Topotecan (TPT) is used in the treatment of retinoblastoma, the most common malignant intraocular tumor in children. TPT undergoes pH-dependent hydrolysis of the lactone ring to the ring-opened carboxylate form, with the lactone form showing antitumor activity. A selective, and highly sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed for the determination of both forms of TPT in one mobile phase composition in plasma and vitreous humor matrices. The method showed an excellent linear range of 0.375-120 ng/mL for the lactone. For the carboxylate, the linear range was from 0.75 to 120 ng/mL. The matrix effect and the recovery for the lactone ranged from 98.5% to 106.0% in both matrices, for the carboxylate form, it ranged from 94.9% to 101.2%. The dynamics of the transition between TPT lactone and TPT carboxylate were evaluated at different pH environments. The stability of TPT forms was assessed in plasma and vitreous humor at 8 and 37°C and a very fast conversion of lactone to carboxylate form occurred at 37°C in both matrices. The method developed facilitates the investigation of TPT pharmacodynamics and the release kinetics in the development of the innovative local drug delivery systems.
- Klíčová slova
- UHPLC‐MS/MS, anti‐cancer drug topotecan, carboxylate form, lactone form, topotecan stability,
- MeSH
- kyseliny karboxylové chemie analýza MeSH
- laktony * chemie analýza MeSH
- lidé MeSH
- molekulární struktura MeSH
- sklivec * chemie MeSH
- tandemová hmotnostní spektrometrie * MeSH
- topotekan * chemie analýza MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyseliny karboxylové MeSH
- laktony * MeSH
- topotekan * MeSH
The influences of the hydrophilic chain length, morphology and chemical nature have been probed with regard to the adsorption of model proteins onto the surface of soft nanoparticles (crew-cut micelles and polymersomes). The investigations were based on assemblies manufactured from PEOm-b-PLAn (poly(ethylene oxide)-b-poly(lactic acid)), which is a well-established block copolymer platform towards the manufacturing of drug delivery vehicles, and PHPMAm-b-PDPAn (poly([N-(2-hydroxypropyl)]methacrylamide)-b-poly[2-(diisopropylamino)ethyl methacrylate]), which is pH-responsive and therefore potentially able to target damaged cells in slightly acid microenvironments. Besides, protein adsorption onto PHPMA-stabilized nanoparticles has been seldom explored up-to-date. The morphologies were produced using two different approaches (nanoprecipitation and thin-film hydration) and afterwards, the protein-repelling property of the assemblies in model protein environments (BSA - bovine serum albumin, lysozyme and IgG - immunoglobulin G) was evaluated. We report that, regardless the morphology, PHPMA35-b-PDPA42 block copolymer assemblies are highly stable with negligible protein binding. On the other hand, PEOm-b-PLAn nanostructures are susceptible to protein adsorption and the phenomenon is protein-dependent. The nanoparticles are more susceptible to adsorption of the model positively charged biomacromolecule (lysozyme). The adsorption phenomenon is thermodynamically complex with simultaneous endothermic and exothermic processes involved. Although the experimental data highlight that qualitatively the morphology plays negligible effects on the event, fluorescence spectroscopy measurements evidenced that the binding is stronger onto the surface of nanoparticles stabilized by shorter hydrophilic shells. Nevertheless, the adsorption does not affect the secondary structure of the model proteins as confirmed by circular dichroism spectroscopy. Overall, by comparing soft nanoparticles stabilized by PEO and PHPMA, the latter is herein proved to be a better choice towards the manufacturing of non-fouling structures (either core-shell or hollow spheres) where even a reasonably short hydrophilic chain confers outstanding protein-repelling feature.
- MeSH
- adsorpce MeSH
- akrylamidy chemie MeSH
- nanočástice chemie MeSH
- polymery chemie MeSH
- povrchové vlastnosti MeSH
- proteiny chemie MeSH
- termodynamika MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- akrylamidy MeSH
- N-(2-hydroxypropyl)methacrylamide MeSH Prohlížeč
- polymery MeSH
- proteiny MeSH
An antibody mimetic known as Fab-PEG-Fab (FpF) is a stable bivalent molecule that may have some potential therapeutic advantages over IgG antibodies due to differences in their binding kinetics as determined by surface plasmon resonance. Here we describe the thermodynamic binding properties to vascular endothelial growth factor (VEGF) of the FpF antibody mimetics derived from bevacizumab and ranibizumab. Bevacizumab is an IgG antibody and ranibizumab is an antibody fragment (Fab). Both are used clinically to target VEGF to inhibit angiogenesis. FpFbeva displayed comparable binding affinity (KD) and binding thermodynamics (ΔH = -25.7 kcal mole-1 and ΔS = 14 kcal mole-1) to bevacizumab (ΔH = -25 kcal mole-1, ΔS = 13.3 kcal mole-1). FpFrani interactions with VEGF were characterised by large favourable enthalpy (ΔH = -42 kcal mole-1) and unfavourable entropy (ΔS = 31 kcal mole-1) changes compared to ranibizumab (ΔH = -18.5 kcal mole-1 and ΔS = 6.7 kcal mole-1), which being a Fab, is mono-valent. A large negative entropy change resulting in binding of bivalent FpF to homodimer VEGF might be due to the conformational change of the flexible regions of the FpF upon ligand binding. Mono-valent Fab (i.e. ranibizumab or the Fab derived from bevacizumab) displayed a larger degree of freedom (smaller unfavourable entropy) upon binding to homodimer VEGF. Our report describes the first comprehensive enthalpy and entropy compensation analysis for FpF antibody mimetics. While the FpFs displayed similar thermodynamics and binding affinity to the full IgG (i.e. bevacizumab), their enhanced protein stability, slower dissociation rate and lack of Fc effector functions could make FpF a potential next-generation therapy for local tissue-targeted indications.
- Publikační typ
- časopisecké články MeSH
α-synuclein amyloid fibrils are found in surviving neurons of Parkinson's disease affected patients, but the role they play in the disease development is still under debate. A growing number of evidences points to soluble oligomers as the major cytotoxic species, while insoluble fibrillar aggregates could even play a protection role. In this work, we investigate α-synuclein fibrils dissociation induced at high pressure by means of Small Angle X-ray Scattering and Fourier Transform Infrared Spectroscopy. Fibrils were produced from wild type α-synuclein and two familial mutants, A30P and A53T. Our results enlighten the different reversible nature of α-synuclein fibrils fragmentation at high pressure and suggest water excluded volumes presence in the fibrils core. Wild type and A30P species stabilized at high pressure are highly amyloidogenic and quickly re-associate into fibrils upon decompression, while A53T species shows a partial reversibility of the process likely due to the presence of an intermediate oligomeric state stabilized at high pressure. The amyloid fibrils dissociation process is here suggested to be associated to a negative activation volume, supporting the notion that α-synuclein fibrils are in a high-volume and high-compressibility state and hinting at the presence of a hydration-mediated activated state from which dissociation occurs.
- Klíčová slova
- Amyloid, FTIR, High-pressure, SAXS, α-synuclein,
- MeSH
- alfa-synuklein chemie genetika metabolismus MeSH
- amyloid chemie genetika metabolismus MeSH
- bodová mutace MeSH
- difrakce rentgenového záření MeSH
- lidé MeSH
- maloúhlový rozptyl MeSH
- Parkinsonova nemoc genetika metabolismus MeSH
- rozpustnost MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- tlak MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alfa-synuklein MeSH
- amyloid MeSH
In the present work, we have studied for the first time the combined effect of both sonication and precipitation pH on the structure of amorphous zirconia gels synthesized from zirconium(IV) propoxide. The techniques of small-angle neutron and X-ray scattering (SANS and SAXS) and low temperature nitrogen adsorption provided the integral data on the changes in the microstructure and mesostructure of these materials caused by ultrasonic (US) treatment. Amorphous ZrO2·xH2O synthesized under ultrasonic treatment was found to possess a very structured surface, characterized by the surface fractal dimension 2.9-3.0, compared to 2.3-2.5 for the non US-assisted synthesis, and it was also found to possess a higher specific surface area, while the sizes of the primary particles remain unchanged.
- Klíčová slova
- Fractals, Mesostructure, Small-angle X-ray scattering, Small-angle neutron scattering, Ultrasonication, Zirconia,
- Publikační typ
- časopisecké články MeSH
Novel star polymer-doxorubicin conjugates designed for passive tumor targeting have been developed and their potential for treatment of cancer has been investigated. In the present study the synthesis, physico-chemical characterization, drug release, bio-distribution and preliminary data of in vivo efficacy of the conjugates are described. In the water-soluble conjugates the core of a molecule formed by poly(amido amine) (PAMAM) dendrimers was grafted with semitelechelic N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers bearing doxorubicin (Dox) attached by hydrazone bonds enabling intracellular pH-controlled hydrolytic drug release, or by GFLG sequence susceptible to enzymatic degradation. The controlled synthesis utilizing semitelechelic copolymer precursors facilitated preparation of polymer conjugates in a broad range of molecular weights (1.1-3.0·10(5) g/mol). In contrast to free drug or linear conjugates the star polymer-Dox conjugates exhibited prolonged blood circulation and enhanced tumor accumulation in tumor-bearing mice indicating important role of the EPR effect. The star polymer-Dox conjugates showed significantly higher anti-tumor activity in vivo than Dox?HCl or its linear or graft polymer conjugates, if treated with a single dose 15 or 5 mg Dox eq./kg. Method of tumor initialization (acute or chronic experimental tumor models) significantly influenced effectiveness of the treatment with much lower success in treatment of mice bearing chronic tumors.
- MeSH
- akrylamidy chemie MeSH
- antibiotika antitumorózní aplikace a dávkování chemie farmakokinetika MeSH
- dendrimery chemie MeSH
- doxorubicin aplikace a dávkování chemie farmakokinetika MeSH
- koncentrace vodíkových iontů MeSH
- léky s prodlouženým účinkem MeSH
- lymfom T-buněčný farmakoterapie patologie MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nosiče léků chemie MeSH
- rozpustnost MeSH
- systémy cílené aplikace léků * MeSH
- tkáňová distribuce MeSH
- voda chemie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- akrylamidy MeSH
- antibiotika antitumorózní MeSH
- dendrimery MeSH
- doxorubicin MeSH
- léky s prodlouženým účinkem MeSH
- N-(2-hydroxypropyl)methacrylamide MeSH Prohlížeč
- nosiče léků MeSH
- PAMAM Starburst MeSH Prohlížeč
- voda MeSH
