Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

Photodynamic therapy(PDT)has been a routine treatment of tumors and some microvascular diseases,but clinically available photosensitizers are still scarce.Among all kinds of photo-sensitizers,hypocellins possess the most characteristics of ideal photosensitizers,such as,high photo-activity but low dark toxicity,fast clearance from tssues.This review is focused on two main topics,drug-delivery problem of hypocrellins and how the environment-sensitive fluorescence of bypecrellins was used for recognition of various biomolecules.Drug-delivery of hypocrellins was mainly achieved in two strategies一preparing the drugdelivery vehicles and finding quantitatively amphiphilic derivatives.Hypocrellin fAuorescence originated from the intramolecular proton transfer is very distinct from other kinds of photosensitizers.Recently,it was proved that quan-titative hypocrellin ftuorescence could not only reoognize various biomolecules,including proteins,polysaocharides and lipids,but also distinguish the specific binding from nonspedifie binding with some kind of biomolecules.Meantime,hypocrellin fluorescence was pH sensitive.It is known that tumor cells or tses have the features of a large amount of lipid,neonatal collagen,over expression of polysaccharides,and lower pH values compared to normal tissues.According to the relative but not absolute specifcity,further studies on quantitative recognition of various biomolecules at a cellular level,may find a new clue to treat tumors by joint usage of photodynamic diagnosis(PDD)and PDT.

Elsinochrome A photosensitizers:Alternative drugs for photodynamic therapy

Photodynamic therapy(PDT)has already been a multifunctional modality for various tumors and nontumorous diseases.However,the development of photosensitizers is relatively delayed,compared with the tremendous progress in laser technology.Elsinochrome A(EA),a per-ylenequinonoid pigment from China,has all the typical advantages of perylenequinones.More-over,singlet oxygen quantum yield of EA is superior to other kinds of photosensitizers and EA could be artifially biosynthesized at present,which make it an alternative candidate for PDT.In.this review,the photophysics,photochemistry,photobiology and chemical or biological syntheses of EA photosensitizers are brielty presented.Besides,the future prospects of EA photosensitizers are also proposed.

A power and thermal management system for long endurance hypersonic vehicle

Due to the pneumatic heating and combustion effect,the scramjet engine of hypersonic vehicle faces high temperature challenge.It is necessary to comprehensively consider its thermal management and power generation together.A new Power and Thermal Management System(PTMS)combined with Supercritical Carbon Dioxide(SCO_(2))closed Brayton cycle and fuel vapor turbine is proposed and discussed in this paper.The new PTMS can meet the cooling requirement of hypersonic vehicle at Mach number 6–7,and avoid the coking and scrapping in the scramjet cooling channels.Compared with the PTMS only based on fuel vapor turbine,the new PTMS utilizes the waste heat of scramjet to generate more electricity.In addition,it can reduce the use of fuel sink for cooling,and the additional weight penalty can be compensated for long endurance hypersonic flight.

Synthesis and energy transfer of model conjugate of phycobilisome rods

The conjugate of R-phycoerythrin (R-PE) and C-phycocyanin (C-PC) was synthesized through a heterobifunctional coupling reagent, N-succinimidyl 3-(2-pyridyldithio) propionate. The molar ratio of R-PE to C-PC was determined by absorption spectra, and the result was 2:1. The energy transfer phenomena were observed from steady-state fluorescence spectra. The calculated result showed that the energy transfer efficiency from R-PE to C-PC was 88%. The energy transfer kinetics was determined by picosecond time-resolved fluorescence spectra. The time constant of energy transfer from R-PE to C-PC was 80 ps, which was much longer than that in the rood of native phycobilisomes.

Kinetics of blue-green light-induced state transition and fluorescence quenching in the wild-type cyanobacterium Synechocystis PCC 6803 and apc D2 and apc F2 mutants

State transition and blue-green light-induced fluorescence quenching are two short-term processes in cyanobacteria. The details of their kinetics and the relationship between these processes have not been elucidated.In this work, these two processes were studied in the wildtype cyanobacterium Synechocystis PCC 6803 cells as well as in apc D-and apc F-mutants by monitoring their timedependent 77 K fluorescence responses to blue-green light(430–540 nm) at a series of intensities ranging from20–800 l E m-2s-1. The lowest light intensity to induce fluorescence quenching in wild-type cells was160 l E m-2s-1under the selected experimental conditions, while state transition took place at the intensities lower than 160 l E m-2s-1at a conservative level, but at variable rates. The quenching level increased at intensities higher than 160 l E m-2s-1, reaching the maximum level at intensities equal to or higher than 200 l E m-2s-1.Fluorescence kinetics indicated that both the length of the induction period and time required to reach the maximum level were functions of light intensity. State transitions as well as fluorescence quenching took place in both wildtype and mutant cells, but might involve different mechanisms.

Structure and function of PBS model complex

A complex of phycobiliproteins, containing phycoerythrocyanin (PEC), C_phycovyanin (C_PC) and allo_phycocyanin (APC) as well as some linker polypeptides, was reconstructed. The absorption and fluorescence spectra of the complex were compared with those of native phycobilisomes (PBS) and the phycobiliproteins. Based on the measured data, it can be concluded that the complex can be taken as a model of PBS and is an entirely functional group for excitation energy transfer step by step from peripheral PEC to APC. The single terminal emitter feature of the complex makes it favorable for clarifying energy transfer pathways and the kinetics in comparison with native PBS. Further research is carried on in the lab.

Model of chromophore coupling in allophycocyanin aggregation

A new model is proposed to study the interaactions among chromphores in APC trimer. Using this model, the electronic transition frequencies are calculated. The results are in good agreement with the experimental.