Microalgae-based carbon capture and utilization (CCU) offers a promising negative emission technology that absorbs CO2 and generates valuable biomass. However, heavy metal pollutants in industrial flue gases can compromise carbon sequestration efficiency and bioproduct quality. Spirulina was investigated as a model organism for CO2 sequestration, using a modified Zarrouk's medium to integrate salt stress and an osmoprotectant to boost biomass yield under 15 % CO2. This approach enhances both biomass yield （380.83 mg L-1 d-1）and resistance to lead toxicity. Analytical assessments revealed that glycine betaine (GB) supplementation drastically reduced lead accumulation, decreasing the extracellular and intracellular contents by 39.7 % and 60.7 %, respectively. A notable decrease in extracellular dissolved organic matter was also observed. Furthermore, transcriptomic analyses confirmed that GB treatment strengthened osmotic stress responses and suppressed metal ion transport. These findings enhanced the feasibility of microalgae-based CCU technologies, marking significant progress in sustainable algal biotechnology.

Arthrospira platensis exhibits high tolerance to arsenic; however, the mechanisms underlying its response to the arsenic stress have not been fully elucidated. This study investigated the growth and resistance mechanisms of A. platensis under As3+ stress by measuring physiological and biochemical indices, conducting transcriptome sequencing, and validating the results through qPCR. The findings show that arsenic stress affected the antioxidant system and photosynthetic pigment synthesis in A. platensis. The algae mitigated arsenic-induced oxidative stress by increasing cellular metabolic rates, enhancing cell wall stability, and reducing membrane lipid peroxidation. Transcriptome analysis revealed that pathways related to oxidative phosphorylation and chlorophyll degradation were upregulated under arsenic stress, while the expression of membrane transporters was significantly downregulated. Additionally, the algae alleviated arsenic stress by producing hydrogen and polyamine compounds. This study provides insights into the mechanisms of A. platensis response to arsenic stress and elucidates the molecular pathways involved in the stress response to As3+.

Phycocyanin (PC) is of great significance to biomedicine and water environmental safety. Hence, it is indispensable to develop facile and rapid method for PC determination. In this investigation, a system containing lateral flow chromatography (LFC) strip (which was deposited with molecularly imprinted polymer (MIP) capped CdTe quantum dots (QDs) based mesoporous structured coated silica nanoparticles, SiO2@QDs@ms-MIP NPs) and miniaturized fluorimeter was first fabricated. In detail, a two-step strategy was utilized for preparation of SiO2@QDs@ms-MIP NPs, which consisted of modification of CdTe QDs onto the silica NPs first, and synthesis of mesoporous imprinting shell by using PC as template molecule and cetyltrimethylammonium bromide (CTAB) as surfactant. After that, novel fluorescence NPs possessing specific recognition and sensitivity toward PC in seawater and lake water were acquired. The resulting fluorescent sensing system exhibited outstanding performances, which included excellent sensitivity (4.5 nmol/L), satisfactory specificity (imprinting factor, 2.31), appropriate linearity range (0.01-5 μmol/L), good recovery (96.0-101.7 %), excellent stability (relative standard deviation, RSD<1.1 %), wonderful reproducibility (RSD<1.1 %), and excellent anti-interference ability. The results of the fluorescent sensing system were superior to those of the commonly used ultraviolet (UV) method. The proposed strategy showed great potential for fast (<10 min) and convenient fluorescence detection of PC in real samples.

Despite significant advancements in the medical treatment of primary hepatocellular carcinoma (PHC) in recent years, enhancing therapeutic effects and improving prognosis remain substantial challenges worldwide.

To investigate the expression levels of serum vascular endothelial growth factor (VEGF) and interleukin (IL)-17 in patients with PHC and evaluate their diagnostic value while exploring their relationship with patients' clinical characteristics.

The study included 50 patients with confirmed PHC who visited Wuhan Hanyang Hospital from January 2021 to January 2022, and 50 healthy individuals from the same period served as the control group. Serum VEGF and IL-17 levels in both groups were measured by Enzyme-Linked Immunosorbent Assay, and their diagnostic value was assessed using receiver operating characteristic (ROC) curves. Pearson correlation analysis was performed to examine the relationship between serum VEGF and IL-17 levels. Pathological data of the PHC patients were analyzed to determine the relationship between serum VEGF and IL-17 levels and pathological characteristics.

Serum VEGF and IL-17 levels were significantly higher in the study group compared to the control group (P < 0.05). No significant association was observed between serum VEGF and IL-17 levels and gender, age, combined cirrhosis, tumor diameter, or degree of differentiation (P > 0.05). However, there was a significant relationship between clinical TNM stage, tumor metastasis, and serum VEGF and IL-17 levels (P < 0.05). Correlation analysis revealed a positive correlation between serum VEGF and IL-17 (P < 0.05). ROC analysis demonstrated that both serum VEGF and IL-17 had good diagnostic efficacy for PHC.

Serum VEGF and IL-17 levels were significantly higher in PHC patients compared to healthy individuals. Their levels were closely related to pathological features such as tumor metastasis and clinical TNM stage, and there was a significant positive correlation between VEGF and IL-17. These biomarkers may serve as valuable reference indicators for the early diagnosis and treatment guidance of PHC.

C-phycocyanin (C-PC) is the main component of water-soluble light-harvesting complexes (phycobilisomes, PBS) of cyanobacteria. PBS are involved in the absorption of quantum energy and the transfer of electronic excitation energy to the photosystems. A specific environment of C-PC chromophoric groups is provided by the protein matrix structure including protein-protein contacts between different subunits. Registration of C-PC spectral characteristics and the fluorescence anisotropy decay have revealed a significant pH influence on the chromophore microenvironment: at pH 5.0, a chromophore is more significantly interacts with the solvent, whereas at pH 9.0 the chromophore microenvironment becomes more viscous. Conformations of chromophores and the C-PC protein matrix have been studied by Raman and infrared spectroscopy. A decrease in the medium pH results in changes in the secondary structure either the C-PC apoproteins and chromophores, the last one adopts a more folded conformation.

Development of biomolecules coordinated iron ions-based Fenton agents is highly desirable for chemodynamic therapy in term of demanded biocompatibility and enhanced Fenton activity at tumor microenvironmental pH of 6.5. Herein, phycocyanin (PC), the only FDA-approved natural coloring agent, was selected to coordinate with iron ions. The spectroscopic investigations disclosed that PC displayed pH-dependent spectral and conformational responses upon addition of Fe ions. As a result, the effective formation of Fe-PC coordination merely occurred at pH 7 due to a less folded polypeptide matrix of PC. The formed Fe-PC coordination exerted an enhanced Fenton activity at pH 6.5 as attested by 3, 3', 5, 5'-tetramethlbenzidine assay and steady-state kinetic analysis. These findings not only provide fundamental insights of Fe-PC coordination but also highlight the potential biomedical significance of Fe-PC for severing as an effective Fenton agent in chemodynamic therapy.

Cyano-phycocyanin (C-PC) is a light-absorbing biliprotein found in cyanobacteria, commonly known as blue-green algae. Due to its antioxidative, anti-inflammatory, and anticancer properties, this protein is a promising substance in medicine and pharmaceuticals. However, cyanobacteria tend to bind heavy metals from the environment, making it necessary to ensure the safety of C-PC for the development of pharmaceutical products, with C-PC isolated from naturally collected cyanobacterial biomass. This study aimed to determine the content of the most toxic heavy metals, arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in C-PC isolated from different cyanobacterial biomasses collected in the Kaunas Lagoon during 2019-2022, and compare them with the content of heavy metals in C-PC isolated from cultivated Spirulina platensis (S. platensis). Cyanobacteria of Aphanizomenon flos-aquae (A. flos-aquae) dominated the biomass collected in 2019, while the genus Microcystis dominated the biomasses collected in the years 2020 and 2022. Heavy metals were determined using inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS analysis revealed higher levels of the most investigated heavy metals (Pb, Cd, and As) in C-PC isolated from the biomass with the dominant Microcystis spp. compared to C-PC isolated from the biomass with the predominant A. flos-aquae. Meanwhile, C-PC isolated from cultivated S. platensis exhibited lower concentrations of As and Pb than C-PC isolated from naturally collected cyanobacterial biomass.

Phycocyanin (PC), as a pigment-protein complex, aggregates and precipitates in acidic environments. In this context, complex formation with anionic polysaccharides is a strategy to enhance protein solubility. Besides, acidic conditions negatively affect the inherent blue color of PC, which can be prevented by encapsulation. Thereupon, in the present study, two different biopolymer-based systems, namely complexes and hydrogel beads, were prepared to increase PC solubility and its color stability under acidic conditions, respectively. Fucoidan and κ-carrageenan (KC) were separately utilized to make a complex with PC. Calcium alginate-pregelatinized corn starch (PCS) composite gel beads were used to encapsulate PC. The prepared samples were added into model systems simulating acidic conditions and then characterized during storage at 4 and 25 °C under dark conditions. Appropriate colloidal stabilities were observed for fucoidan/PC and KC/PC model systems. The color of the samples remained stable at 4 °C. As well, the bead carriers (i.e. alginate-PCS) properly protected PC against low pH conditions over time at 4 °C. Thereupon, the blue color of the beads satisfactorily remained stable at this temperature. The findings showed that complexation with fucoidan or KC and encapsulation in mixed hydrogel beads are promising routes for improving PC solubility and its color stability, respectively.

This study aimed to purify, characterise and stabilise the natural food colourant, R-phycocyanin (R-PC), from the red algae Porphyra spp. (Nori). We purified R-PC from dried Nori flakes with a high purity ratio (A₆₁₈/A₂₈₀ ≥ 3.4) in native form (α-helix content 53%). SAXS measurements revealed that R-PC is trimeric ((αβ)₃) in solution. The thermal denaturation of α-helix revealed one transition (T_m at 52 °C), while the pH stability study showed R-PC is stable in the pH range 4-8. The thermal treatment of R-PC at 60 °C has detrimental and irreversible effects on R-PC colour and antioxidant capacity (22 % of residual capacity). However, immobilisation of R-PC within calcium alginate beads completely preserves R-PC colour and mainly retains its antioxidant ability (78 % of residual capacity). Results give new insights into the stability of R-PC and preservation of its purple colour and bioactivity by encapsulation in calcium alginate beads.

There is an increasing demand for more healthy and sustainable diets, which led to an interest in replacing synthetic colors with natural plant-based ones. Phycocyanin, which is commonly extracted from Spirulina platensis, has been explored as a natural blue pigment for application in the food industry. It is also used as a nutraceutical in food, cosmetic, and pharmaceutical products because of its potentially beneficial biological properties, such as radical scavenging, immune modulating, and lipid peroxidase activities. The biggest challenges to the widespread application of phycocyanin for this purpose are its high sensitivity to chemical degradation when exposed to heat, light, acids, high pressure, heavy metal cations, and denaturants. Consequently, it is of considerable importance to improve its chemical stability, which requires a thorough knowledge of the relationship between the structure, environment, and chemical reactivity of phycocyanin. To increase the application of this natural pigment and nutraceutical within foods and other products, the structure, biological activities, and factors affecting its stability are reviewed, as well as strategies that have been developed to improve its stability. The information contained in this article is intended to stimulate further studies on the development of effective strategies to improve phycocyanin stability and performance.

Heavy metal is a worldwide hazardous material, and many efforts were made to detect them sensitively and selectively. R-phycoerythrin (R-PE), a marine fluorescent protein, is abundant in red algae and participates in photosynthesis. In this work, the fluorescence spectroscopy and molecular mechanism of Hg2+ ions and R-PE were further explored through fluorescence spectrum measurements, time-resolved fluorescence lifetimes, peak fitting of Fourier transform infrared spectroscopy, and molecular docking simulation in this study. It was proved by fluorescent spectrum measurements that Hg2+ ions could lead to static fluorescence quenching. Besides, the interaction was a spontaneous and exothermic process driven by hydrogen bond and Van der Waals (VDW) force. Importantly, Hg2+ ions bound to 78LYS and 82CYS on the α chain and 73CYS and 82CYS on the β chain, which resulted in the structural changes of the peptide chain and affected the secondary structure contents of R-PE. This study further explained the effect of Hg2+ ions on marine fluorescent protein R-PE.

As a global environmental pollution problem, heavy metal pollution has brought great harm to human beings. In this work, we studied the toxicity of Hg²⁺ on allophycocyanin (APC) at the molecular level. Firstly, APC was extracted and purified from Spirulina platensis mud and its purity (A₆₅₀/A₂₈₀) reached 3.75. In addition, the fluorescence intensity of APC decreased with increasing Hg²⁺ concentration from 0 to 5 × 10^-6 mol L^-1. The theoretical calculation and experimental results showed that the fluorescence quenching of APC by Hg²⁺ was static and had a good linear relationship. Moreover, the UV-Vis spectra of APC showed a significant decrease at 200 nm and 650 nm with the increase of Hg²⁺ concentration from 0 to 5×10^-6 mol L^-1, and a red-shift at 200 nm, which indicated that Hg²⁺ not only affected the structure of APC but also affected the light absorption and photosynthetic function of APC. Furthermore, the results of molecular simulation demonstrate that Hg²⁺ combinations with the Met77, Cys81 in the α chain and the Arg77, Cys81 in the β chain, which interact between the peptide chain and the chromophore, and Hg²⁺ forms a Hg-S bond with -SH. This study provides new insights into the structure and how Hg²⁺ effect the optical properties of APC.

Composite gel beads using calcium alginate and different concentrations of pregelatinized corn starch (PCS) were produced to encapsulate phycocyanin (PC). Rheological properties of different sodium alginate/PCS/PC mixtures, structural and morphological properties of beads, and kinetic stability of encapsulated PC (upon heating at various time-temperature combinations) were then assessed. Rheological properties of the mixtures exhibited shear thinning behaviors. Aquagram revealed that the PC-containing beads had more water structure with weak‑hydrogen bonds. Morphological images represented less subsidence in the structures of composite gel beads, unlike PCS-free beads. Kinetic study showed that degradation rate constant values of PC encapsulated in composite gel beads (1.08-3.45 × 10^-4, 3.38-4.43 × 10^-4, and 5.57-15.32 × 10^-4 s^-1) were lower than those in PCS-free alginate gel beads (4.45 × 10^-4, 9.20 × 10^-4, and 18.04 × 10^-4 s^-1) at 40, 50, and 60 °C, respectively. This study suggests that the composite gel beads can improve PC stability.

Blue-green algae, also known as cyanobacteria, contain some of the most efficient light-harvesting complexes known. These large, colourful complexes consist of phycobiliproteins which are extremely valuable in the cosmetics, food, nutraceutical and pharmaceutical industries. Additionally, the colourful and fluorescent properties of phycobiliproteins can be modulated by metal ions, making them highly attractive as heavy metal sensors and heavy metal scavengers. Although the overall quenching ability metal ions have on phycobiliproteins is known, the mechanism of heavy metal binding to phycobiliproteins is not fully understood, limiting their widespread quantitative applications. Here, we show using high-resolution native mass spectrometry that phycobiliprotein complexes bind metal ions in different manners. Through monitoring the binding equilibria and metal-binding stoichiometry, we show in particular copper and silver to have drastic, yet different effects on phycobiliprotein structure, both copper and silver modulate the overall complex properties. Together, the data reveals the mechanisms by which metal ions can modulate phycobiliprotein properties which can be used as a basis for the future design of metal-related phycobiliprotein applications.

Uranium(U), a highly toxic radionuclide, is becoming a great threat to soil health development, as returning nuclear waste containing U into the soil systems is increased. Numerous studies have focused on: i) tracing the source in U contaminated soils; ii) exploring U geochemistry; and iii) assessing U phyto-uptake and its toxicity to plants. Yet, there are few literature reviews that systematically summarized the U in soil-plant system in past decade. Thus, we present its source, geochemical behavior, uptake, toxicity, detoxification, and bioremediation strategies based on available data, especially published from 2018 to 2021. In this review, we examine processes that can lead to the soil U contamination, indicating that mining activities are currently the main sources. We discuss the relationship between U bioavailability in the soil-plant system and soil conditions including redox potential, soil pH, organic matter, and microorganisms. We then review the soil-plant transfer of U, finding that U mainly accumulates in roots with a quite limited translocation. However, plants such as willow, water lily, and sesban are reported to translocate high U levels from roots to aerial parts. Indeed, U does not possess any identified biological role, but provokes numerous deleterious effects such as reducing seed germination, inhibiting plant growth, depressing photosynthesis, interfering with nutrient uptake, as well as oxidative damage and genotoxicity. Yet, plants tolerate U toxicity via various defense strategies including antioxidant enzymes, compartmentalization, and phytochelatin. Moreover, we review two biological remediation strategies for U-contaminated soil: (i) phytoremediation and (ii) microbial remediation. They are quite low-cost and eco-friendly compared with traditional physical or chemical remediation technologies. Finally, we conclude some promising research challenges regarding U biogeochemical behavior in soil-plant systems. This review, thus, further indicates that the combined application of U low accumulators and microbial inoculants may be an effective strategy for the bioremediation of U-contaminated soils.

Phycoremediation is being considered as an eco-friendly and safe technology for toxics eradication from contaminated aquatic systems. The zinc biosorption capacity of Dunaliella sp. AL-1 was demonstrated. Zinc impacted cell growth and photosynthetic pigments accumulation showing exposure time and concentration-dependent effects. The investigation of the antioxidant protective response to zinc exposition proved a stimulation of guaiacol peroxidase (GPX) activity and an increased rate of total phenolics, flavonoids, condensed tannins and glutathione (GSH). The Box-Behnken design was used to optimize zinc removal conditions by Dunaliella sp. AL-1 strain. The maximum experimental zinc uptake was obtained when zinc concentration, algae dose, initial pH, and contact time were set at 25 mg/L, 0.5 g/L, 7.59 and 13 h 43 min, respectively. Under completely optimized conditions, the fraction of zinc removed intracellularly was much lower than the adsorbed on the cell surface. FTIR analysis Dunaliella sp. AL-1 biomass demonstrated that several functional groups as OH, CH₂, CO, PO, COO and CO may participate in the biosorption process. A comparative proteomic analysis through nano-HPLC coupled to LC-MS/MS, was performed from pre- and post-zinc treatments cells. Among 199 identified proteins, 60 were differentially expressed of which 41 proteins were down-regulated against 19 up-regulated ones. Target proteins have been demonstrated to be implicated in different metabolic processes mainly photosynthesis and antioxidant defenses.

This work has assessed the impact of copper oxide nanoparticles (CuONPs), designed via green route, toward photosynthetic apparatus on aquatic photoautotrophic organisms. In order to filling knowledge gaps, in vitro and in vivo assays were performed, using cyanobacterial phycocyanin (C-PC) from Arthrospira platensis and Lemna valdiviana plants (duckweed), respectively. Impairment in light energy transfer became evident in C-PC exposed to CuONPs, giving rise to an increase of light absorption and a suppression of fluorescence emission. Fourier transform infrared spectroscopy (FTIR) results showed that C-PC structures might be altered by the nanoparticles, also revealed that CuONPs preferably interacts with -NH functional groups. The data also revealed that CuONPs affected the chlorophyll a content in duckweed leaves. In addition, photosystem II (PSII) performance was significantly affected by CuONPs, negatively impacting the PSII photochemical network. In summary, the results point out that, even eco-friendly designed, CuONPs may negatively affect the photosynthetic process when accumulated by aquatic photoautotrophs.

The binding of C-phycocyanin (CPC), a light harvesting pigment with phycocyanobilin (PCB), a chromophore is instrumental for the coloration and bioactivity. In this study, structure-mediated color changes of CPC from Spirulina platensis during various enzymatic hydrolysis was investigated based on UV-visible, circular dichroism, infra-red, fluorescence, mass spectrometry, and molecular docking. CPC was hydrolyzed using 7.09 U/mg protein of each enzyme at their optimal hydrolytic conditions for 3 h as follows: papain (pH 6.6, 60 °C), dispase (pH 6.6, 50 °C), and trypsin (pH 7.8, 37 °C). The degree of hydrolysis was in the order of papain (28.4%) > dispase (20.8%) > trypsin (7.3%). The sequence of color degradation rate and total color difference (ΔE) are dispase (82.9% and 40.37), papain (72.4% and 24.70), and trypsin (58.7% and 25.43). The hydrolyzed peptides were of diverse sequence length ranging from 8 to 9 residues (papain), 7-12 residues (dispase), and 9-63 residues (trypsin). Molecular docking studies showed that key amino acid residues in the peptides interacting with chromophore. Amino acid residues such as Arg86, Asp87, Tyr97, Asp152, Phe164, Ala167, and Val171 are crucial in hydrogen bonding interaction. These results indicate that the color properties of CPC might associate with chromopeptide sequences and their non-covalent interactions.