrodes were used for the photocathodes. To understand the behavior of light absorption in addition to the coloring components present in the dyes and the molecular functional groups present in the samples, the UV-Vis absorption spectroscopy and FTIR spectroscopy were used respectively. The performance and efficiency of solar cells were evaluated to establish the photovoltaic criteria for each DSSC built. Through electrochemical characterizations, it was possible to notice that the highest photovoltaic conversion efficiency was obtained with the Chrysanthemum Violet (CV) cell, with efficiency (η) of 1.348%, compared to 1.229% and 0.485% for the Chrysanthemum Green (CG) and Chrysanthemum Blue (CB) cells, respectively. The CV cell also has the highest open circuit voltage (V_OC) at 0.58 V. The results corroborate to present the organic solar cells as a viable option for the electric energy generation.

Magnesium sulfate as a potential dye additive for chlorophyll-based organic sensitiser of the dye-sensitised solar cell (DSSC)

In this work, a new chlorophyll dye-sensitiser derived from mitragyna speciosa (MS) leaves, also known as Kratom, was employed for dye-sensitised solar cells (DSSCs). The influence of magnesium sulfate (MgSO₄), a low-cost dye additive, and suitable extraction solvents on the performance of DSSCs were examined. Here, the optical properties were investigated using UV-Visible spectroscopy and the functional anchoring group were investigated by FTIR spectroscopy. Meanwhile, the photovoltaic parameters were investigated by I-V measurements. The highest conversion efficiency is obtained when using a dye extracted from methanol solvent in combination with MgSO₄ additive, namely methanolic magnesium sulfate (MMSO). This higher power conversion efficiency is mainly attributed to the enhancement of the hydroxyl group in the MMSO dye solutions, which promotes higher dye adsorption and provides an organic dye passivation layer that reduces back-recombination in the cell. Furthermore, MgSO₄ aids in the replenishment of magnesium lost in the chlorophyll porphyrin ring during the degradation process. These combined effects have contributed to the overall conversion efficiency of the MMSO cell at 0.26 %, followed by 0.24 % for ethanolic magnesium sulfate (EMSO), respectively.

Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (Hylocereus) Species

Pitaya is one of the most preferred and produced tropical fruit species recently introduced to the Mediterrranean region in Turkey. Due to its nutritional fruits with high economic value, the popularity of pitaya increases steadily in Turkey as an alternative crop. No detailed nutritional analysis has been undertaken in Turkey so far on fruits of the pitaya species. In this study, we determined and compared some nutritional parameters in fruit flesh of two pitaya (dragon fruit) species (Hylocereus polyrhizus: Siyam and Hylocereus undatus: Vietnam Jaina) grown in the Adana province located in the eastern Mediterranean region in Turkey. The individual sugars, antioxidant activity, total phenolic content, phenolic compounds and volatiles were determined for the first time in Turkey on two pitaya species. The results showed that total phenol content and antioxidant capacity are notably higher in red-fleshed fruits than white-fleshed ones and the predominant phenolic compound in fruits of both species was quercetin. The total sugar content and most of the phenolic compounds in fruits of two pitaya species were similar. A total of 51 volatile compounds were detected by using two Solid Phase Micro Extraction (SPME) fibers, coupled with Gas Chromatography Mass Spectrometry (GC-MS) techniques, and more volatile compounds were presented in the white-fleshed species. Total phenolic content (TPC) of the red-fleshed and white-fleshed pitaya species were 16.66 and 17.11 mg GAE/100 g FW (fresh weight). This study provides a first look at the biochemical comparison of red-fleshed and white-fleshed pitaya species introduced and cultivated in Turkey. The results also showed, for the first time, the biochemical content and the potential health benefit of Hylocereus grown in different agroecological conditions, providing important information for pitaya researchers and application perspective.

Non-destructive measurement technique for water content in organic solvents based on a thermal approach

The water content of organic solvents is one of the crucial properties that affect the quality of the products and the efficiency of the manufacturing processes. The established water determination methods such as Karl Fischer titration and gas chromatography require skilled operators, specific reagents, and prolonged measurement time. Thus, they are not suitable for both on-line and in-line applications. In this study, we aim to develop a real-time and low-cost device with reliable accuracy. The proposed device based on a newly developed thermal approach could non-destructively detect the water content in multiple organic solvents at low concentrations with high accuracy and without the use of any specific reagent. Experiments were performed for the determination of water content in organic solvents such as methanol, ethanol, and isopropanol. The results show that the proposed device is feasible for the water content determination in methanol, ethanol, and isopropanol at 0–1% w/w. A Bland–Altman plot to illustrate the differences in measurements between the proposed device and coulometric Karl Fischer titration shows that most of the measurements lie within the limits of agreement where 95% of the differences between the two methods are expected to fall in the range of −0.13% and 0.09%.

The proposed device could non-destructively detect the water content in organic solvents at low concentrations with high accuracy and without any specific reagent. It could determine the water content in methanol, ethanol, and isopropanol at 0–1% w/w.

Toward Eco-Friendly Dye-Sensitized Solar Cells (DSSCs): Natural Dyes and Aqueous Electrolytes

Due to their low cost, facile fabrication, and high-power conversion efficiency (PCE), dye-sensitized solar cells (DSSCs) have attracted much attention. Ruthenium (Ru) complex dyes and organic solvent-based electrolytes are typically used in high-efficiency DSSCs. However, Ru dyes are expensive and require a complex synthesis process. Organic solvents are toxic, environmentally hazardous, and explosive, and can cause leakage problems due to their low surface tension. This review summarizes and discusses previous works to replace them with natural dyes and water-based electrolytes to fabricate low-cost, safe, biocompatible, and environmentally friendly DSSCs. Although the performance of “eco-friendly DSSCs” remains less than 1%, continuous efforts to improve the PCE can accelerate the development of more practical devices, such as designing novel redox couples and photosensitizers, interfacial engineering of photoanodes and electrolytes, and biomimetic approaches inspired by natural systems.

Facile production of chlorophyllides using recombinant CrCLH1 and their cytotoxicity towards multidrug resistant breast cancer cell lines

The purity of chlorophylls plays one of the key role for the production of chlorophyllides. We have designed a facile method for chlorophyll purification by twice solvent extraction. Twice extraction causes the loss of chlorophylls, but the purity of total chlorophylls can be enhanced 182%. Then, the purified chlorophylls can be converted to relatively pure chlorophyllides facilely. The results show that higher purity of chlorophyllides could be obtained when purified chlorophylls (ethanol-hexane extract) was used as starting materials than that of crude chlorophylls (ethanol-only extract). In biocompatibility test, the results showed that the prepared chlorophyllides can be applied as biomaterials. When the prepared chlorophyllides were applied to anticancer tests, they were active both in MCF7 and MDA-MB-231 (multidrug resistant breast cancer cells) cell lines. In addition, the results suggested that the prepared chlorophyllides could be a potential candidate of combination therapy with doxorubicin to breast cancers.

Eco-Friendly Dye-Sensitized Solar Cells Based on Water-Electrolytes and Chlorophyll

Organic solvents used for electrolytes of dye-sensitized solar cells (DSSCs) are generally not only toxic and explosive but also prone to leakage due to volatility and low surface tension. The representative dyes of DSSCs are ruthenium-complex molecules, which are expensive and require a complicated synthesis process. In this paper, the eco-friendly DSSCs were presented based on water-based electrolytes and a commercially available organic dye. The effect of aging time after the device fabrication and the electrolyte composition on the photovoltaic performance of the eco-friendly DSSCs were investigated. Plasma treatment of TiO₂ was adopted to improve the dye adsorption as well as the wettability of the water-based electrolytes on TiO₂. It turned out that the plasma treatment was an effective way of improving the photovoltaic performance of the eco-friendly DSSCs by increasing the efficiency by 3.4 times. For more eco-friendly DSSCs, the organic-synthetic dye was replaced by chlorophyll extracted from spinach. With the plasma treatment, the efficiency of the eco-friendly DSSCs based on water-electrolytes and chlorophyll was comparable to those of the previously reported chlorophyll-based DSSCs with non-aqueous electrolytes.

Extraction of polygenetic natural dyes from Cordyline fruticosa & Mussaenda erythrophylla for textile substrates

In the present study, cotton, silk and polyester yarns were dyed with the aqueous extracts of natural dyes from the pink leaves of Cordyline fruticosa and red sepals of Mussaenda erythrophylla. The dyeing was performed with mordants (Alum, Acetic acid, Copper sulphate and Lemon juice) and without mordant. UV-visible spectral analysis of natural dyes was determined. The selected dyed samples were assessed in terms of dye absorption percentage (E%), colour values (CIELAB), colour strength (K/S) and fastness properties. Various shades of ash-green and pink colours were obtained from the aqueous extracts of C. fruticosa leaves and M. erythrophylla sepals. Fastness results showed good to very good grades. It was observed that multiple colours were produced with different mordants from a single source; therefore, the dyes extracted from the above plants are polygenetic in nature.

Water-in-Oil-in-Water Nanoemulsions Containing Temulawak (Curcuma xanthorriza Roxb) and Red Dragon Fruit (Hylocereus polyrhizus) Extracts

Hydrophobic curcumin in temulawak extract and hydrophilic betacyanin in red dragon fruit extract are high-value bioactive compounds with extensive applications in functional food. In this study, these extracts were encapsulated in water-in-oil-in-water (w/o/w) nanoemulsions as a delivery system using a two-step high-energy emulsification method. PGPR and Span 20 were used as lipophilic emulsifiers for the primary w/o emulsion. The most stable w/o/w formulation with the least oil phase separation of 5% v/v consisted of w/o emulsion (15% w/w) and Tween 80 (1.5% w/w) as hydrophilic emulsifier. The formulation was characterized by a 189-nm mean droplet diameter, 0.16 polydispersity index, and –32 mV zeta potential. The freeze–thaw stability may be attributed to the combination of low w/o emulsion content and high Tween 80 concentration in the outer water phase of the w/o/w nanoemulsions used in this study. The IC₅₀ values of the nanoemulsion and the red dragon fruit extract were similar. It means that the higher concentration of curcumin in the nanoemulsions and the lower IC₅₀ value of temulawak extract ensured sufficient antioxidant activities of the w/o/w nanoemulsions.

Photoelectric performance evaluation of DSSCs using the dye extracted from different color petals of Leucanthemum vulgare flowers as novel sensitizers

In this work, the natural flower extracted dyes containing luteolin were prepared using three different specimens from daisy flowers family (Leucanthemum vulgare), namely yellow daisy, purple daisy and wine daisy, according to the color of its petals. Moreover, DSSCs were fabricated using nanosized titanium dioxide (TiO₂) as an anode; for the photocathodes, two different specimens were used: i) graphite electrode and ii) platinum electrode. To recognize the light absorption behavior, the existence of anchoring groups and coloring components of the extracted dyes were determined using absorption spectroscopy. The surface roughness of the photoanodes and cathodes were examined using atomic force microscope (AFM). The photovoltaic performance and efficiency of assembled DSSCs were evaluated to realize the influence of TiO₂ photoanodes on interaction of the Leucanthemum vulgare extracted dye molecules with graphite or platinum photocathodes. DSSCs fabricated with platinum cathode show higher conversion efficiency (η) of 0.6%, 0.4% and 0.8% for the yellow daisy, wine daisy and purple daisy, respectively. DSSCs sensitized with daisy wine dye showed highest open-circuit voltage (V_oc) of 520 mV and efficiency of 0.79% and 0.88%, for the graphite and platinum cathodes, respectively. These results showed that the DSSCs, using daisy flowers extracts as efficient photosensitizers, are suitable for the fabrication of environmentally safe, inexpensive, clean and renewable energy.

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.

Synthesis and applications of nano-TiO2: a review

TiO₂-based nanomaterials have attracted prodigious attention as a photocatalysts in numerous fields of applications. In this thematic issue, the mechanism behind the photocatalytic activity of nano-TiO₂ as well as the critical properties have been reviewed in details. The synthesis routes and the variables that affect the size and crystallinity of nano-TiO₂ have also been discussed in detail. Moreover, a newly emerged class of color TiO₂, TiO₂ in aerogel form, nanotubes form, doped and undoped form, and other forms of TiO₂ have been discussed in details. Photocatalytic and photovoltaic applications and the type of nano-TiO₂ that is more suitable for these applications have been discussed in this review.

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.

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31+G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31+G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100mW·cm^-2 yields a short-circuit current density (J_sc) of 3.23mA/cm², a photovoltage (V_oc) of 0.48V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2μm, the fastest electron transit of 0.22ms, and the longest electron lifetime of 4.29ms.

Coloring attributes of betalains: a key emphasis on stability and future applications

Organoleptic characteristics largely determine food acceptance, selection, and subsequent consumption.

Current application of phytocompound-based nanocosmeceuticals for beauty and skin therapy

Phytocompounds have been used in cosmeceuticals for decades and have shown potential for beauty applications, including sunscreen, moisturizing and antiaging, and skin-based therapy. The major concerns in the usage of phyto-based cosmeceuticals are lower penetration and high compound instability of various cosmetic products for sustained and enhanced compound delivery to the beauty-based skin therapy. To overcome these disadvantages, nanosized delivery technologies are currently in use for sustained and enhanced delivery of phyto-derived bioactive compounds in cosmeceutical sectors and products. Nanosizing of phytocompounds enhances the aseptic feel in various cosmeceutical products with sustained delivery and enhanced skin protecting activities. Solid lipid nanoparticles, transfersomes, ethosomes, nanostructured lipid carriers, fullerenes, and carbon nanotubes are some of the emerging nanotechnologies currently in use for their enhanced delivery of phytocompounds in skin care. Aloe vera, curcumin, resveratrol, quercetin, vitamins C and E, genistein, and green tea catechins were successfully nanosized using various delivery technologies and incorporated in various gels, lotions, and creams for skin, lip, and hair care for their sustained effects. However, certain delivery agents such as carbon nanotubes need to be studied for their roles in toxicity. This review broadly focuses on the usage of phytocompounds in various cosmeceutical products, nanodelivery technologies used in the delivery of phytocompounds to various cosmeceuticals, and various nanosized phytocompounds used in the development of novel nanocosmeceuticals to enhance skin-based therapy.

A TiO2modified abiotic–biotic process for the degradation of the azo dye methyl orange

Methyl orange was degraded by a TiO₂modified abiotic–biotic process involving synergetic mechanisms of adsorption, biodegradation, dye sensitization and LMCT.