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1

The DFT study on the electronic structure of boronic acid derivatives and its esters with fructose

Kur K., Kowalska-Baron A., Miller E.

Biotechnology and Food Science

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2018

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Vol. 82, nr 1

29--39

EN

Theoretical investigations are carried out to examine the geometrical structure and parameters of electron transitions to the lowest excited states of two boronic acid derivatives: 3-aminophenylboronic acid and 3-(acetamidomethyl)phenyl boronic acid and its cycling esters with fructose, using the DFT based 6-31 G(d,p) method. The most stable ester isomer of each acid has been selected. Predicted excitation wavelength are shorter (less than 0.5 eV) than experimental ones, what is in a good agreement considering limitations of the DFT method. In case of almost every calculated molecule the analysis of electronic transitions shows that transition S0→S1 involves electron transfer mainly from the HOMO to LUMO orbital.

2

Optical properties of (3-(acetamidomethyl)phenyl)boronic acid and its interactions with selected sugars

Kur K., Przybyt M., Miller E.

Biotechnology and Food Science

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2018

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Vol. 82, nr 1

15--27

EN

(3-(Acetamidomethyl)phenyl)boronic acid (3AAPBA)has at pH 7 absorbance maximum at 270 nm with molar absorbance coefficient 516 M-1cm-1. 3AAPBA exhibits weak fluorescence with maximum at 297 nm and quantum yield 0.062 ± 0.001. Fluorescence decay is monoexponential and the lifetime is 2.05 ± 0.01 ns. Interactions of 3AAPBA with selected sugars were studied by absorbance, steady-state and time-resolved fluorescence measurements. At pH 7 fluorescence of 3AAPBA is quenched only by fructose (with quenching constant 67.9 M-1) and to some extend by galactose. Addition of these two monosaccharides causes also changes of absorbance spectra of 3AAPBA. Acid-base dissociation of free 3AAPBA and its esters with sugars was studied by absorbance and steady-state fluorescence measurements in pH range from 4.5 to 11.00. Esterification of phenylboronic acid derivatives by sugars leads to increased acidity of them. In case of 3AAPBA the obtained values of pK indicate that affinity of studied sugars towards it can be ordered as follows: fructose > galactose > glucose > maltose > lactose > sucrose. At pHs higher than pK the fluorescence decays turn to biexponential with additional shorter component in lifetime which we propose to attribute to anionic form of 3AAPBA or its esters.

3

Force analysis of shoulder joint muscles in the early phase of brain stroke

Starosta M., Kostka J., Miller E.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 3

107--113

EN

Upper limb impairment in the early phase of brain stroke is one of the key problems in rehabilitation. An estimation of muscle force can be a helpful factor for functional improvement after a stroke. The primary goals of this study were to determine the muscles with the lowest force in the affected (A) and non-affected (non-A) upper limb. Moreover, the differences between men and women were compared and these values were correlated with age. Methods: One hundred (n = 35 female, n = 65 male) post-stroke patients met the inclusion criteria. The mean age of the study participants was 66.1 years. Muscle force for external and internal rotators of shoulder was measured with handheld dynamometer. Moreover, the correlation coefficients for differences in muscular force with the patient’s age were estimated. Results: Our study reports that the force of the (A) side in relation to the (non-A) was by 37% weaker. We observed about a 40% decrease in the force of the shoulder’s external rotation (female – 42%; male – 41%) and shoulder’s flexion (by 38% – female; 40% – male). Significant correlations between the muscle force and the age of post-stroke patients were also found. It was concluded that about 4 weeks after the first stroke in the patient’s life, the external rotators are the most affected group of shoulder muscles. Conclusions: Neither sex nor the side of the ischemic brain injury influence the muscle force, whereas age determines both muscle force and muscle force deficits. Older post-stroke patients demonstrate fewer deficits in muscle strength than younger ones.

4

Analysis of upper limb muscle strength in the early phase of brain stroke

Starosta M., Kostka J., Redlicka J., Miller E.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

85--91

EN

Purpose: The aim of this study was to determine the muscles with the lowest strength in nonaffected (non-A) and affected upper limb (A), to assess differences between men and women and to correlate these values with age in patients after stroke. Methods: Sixty hospitalized in Neurorehabilitation Ward patients (40 male, 20 female), 1-2 weeks after stroke, were enrolled to the study. Their age ranged from 50 to 80 years with a mean (sd) of 65,5 (18,7) years. Muscle force values from upper limb muscles were measured using the MicroFet 2 hand-held dynamometer. The results are displayed in newtons [N], mean values of muscular force, effect sizes and confidence intervals displayed as Cohen’s d and 95% CI were determined. Moreover, we made the coefficients correlation for differences in muscular force versus the Rivermead Motor Assessment (RMA) arm section. Results: Strength of (A) upper limb in comparison to (non-A) was 39% weaker. The severely affected muscle groups were the shoulder flexion 41% (women) versus 46% (men); elbow flexion 39% (women) versus 31% (men); wrist extension 36% (women) versus 42% (men). No significant correlations were found between muscle strength results and RMA or age. Conclusions: Muscle force of (A) upper limb after stroke demonstrates 39% decrease. Men show more significant decrease than women (40% vs 35%). Functional assessment in RMA values show the better results in women (4,9 ± 4,1) than men (3,4 ± 3,2).

5

ZnS Cu-doped quantum dots

Ziółczyk P., Miller E., Przybyt M.

Biotechnology and Food Science

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2014

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Vol. 78, nr 1

53--69

EN

The paper presents a survey of literature on the structure and optical properties of ZnS and copper ion-doped ZnS quantum dots. The effect of other metal dopants on the spectral properties of ZnS:Cu quantum dots was also considered. The influence of such parameters as dopant concentration, temperature of the synthesis and compounds which form or modify the additional layer on dots on spectral properties of the quantum dots was described. Examples of application of ZnS:Cu quantum dots are also given.

6

The study of phenylboronic acid optical properties towards creation of a glucose sensor

Kur-Kowalska K., Przybyt M., Miller E.

Biotechnology and Food Science

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2014

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Vol. 78, nr 2

101--110

EN

The article presents influence of pH and glucose concentration on phenylboronic acid (PBA) fluorescence studied by steady-state and time-resolved measurements. Fluorescence of PBA decreases with growing pH. These changes reflected acid-base equilibrium of PBA and allowed to estimate value of pKd as 9.2, which is comparable with literature data. Fluorescence intensity of phenylboronic acid is quenched in presence of glucose. The effect of quenching is more pronounced with increasing pH. At pH 7 quenching can be described by Stern-Volmer equation, at pH 8 and 9 by modified one. The obtained quenching constants are growing with pH increase. The quenching of phenylboronic acid fluorescence by glucose is a static one, which is confirmed by time-resolved measurements. Two lifetimes were found for fluorescence decay of phenylboronic acid. The lifetimes are practically independent on pH and glucose concentration and also fraction of both lifetimes are nearly the same. The obtained Stern-Volmer constants can be interpreted as apparent equilibrium constants of ester formation between acid and glucose.

7

Badania luminescencyjne w żelach silanowych

Miller E.

Wiadomości Chemiczne

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2000

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[Z] 54, 5-6

435-455

EN

Recently, optical sensors (optodes) are very often applied in biomedical sciences and biotechnology in analytical methods which require high sensitivity, selectivity and accuracy. The methods consist in the transmission of analyzed radiation by means of an optical fibre from the source to the sensor, and then of the response from the sensor to the detector also in the form of a light signal at a changed wavelength. A chromophore indicator sensitive to changes in physicochemical properties of an analyzed substance that take place in the reaction system is immobilized on the surface of an optical waveguide. Advantages of the optodes include, among other things, no need to use a reference signal, a very small size and weight, elasticity, a possibility of using distant measurements (up to 1 km) a simple sensor construction and low price. These sensors can be used in the analysis of samples in both liquid and gas phase. This is why they found application in the environmental protection to analyze groundwater and flue gases, in toxicology and to test product quality in the food industry. If an enzyme which catalyzes an appropriate chemical reaction or a co-immobilized enzyme with a sensor transforming changes in the concentration of a substance being formed or decayed as a result of the enzymatic reaction, is immobilized on the fibre surface, then also biologically important compounds such as glucose, fructose, urea, lactate, amino acids, as well as pH can be determined. In the latest studies on the formation of optical materials, especially an organic chromophore immobilizer, researchers often use silane gel which is obtained by the sol-gel technique. In comparison to a high-temperature synthesis of silica glass, the advantage of preparing silane matrices by gelation is that the process requires very mild conditions. This is why an organic compound, e.g. a luminescence probe, introduced to the input sol is not degraded during the gelation process. This paper describes the process of silane gelation in the classical approach according to Flory-Stockmayer's theory and then using the percolation theory. Further on, methods of silane gel formation based on the latest studies are presented. Recent studies on the gelation process based on the excimer spectrum of a classical pyrene probe are discussed. Results of the studies, on the basis of which changes were observed in viscosity and polarity of the fluorophore microenvironment during gelation, are quoted. The changes were measured by the ratio of intensities of respective peaks in the pyrene emission spectrum or fluorescence anisotropy . This paper presents also results of the recent luminescence research of sol-gel transition dynamics using other chromophores, e.g. rhodamine G6, ruthenium complex ,oxazine, 1,4-dihydroxyanthraquinone, 3,3-diethyloxadicarbocyanines and quinine. The silane gel has properties which are important and interesting from the point of view of its application, i.e. transparency, porosity, thermal stability, and ability to form different carrier forms, e.g. powder, film or fibre. So, in the final part of this paper the examples of applications of these carriers in the newest probes, i.e. chemical optical sensors, biochemical optodes, and immunocolumns are presented.