As a remarkable model protein for studying excitation energy transfer (EET), Cryptophyte phycocyanin 645 (Cr-PC645) is not only important in the frontier research field on photosynthesis but also, like other kinds of phycocyanin, valuable in food and cosmetic industries as a kind of natural blue pigment protein. Here, we report a convenient preparation method for the purification of Cr-PC645 from cryptophytic algae, Chroomonas placoidea, mainly using hydrophobic interaction chromatography, and a study of EET characterization based on it. The final recovery of Cr-PC645 is 58.49

Photosynthesis is among the most essential biochemical processes on Earth. In nature, cryptophyte algae harness solar energy through specialized light-harvesting complexes. The excitation energy transfer (EET) among these pigments is highly sensitive to the local microenvironment, particularly pH variations resulting from proton gradients induced by fluctuating light intensities. However, the precise mechanisms by which such microenvironmental changes modulate EET in cryptophyte systems remain to be fully elucidated. In this work, we investigate the pH-dependent photophysical behavior and energy transfer dynamics of the light-harvesting complex phycocyanin 645 (PC645). Using pH as a controllable microenvironmental parameter, we performed femtosecond transient absorption (TA) spectroscopy under neutral and acidic conditions to probe ultrafast EET pathways through the selective excitation of specific chromophores. These experimental results are further complemented by hybrid quantum mechanics/molecular mechanics (QM/MM) calculations, which characterize the pigment-protein interactions and the local electrostatic environments. Drawing on these insights, we employed coherent modified Redfield theory (CMRT) to simulate the EET dynamics at pH 7 and pH 4. The present study provides experimental and theoretical insights into the adaptive response of PC645 to environmental perturbations and contributes to the understanding of energy-regulatory mechanisms in cryptophyte light-harvesting systems.

Mercury ion, as a highly hazardous heavy metal ion, can be easily ingested by humans via the aquatic products and water intake, and more worrying than that is the risk that the accumulation of Hg2+ in the body tissues is eliminated slowly, posing a grave threat to human health. Herein, a novel nano-silver hybrid material (CSWCNTs-PE-Ag) with oxidase-like activity was successfully fabricated to conduct a rapid detection of Hg2+ in aquatic products, which consists of the carboxylated single-walled carbon nanotubes grafted on the analytical grade Cryptophyte phycoerythrin 566 (Cr-PE566) and in-situ synthesis of nano-silver with the face-centered cubic crystal structure. By introducing Hg2+, the enhancement of catalytic activities of the hybrid material causes an oxidation of 3,3 ',5,5 '-tetramethylbenzidine (TMB) by yielding more superoxide anions (O2 center dot-) and a subsequent concentration-dependent color change, which offers new avenues for developing a CSWCNTs-PE-Ag / TMB colorimetric sensing platform to achieve the quantitative detection of the concentration of Hg2+. Under the optimized conditions, for this sensing platform, the detection limit reach as low as 100 nM and the linear range was found to be between 5 and 100 mu M. Moreover, a negligible interference from potential interferents common in aquatic tissues exhibited the high specificity of the constructed sensing platform, proving to be suitable for the practical detection of oysters, clams, and river shrimps. Our study proposes a valuable alternative for the expeditious quantitative detection of mercury ions, which hold considerable application prospects in the contamination detection of real aquatic products.

Phycocyanin 620 (PC620) is a water-soluble blue phycobiliprotein (PBP) originating from hot spring cyanobacteria - Thermosynechococcus vulcanus (Tv). It has been recognized as a valuable material with great potential for application to theoretical studies and commercial products. So, in our work, the PC620 was purified by a minimalistic procedure through hydrophobic chromatography and used for the study of excitation energy transfer (EET) characterization. The results show that the obtained PC620 with a final recovery of 81.5 % and an analytical grade purity at 5.21 (A(620)/A(280)) was reached through the process that consisted of liquid nitrogen grinding, 20 %-50 % ammonium sulfate fractionation and one-step hydrophobic interaction chromatography. The final PC620 showed a maximum absorption peak at 620 nm, a fluorescence emission peak at 652 nm and a positive peak of circular dichroism (CD) spectra in the visible range at 626 nm. Then, joint analysis of absorption spectra, fluorescence spectra, and CD spectra confirmed that the structural and functional integrity of the samples was retained compared with natural PC620. In addition, the exciton coupling in PC620 has been excluded by CD measurements. Furthermore, in an accurate experimental determination of the EET lifetime in PC620, two energy migration pathways from alpha 84 to beta 84 in a period of similar to 0.25 ps and then from beta 155 to beta 84 in a period of similar to 5 ps were directly resolved by ultrafast time-resolved spectroscopy. The calculated results indicated that the EET process in PC620 is dominated by the F & ouml;rster resonance energy transfer (FRET) mechanism. This work should be conducive to the highly efficient preparation of the analytical grade PC620 using a substantially simpler purification method for exploring the applications of theoretical research and the commercial field.

We consider the following Schr & ouml;dinger-Newton system with negative criti-cal nonlocal term in R-3, in R-3, - Delta * u - phi * |u| <^> 3 * u = a(x) * f(u) ,\\ - Delta phi=|u|<^> 5 , where a and f satisfy some certain conditions. By using the variational method and analytical techniques, we obtain the existence of positive ground state solutions which improves the recent results in the literature.

Cryptomonad phycoerythrin 545 (PE545) is an important type of phycobiliprotein in basic research and technological innovations. Herein, we report a minimalistic hydrophobic chromatography method for its purification. High purity was achieved, with a purity ratio (A545/A280) of 13.66 and a recovery ratio of 78.63 %. Following SDS-PAGE, Coomassie Brilliant Blue staining revealed three bands at 9 kDa, 10 kDa, and 20 kDa, corresponding to alpha 1, alpha 2 and beta subunits. Multiple spectral characteristics were analyzed to ensure that optical activity was consistent with that of the natural protein. Absorption and fluorescence spectroscopies of purified PE545 displayed a strong absorption peak at 545 nm, a shoulder peak at 564 nm, and a fluorescence emission peak at 587 nm, which confirmed unchanged energy transfer properties. Furthermore, the structural and functional integrity, especially the existence of strongly coupled central chromophore pairs with excitation delocalization, was verified by circular dichroism and ultrafast absorption spectroscopy. From the studies of ultrafast absorption spectroscopy of excitation energy transfer (EET) of PE545, four decay components with lifetimes at 0.5 ps, 2.2 ps, 63 ps, and 3000 ps were obtained. In addition, the dynamics of these components confirmed the EET pathways from the central PEB chromophore pairs to the peripheral pigments and localized in the lowest state. Our work will be of considerable value for both fundamental research and applications of PE545.

Quantum beats lasting a few hundred femtoseconds have been regarded as signatures of quantum energy transfer in photosynthetic antennae. The fragile coherence at room temperature casts doubt on its long-lived feature arising from the electronic coherence. Recently, the long-lived exciton–vibrational coherences of several hundred femtoseconds via quantum phase synchronization of the resonant higher frequency collective vibrational modes have been observed in core antenna allophycocyanin from algae. The long-lived coherence has an inherent property of protecting the coherence against the noisy environment. This is achieved by dissipation of the resonant anti-symmetric collective vibrational modes coupled to the excitonic levels, which have fast dephasing, leaving only the non-dissipative correlated symmetric modes [R. Zhu et al., Nat. Commun. 15, 3171 (2024)], which is different from that induced by the environmental low frequency modes. Coherence with a lifetime constant of 200 fs at room temperature has been observed in the cryptophyte phycoerythrin 545 (PE545) antenna before, while its origin, i.e., pure electronic or exciton–vibrational, remains to be explored. Here, we investigated coherent energy transfer dynamics in PE545 via two-dimensional electronic spectroscopy. A long-lasting coherence with a lifetime constant of 270 fs in the dynamical Stokes shift dynamics was observed. Especially, the high frequency vibrational mode at 1150 cm−1 is absent in the electronic energy dissipation process reflected in the dynamical Stokes’ shifts spectrum, which is near resonant with the electronic gap of 1080 cm−1. Therefore, the facts strongly suggest that the long-lived coherence in PE545 is realized by the resonant exciton–vibrational coupling via quantum phase synchronization.

IntroductionCryptophytes obtain energy through photosynthetic pigments and transfer it to the photosynthetic center on an ultrafast timescale. The mechanisms of such ultrafast excitation energy transfer (EET) in light-trapping complexes are a major focus of algal research. The closed-form phycoerythrin 566 (PE566) binds chemically distinct chromophores, exhibiting spectral properties that differ from those of other closed-form phycobiliproteins in cryptophytes. Elucidating the ultrafast energy transfer pathway of PE566 may provide a deeper understanding of the mechanisms involved in the initial stages of photosynthesis.MethodWe present a comprehensive description of the ultrafast energy transfer kinetics of PE566 under physiological conditions. A combined approach using ultrafast transient absorption (TA) spectroscopy and coherent modified Redfield theory (CMRT) was employed for theoretical modeling to investigate the ultrafast energy transfer between pigment molecules, including the exciton dynamics in PE566.Results and DiscussionThe results indicate that, in the PE566 dimer, the two phycoerythrobilins (PEBs) possess the highest excitation energies and act as the primary donors in the EET process. The two double-linked bilin584s serve as secondary energy transfer acceptors, exhibiting strong electronic coupling that leads to coherent delocalization of excited states. Two single-linked bilin584s and two bilin618s constitute the four lowest-energy exciton states. Ultimately, two efficient EET pathways were identified, with the lowest-energy bilin618s serving as the terminal acceptors for energy transfer in PE566. Our work clarifies the internal EET mechanism of Cryptophyta PE566, which may advance photophysical studies of phycobiliprotein systems.

Even with the current advancement, the treatment of industrial and aquaculture wastewater containing organic and inorganic pollutants is still one of the research focuses, and the development of photocatalysts degrading those contaminants under visible light has been considered an essential strategy. In this study, we reported a novel multifunctional photocatalytic material (nHAP-Ag3PO4) composed of natural nano-hydroxyapatite (nHAP) from salmon processing by-products, fish bones, with an in-situ Ag3PO4 loading, by a body-centered cubic structure. Under visible light irradiation, with organic dyes, tetracycline (TC) and Pb(II) as simulated water pollutants, it was found that nHAP-Ag3PO4 had an excellent degradation rate for organic dyes and TC, reaching more significant than 95

Phycocyanin 620 (PC620) is the outermost light-harvesting complex in phycobilisome of cyanobacteria, engaged in light collection and energy transfer to the core antenna, allophycocyanin. Recently, long-lived exciton–vibrational coherences have been observed in allophycocyanin, accounting for the coherent energy transfer [Zhu et al., Nat. Commun. 15, 3171 (2024)]. PC620 has a nearly identical spatial location of three α84–β84 phycocyanobilin pigment pairs to those in allophycocyanin, inferring an existence of possible coherent energy transfer pathways. However, whether PC620 undergoes coherent or incoherent energy transfer remains debated. Furthermore, accurate determination of energy transfer rates in PC620 is still necessary owing to the spectral overlap and broadening in conventional time-resolved spectroscopic measurements. In this work, the energy transfer process within PC620 was directly resolved by polarization-controlled two dimensional electronic spectroscopy (2DES) and global analysis. The results show that the energy transfer from α84 to the adjacent β84 has a lifetime constant of 400 fs, from β155 to β84 of 6–8 ps, and from β155 to α84 of 66 ps, fully conforming to the Förster resonance energy transfer mechanism. The circular dichroism spectrum also reveals that the α84–β84 pigment pair does not form excitonic dimer, and the observed oscillatory signals are confirmed to be vibrational coherence, excluding the exciton–vibrational coupling. Nodal line slope analysis of 2DES further reveals that all the vibrational modes participate in the energy dissipation of the excited states. Our results consolidate that the ultrafast energy transfer process in PC620 is incoherent, where the twisted conformation of α84 is suggested as the main cause for preventing the formation of α84–β84 excitonic dimer in contrast to allophycocyanin.

Abstract Cryptomonad phycoerythrin 545 is an important type of phycobiliprotein in basic research and technological innovations. Herein, we report a minimalistic hydrophobic chromatography method for its purification. High purity was achieved, with a purity ratio (A545/A280) of 13.66 and a recovery ratio of 78.63%. Following SDS-PAGE, Coomassie Brilliant Blue staining and Zn2+-enhanced UV fluorescence autoradiography revealed three bands at 9 kDa, 10 kDa, and 20 kDa, corresponding to α1, α2 and β subunits. Multiple spectral characteristics were analysed to ensure that optical activity was consistent with that of the natural protein. Absorption and fluorescence spectroscopies of purified phycoerythrin 545 displayed a strong absorption peak at 545 nm and a shoulder peak at 564 nm, and a fluorescence emission peak of at 587 nm, which confirmed unchanged energy transfer properties, and structural and functional integrity was verified by circular dichroism spectroscopy. Compared with published purification methods, this new purification protocol replaces two-step ammonium sulphate fractionation, dialysis, and size exclusion chromatography with a single chromatography step, thereby reducing the cost of large-scale kilogram-level commercial production.

Dye-sensitized solar cells (DSSCs) based on phycoerythrin have a simple preparation process and widely available raw materials, and are pollution-free, in addition to having good prospects for underwater applications. In this study, DSSCs based on cryptomonad phycoerythrin 545 (PE545) were fabricated independently or through synergistic sensitization with chlorophyll a (Chla) and chlorin e6. Their photoelectric properties were characterized using the solar cell I–V test system. After sensitization with PE545, PE545 plus chlorophyll a, and PE545 plus chlorin e6, the maximum photoelectric conversion efficiency values were 0.263

The in vivo degradation behavior of metallic nanoparticles (NPs) is very important for their biomedical applications and safety evaluation. Here, a method of laser ablation-single particle inductively coupled plasma mass spectrometry (LA-sp-ICP-MS) is shown to have high spatial resolution, sensitivity and accuracy for simultaneous imaging the in situ distribution of particulate Ag (P-Ag) and released ionic Ag (Ion-Ag) in the sub-organs of spleen, liver and kidney after intravenous injection of Ag nanoparticles (50 nm, AgNPs) to mice. Under the optimized parameters of 0.4 J/cm(2) laser fluence on a 30 pm spot with dwell time at 100 mu s, the signals of P-Ag and Ion-Ag in the organic tissues can be easily distinguished from the mass spectra. The method of iterative threshold algorithm has been used to distract the signals of P-Ag and Ion-Ag and separate each other. The resulting images for the first time provide visualized evidence that a considerable amount of P-Ag accumulated in the splenic marginal zone, but widely distributed in the liver parenchyma at 24 h after injection of AgNPs, and in the meantime, obvious amounts of ionic Ag released and distributed in the organs. In addition, the imaging results indicate that the AgNP excretion in the kidney is mainly in ionic forms. The investigation here demonstrates that the developed LA-sp-ICP-MS method with high spatial resolution, sensitivity and visualization capability can become a powerful tool in the clinical context of metallic NPs. (C) 2022 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

In this article, we are dedicated to studying the fractional Schrödinger-Poisson system involving doubly critical exponent. By using the variational method and analytic techniques, we establish the existence of positive ground state solution.

. In this paper, we consider a time-independent fractional equation: where Ω is a smooth bounded domain, s ∈ ( 0 , 1 ) , N > 2 s 0 < q < 1, the coef fi cient functions f and g may change sign. We fi rst obtain the existence of ground state solution by the Nehari method under the combined effect of coef fi cient functions. Then we fi nd the multiplicity of positive solutions by Mountain pass theorem under some stronger conditions, and one of them is a ground state solution.

Due to the overuse of antibiotics, vancomycin resistant enterococci (VRE) has caused serious infections and become more and more difficult to deal with. Herein, we reported a facile one-pot strategy to synthesize copper sulfide nanoparticles using vancomycin (Van) as reductant and capping agent (CuS@Van). The as-prepared CuS@Van nanocomposites presented excellent uniformity in particle size and strong near infrared (NIR) absorbance. Fourier Transform infrared spectroscopy (FTIR) and Energy dispersive spectrometry (EDS) analysis confirmed the successful modification of Van molecules on the surface of CuS@Van nanoparticles. Bacterial TEM images verified the specific binding affinity between CuS@Van and VRE pathogen. CuS@Van also exhibited effective photokilling capability based on a combination of photothermal therapy (PTT) and photodynamic therapy (PDT). Fluorescent bacterial viability staining and bacterial growth curves monitoring were performed to explore the photokilling ablation of CuS@Van against VRE pathogens. The in vitro results indicated that CuS@Van nanocomposites had no antibacterial activity in the dark but displayed satisfying bactericidal effect against VRE pathogens upon the NIR irradiation. Mouse infection assays were also implemented to evaluate in vivo antibacterial photokilling effectiveness. CuS@Van with NIR irradiation showed the highest antibacterial capability and fastest infection regression compared with the control groups. Considering the low cost, easy preparation, good biocompatibility and excellent photokilling capability, CuS@Van nanocomposites will shed bright light on the photokilling ablation of vancomycin-resistant pathogenic bacteria.

Intricate mesoporous biosilica has many biomedical applications as a nanocarrier. However, its potential use in photodynamic therapy (PDT) has received little attention. This work reports the first fabrication of bio-engineered materials by covalently conjugating C-phycocyanin (C-PC), a natural photosensitizer, to biosilica for the PDT of tumor-associated macrophages. The resulting hybrid material showed outstanding photodynamic activity under 620 nm laser irradiation. Furthermore, it enhanced the relatively weak photodynamic effect of C-PC. This study also explored methods of biofunctionalizing biosilica for cancer phototherapy, a new pharmacological application of non-toxic C-PC.

A novel graphene oxide (GO) nanomaterial, which was rapidly and simply synthesised and conjugated with low-molecular-weight chitosan (CS), was used to develop a simple, sensitive GO biosensor system for glucose detection by fluorescence resonance energy transfer. The GO-CS was used to detect low concentrations of glucose based on competitive binding with maltose-binding protein (MBP). The -subunit of recombinant phycocyanin (rPC), which emits far-red fluorescence, was used to label MBP (MBP-rPC). The rPC emission was quenched by binding between GO-CS and MBP. However, in the presence of glucose, GO-CS was out-competed for binding to MBP, leading to rPC fluorescence. Glucose was sensitively and selectively detected with this biosensor, with a linear detection range of 0.1-1 mg glucose/ml. The limit of detection for glucose was approximate to 0.05 mg/ml.

We study a class of Kirchhoff equations $$\begin{aligned} {\left\{ \begin{array}{ll} -\left( a+b\displaystyle \int _{\Omega }|\nabla u|^2\mathrm{d}x\right) \Delta u=\displaystyle \frac{u^{3}}{|x|}+\lambda u^{q},&{}\hbox {in } \Omega , \\ u=0, &{}\hbox {on } \partial \Omega , \end{array}\right. } \end{aligned}$$ where $$\Omega \subset {\mathbb {R}}^{3}$$ is a bounded domain with smooth boundary and $$0\in \Omega $$ , $$a,b,\lambda >0,0"\frac{1}{A_{1}^{2}}$$ ( $$A_{1}>0$$ is the best Sobolev–Hardy constant), using the critical point theorem, infinitely many pairs of distinct solutions are obtained for any $$\lambda >0.$$"