Femtosecond primary charge separation in Synechocystis sp. PCC 6803 photosystem I

AbstractThe ultrafast (<100fs) conversion of delocalized exciton into charge-separated state between the primary donor P700 (bleaching at 705nm) and the primary acceptor A0 (bleaching at 690nm) in photosystem I (PS I) complexes from Synechocystis sp. PCC 6803 was observed. The data were obtained by application of pump–probe technique with 20-fs low-energy pump pulses centered at 720nm. The earliest absorbance changes (close to zero delay) with a bleaching at 690nm are similar to the product of the absorption spectrum of PS I complex and the laser pulse spectrum, which represents the efficiency spectrum of the light absorption by PS I upon femtosecond excitation centered at 720nm. During the first ∼60fs the energy transfer from the chlorophyll (Chl) species bleaching at 690nm to the Chl bleaching at 705nm occurs, resulting in almost equal bleaching of the two forms with the formation of delocalized exciton between 690-nm and 705-nm Chls. Within the next ∼40fs the formation of a new broad band centered at ∼660nm (attributed to the appearance of Chl anion radical) is observed. This band decays with time constant simultaneously with an electron transfer to A1 (phylloquinone). The subtraction of kinetic difference absorption spectra of the closed (state P700+A0A1) PS I reaction center (RC) from that of the open (state P700A0A1) RC reveals the pure spectrum of the P700+A0− ion–radical pair. The experimental data were analyzed using a simple kinetic scheme: An* →k1 [(PA0)*A1→<100fs P+A0−A1] →k2P+A0A1−, and a global fitting procedure based on the singular value decomposition analysis. The calculated kinetics of transitions between intermediate states and their spectra were similar to the kinetics recorded at 694 and 705nm and the experimental spectra obtained by subtraction of the spectra of closed RCs from the spectra of open RCs. As a result, we found that the main events in RCs of PS I under our experimental conditions include very fast (<100fs) charge separation with the formation of the P700+A0−A1 state in approximately one half of the RCs, the ∼5-ps energy transfer from antenna Chl* to P700A0A1 in the remaining RCs, and ∼25-ps formation of the secondary radical pair P700+A0A1−

АМПЕРОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ ПЕРРЕНАТ-АНИОНА НА МИКРОГРАНИЦЕ МЕЖДУ ДВУМЯ НЕСМЕШИВАЮЩИМИСЯ РАСТВОРАМИ ЭЛЕКТРОЛИТОВ

Voltammetric responses associated with the simple reaction of perrhenate anions transfer across polarized micro-interfaces between two immiscible electrolyte solutions (micro-ITIES) was investigated, and their sensing applications were demonstrated. The micro-ITIES array was formed at polyethylene terephthalate membranes containing a 196 microhole array of radius 10.0±0.1 μm using a femtosecond laser. The characteristics of perrhenate ions transfer at the water/2-nitrophenyloctyl ether interface were first investigated using cyclic voltammetry (CV). CV was used in the estimation of some of the perrhenate anions thermodynamic parameters, such as the formal transfer potential and the Gibbs transfer energy. The technique of alternating current stripping voltammetry (ACSV) was also utilized to improve the sensitivity of the perrhenate anion detection. Under optimized preconcentration and detection conditions, a limit of detection of 0.3 μM with a wide linear dynamic range extending from 1.0 to 100 μM was achieved. The effect of various potential interfering anions on the perrhenate sensor was also investigated and an excellent selectivity over SCN-, I-, NO3-, NO2-, CO32-, SO42-, MoO42-, WO42- and CH3COO- ions was also achieved. This enabled quantitative measurements of rhenium in some mineral raw samples and the data was also validated by comparing with inductively coupled plasma atomic emission spectroscopy.Настоящая работа посвящена изучению простого ионного переноса перренат-иона через поляризуемую микрограницу раздела фаз двух несмешивающихся растворов электролитов (микро-ГРДНРЭ) и применению данного явления для аналитического определения рения. Для создания системы с микро-ГРДНРЭ изготовлена микроперфорированная полимерная мембрана из полиэтилентерефталата , в которой с помощью фемтосекундного лазера проделанмассив из 196 микроотверстий диаметром 10±0.1 мкм. С использованием данной системы методом циклической вольтамперометрии (ЦВА) впервые исследованы первичные характеристики переноса перренат-иона на микрогранице раздела фаз вода/2-нитрофенилоктиловый эфир и определены термодинамические параметры переноса, такие, как формальный потенциал ионного переноса, энергия Гиббса и межфазный коэффициент распределения. Для повышения чувствительности обнаружения перренат-иона применяли также технику инверсионной вольтамперометрии (ИВА). При оптимизированных условиях электрохимического концентрирования и обнаружения достигнут предел обнаружения перренат-иона, равный 0.3 мкМ, с широким линейным динамическим диапазоном от 1.0 до 100 мкМ. Изучено влияние х мешающих ионов на электрохимический отклик перренат-иона, и достигнута отличная селективность по отношению к анионам SCN-, I-, NO3-, NO2-, CO32-, SO42-, MoO42-, WO42- и CH3CO-. Это позволило провести количественное определение рения в некоторых образцах минерального сырья и сравнить полученные данные с результатами, полученными методом атомно-эмиссионной спектроскопии с индуктивно связанной плазмой

Effect of Laser Optoperforation of the Zona Pellucida on Mouse Embryo Development in vitro

Laser operations on cells and embryos are an important field of current photobiology and biophotonics. The high power density of tightly focused laser irradiation provides an efficient impact on matter of cells or embryos. Precise focusing of the laser spot allows strictly controlled perforation of the membrane. The present work was devoted to studying the influence of optoperforation of mammalian embryonic zona pellucida with a tightly focused laser beam with 1.48-µm wavelength on further development of the embryo. Such a laser operation was proposed for application in in vitro fertilization (IVF) practice and intracytoplasmic sperm injection into the oocyte (ICSI). For cultured in vitro oocytes and embryos, the process of natural exiting from the zona pellucida (&quot;hatching&quot;) is often impaired, which decreases probability of implantation and pregnancy The goals of the present work were to determine the influence of different manipulations on development of embryos in vitro until blastocyst formation and on the ISSN 0006-2979, Biochemistry (Moscow), 2015, Vol. 80, No. 6, pp. 769-775. © Pleiades Publishing, Ltd., 2015. Original Russian Text © E. O. Zakharchenko, A. D. Zalessky, A. A. Osychenko, A. S. Krivokharchenko, A. K. Shakhbazyan, A. V. Ryabova, V. A. Nadtochenko, 2015, published in Biokhimiya, 2015 769 * To whom correspondence should be addressed. Abstract-The effect of laser optical perforation of the zona pellucida on the viability and development of mouse embryos has been studied. Operations of zona pellucida thinning and single or double perforation were carried out on 2-cell embryo, morula, and blastocyst stages with a laser pulse (wavelength 1.48 µm, pulse duration 2 ms). Embryo development up to the blastocyst stage and hatching efficiency were statistically analyzed. It was found that 2-cell or morula stage embryo zona pellucida thinning or single perforation did not affect development to the blastocyst stage and number of hatched embryos, but it accelerated embryo hatching compared to control groups one day earlier in vitro. Double optoperforation on 2-cell embryo or morula stage did not significantly affect development to the blastocyst stage, but it strongly decreased the number of hatched embryos. Also, zona pellucida perforation at the blastocyst stage had a negative effect: hatching did not occur after this manipulation. Blastocyst cell number calculation after single zona pellucida perforation at 2-cell and morula stages showed that cell number of hatching or hatched blastocysts did not differ from the same control groups. This fact points out that the laser single optoperforation method is a useful and safe experimental tool that allows further manipulations within the zona pellucida. Effect of Laser Optoperforation of the Zon

Femtosecond Nanosurgery: Laser Enucleation of Chromatin in the Oocyte

A method for cell enucleation by femtosecond laser nanosurgery has been developed. This enucleation technique allows DNA destruction with high precision and low invasiveness, showing good efficiency. The technology of such operations is of great importance in medical and scientific practice.Работа выполнена при поддержке гранта РНФ № 21-75-10155

STUDY OF THE POSSIBILITIES OF USING FEMTOSECOND LASER NANO SURGERY TO OBTAIN PLANT HYBRIDS

Femtosecond laser nanosurgery can be a very convenient selection tool. The method of laser nanosurgery allows working with individual organelles without damaging or killing a cell. Studying the interaction of a laser pulse with a biological material will greatly simplify the selection.Работа выполнена при поддержке гранта Российского фонда фундаментальных исследований 19-53-52007, а также при поддержке Государственного задания ФИЦ ХФ РАН АААА-А19-119012990175-9 с использованием оборудования ЦКП ФИЦ ХФ им. Н. Н. Семенова (№506694)

Femtosecond Nanostructuring of Glass with Optically Trapped Microspheres and Chemical Etching

Laser processing with optically trapped microspheres is a promising tool for nanopatterning at subdiffraction-limited resolution in a wide range of technological and biomedical applications. In this paper, we investigate subdiffraction-limited structuring of borosilicate glass with femtosecond pulses in the near-field of optically trapped microspheres combined with chemical postprocessing. The glass surface was processed by single laser pulses at 780 nm focused by silica microspheres and then subjected to selective etching in KOH, which produced pits in the laser-affected zones (LAZs). Chemical postprocessing allowed obtaining structures with better resolution and reproducibility. We demonstrate production of reproducible pits with diameters as small as 70 nm (λ/11). Complex two-dimensional structures with 100 nm (λ/8) resolution were written on the glass surface point by point with microspheres manipulated by optical tweezers. Furthermore, the mechanism of laser modification underlying selective etching was investigated with mass spectrum analysis. We propose that the increased etching rate of laser-treated glass results from changes in its chemical composition and oxygen deficiency