Katarzyna Jurek

New Fluorescence Probes for Biomolecules

Steady state fluorescence measurements have been used for the investigation of interaction between the bovine serum albumin (BSA) and fluorescence probes: 3-hydroxy-2,4-bis[(3-methyl-1,3-benzoxazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ6), 3-hydroxy-2,4-bis[(3-methyl-1,3-benzothiazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ7) and 3-hydroxy-2,4-bis[(1,3,3-trimethyl-1,3-dihydro-2H-indol-2-ylidene)methyl]cyclobut-2-en-1-one (SQ8). The binding constant between bovine serum albumin and squarine dyes has been determined by using both the Benesi-Hildebrand and Stern-Volmer equations. The negative value of free energy change indicates the existence of a spontaneous complexation process of BSA with squarine dyes.

Hemicyanine dyes derived from 2,3,3-trimethyl-3H-indolium as candidates for non-covalent protein probes.

Non-covalent interaction of hemicyanine dyes, derivatives of 2,3,3-trimethyl-3H-indolium with bovine serum albumin has been studied by spectral method. For this purpose, three hemicyanine dyes containing N-(2-carboxyethyl)-2,3,3-trimethyl-3H-indolium moiety were synthesized and their UV/Vis and fluorescence spectra, aggregation, photostability and association with bovine serum albumin were studied. The hemicyanine dyes with 2-ethylcarboxylic group was found to interact with bovine serum albumin, which is probably due to negative charge on the dye molecule at the expense of the carboxylic group and the ability to form hydrogen bonds with albumin.

Squaric acid derivative effects on the kinetics of photopolymerization of different monomers

Systems composed of 1,3-bis(phenylamino)squaraine (photosensitizer) and conventional free radical sources, such as tetramethylammonium n-butyltriphenylborate, diphenyliodonium chloride and diphenyliodonium hexafluorophosphate were used for initiation of photopolymerization occurring via a radical or cationic mechanism. The photopolymerization of 1,6-hexanediol diacrylate (HDDA), pentaerythritol triacrylate (PETA), 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA), cyclohexene oxide (CHO) and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (EPOX) were carried out at 300 nm < λ < 500 nm irradiation. The polymerization kinetics was measured using a differential scanning calorimeter equipped with a high-pressure mercury lamp. The effect of co-initiator structure and type of monomer on the kinetics of the photopolymerization process is also presented here. It was found that the photoredox pairs, consisting of 1,3-bis(phenylamino)squaraine and tetramethylammonium n-butyltriphenylborate or diphenyliodonium salts, initiate radical and cationic polymerization in the UV-Vis light region. The photoinitiating ability of these new photoinitiating systems acting in the UV-Vis light region for initiation of polymerization of acrylates and epoxides was compared with a few commercially used photoinitiating systems.

Visible light-induced polymerization initiated by borate salts of bicationic monochromophoric benzothiazolestyrylium dyes

A series of bicationic monochromophoric hemicyanine dyes based on benzothiazolestyrylium residues were synthesized. The dyeing photoinitiating systems consisting of N-[3-(4-methylpyridino)propyl]-2-(p-substituted styryl)benzothiazolium dihalides as chromophores and n-butyltriphenylborate anion as electron donor were also prepared to achieve an efficient photoinitiators for free-radical polymerization in a visible-light region. The relative photoinitiating efficiencies of novel photoinitiators of acrylate monomers polymerization were evaluated.

The Comparison of the Photoinitiating Ability of the Dyeing Photoinitiating Systems Acting via Photoreducible or Parallel Series Mechanism

Light-induced polymerization reaction is largely encountered in many industrial applications. For example, laser direct imaging, graphics arts, holography, and dental materials require irradiation in the visible light region to benefit from laser technologies or simply to avoid UV damaging effects on skin [1]. The basic idea is to readily transform a liquid resin or a soft film into a solid film upon light exposure to form either a coating as developed in the UV curing area or an image as used in the (laser) imaging area. The starting resin is in fact a formulation that consist in an oligomer, a monomer, a photoinitiating system, and various additives depending on the applications (formulation agents, stabilizers, pigments, fillers, etc.).