Adam Buczkowski - Academia.edu (original) (raw)
Papers by Adam Buczkowski
Scientific reports, Mar 11, 2024
The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their inter... more The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their interactions with objects on their way to the target. In the present work, we investigated the interaction of a new class of carbosilane dendrimers functionalized with polyphenolic and caffeic acid residues with human serum albumin, which is the most abundant blood protein. The addition of dendrimers to albumin solution decreased the zeta potential of albumin/dendrimer complexes as compared to free albumin, increased density of the fibrillary form of albumin, shifted fluorescence spectrum towards longer wavelengths, induced quenching of tryptophan fluorescence, and decreased ellipticity of circular dichroism resulting from a reduction in the albumin α-helix for random coil structural form. Isothermal titration calorimetry showed that, on average, one molecule of albumin was bound by 6-10 molecules of dendrimers. The zeta size confirmed the binding of the dendrimers to albumin. The interaction of dendrimers and albumin depended on the number of caffeic acid residues and polyethylene glycol modifications in the dendrimer structure. In conclusion, carbosilane polyphenolic dendrimers interact with human albumin changing its structure and electrical properties. However, the consequences of such interaction for the efficacy and side effects of these dendrimers as drug/nucleic acid delivery system requires further research.
Journal of Molecular Liquids, 2020
Abstract Mianserin hydrochloride (MIA), a drug, which belongs to a group of tetracyclic, noradren... more Abstract Mianserin hydrochloride (MIA), a drug, which belongs to a group of tetracyclic, noradrenergic and specific serotonergic antidepressants, is one of the commonly used psychotropic drugs. Despite its important uses and having a number of other potential utilizations, MIA has quite significant side effects on a patient health, including some cytotoxicity. The MIA toxicity could be reduced by drug encapsulation inside a non-toxic carrier, like β-cyclodextrin molecules (β-CD). Cyclodextrins are cone shaped supramolecules with hydrophobic interior, where hydrophobic parts of molecule can be included, and with hydrophilic rims consisting of primary and secondary hydroxyl groups, which can interact with water molecules. This study investigated the characteristic and mechanism for interaction of MIA with β-CD, and evaluated the effects of complexation on MIA cytotoxicity. Chemical shift differences for protons in mianserin hydrochloride and β-cyclodextrin molecules, induced by the formation of the inclusion complexes, have been determined by proton nuclear magnetic resonance spectroscopy. The other chemical properties of mianserin hydrochloride in aqueous solution in the presence of β-cyclodextrin has been examined at 298.15 K with the use of mass spectrometry and circular dichroism. The results showed that interaction of MIA with β-CD occurred through incorporation of MIA aromatic rings inside probably more than one β-CD molecules. The effects of β-cyclodextrin, mianserin hydrochloride and complexes thereof on the viability of Chinese hamster cells were investigated in order to estimate the cytotoxicity of the drug. The viability of B14 cells treated with MIA + β-CD is higher than with MIA and the protective effect is the highest for complexes of MIA:β-CD in a 1:4 ratio.
Journal of Thermal Analysis and Calorimetry, Apr 17, 2018
Studies on the interactions between cucurbituril Q7 and gemcitabine (Gem) hydrochloride in water ... more Studies on the interactions between cucurbituril Q7 and gemcitabine (Gem) hydrochloride in water were carried out using isothermal titration calorimetry (ITC) and electrospray ionization-mass spectrometry (ESI-MS). According to ITC and ESI-MS, the formation of this complex occurs in both the solution containing excess gemcitabine and the solution containing excess cucurbituril Q7. ITC results confirm the formation of a thermodynamically stable supramolecular complex with stoichiometry 1:1. The inclusion mechanism of Gem inside the cucurbituril macromolecule is spontaneous (DG\0). This process is exothermic (DH\0) and is characterized by the loss of entropy (DS\0).
International Journal of Secondary Metabolite, Jul 14, 2014
Poly(amidoamine) dendrimers (PAMAM) are polymeric macromolecules that can find their use as carri... more Poly(amidoamine) dendrimers (PAMAM) are polymeric macromolecules that can find their use as carriers of small ligand molecules such as cosmetics and drugs. 5- Fluorouracil is a potent oncological drug, whose usage is limited because of its relatively high toxicity.The surface and internal layer groups in PAMAM dendrimer belonging to the third (G3) generation create an open-type structure, which facilitate small ligand molecules to bind with them.The formation equilibrium of PAMAM G3 dendrimer complex with an oncologic drug such as 5 fluorouracil (FU) in water at room temperature was examined. Using the results of the drug solubility in dendrimer solutions, the maximal number of drug molecules in the dendrimer-drug complex was evaluated. Solubility results show that PAMAM G3 dendrimer can transfer tens 5 fluorouracil molecules in aqueous solution.This research work was funded from the Polish budget appropriations for science in the years 2013-2015, project number IP2012 022372.
European Journal of Medicinal Chemistry
Spectroscopic examinations of flutamide solubility and 1 H NMR measurements (flutamide and cycloc... more Spectroscopic examinations of flutamide solubility and 1 H NMR measurements (flutamide and cyclocreatine) show that in aqueous solutions, molecules of the antitumor drugs tested stronger interact with macromolecules of cationic PAMAM G5-NH 2 dendrimer compared with hydroxyl PAMAM G5-OH dendrimer. Solubility measurements show that cationic PAMAM G5-NH 2 dendrimer macromolecules combine more ( n 1.40 ± 0.16) flutamide molecules compared with PAMAM-OH G5 ( n 0.45 ± 0.15). The results of 1 H NMR spectroscopic measurements imply that the combination of flutamide with both dendrimers proceeds with the macromolecule functional groups placed on their surface. Introduction Polyamideamine dendrimers (PAMAM) constitute a subgroup of tree-like shape oligomers synthesized in the eighties by Donald Tomalia [1-3]. Commercially available PAMAM dendrimers of integer generations with an ethylenediamine core are terminated with the terminal amino groups: CH 2 CH 2 CONHCH 2 CH 2 NH 2 (in the case of ...
Scientific Reports, 2021
The aim of this study was to evaluate the nature and mechanisms of interaction between HIV peptid... more The aim of this study was to evaluate the nature and mechanisms of interaction between HIV peptide/dendrimer complexes (dendriplex) and artificial lipid membranes, such as large unilayered vesicles (LUV) and lipid monolayers in the air–water interface. Dendriplexes were combined as one of three HIV-derived peptides (Gp160, P24 and Nef) and one of two cationic phosphorus dendrimers (CPD-G3 and CPD-G4). LUVs were formed of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) or of a mixture of DMPC and dipalmitoyl-phosphatidylglycerol (DPPG). Interactions between dendriplexes and vesicles were characterized by dynamic light scattering (DLS), fluorescence anisotropy, differential scanning calorimetry (DSC) and Langmuir–Blodgett methods. The morphology of formed systems was examined by transmission electron microscopy (TEM). The results suggest that dendriplexes interact with both hydrophobic and hydrophilic regions of lipid bilayers. The interactions between dendriplexes and negativ...
International Journal of Pharmaceutics, 2016
The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR... more The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate spontaneous (ΔG<0) bonding of 5-fluorouracil by both cationic PAMAM G3-NH2 dendrimer and hydroxyl PAMAM G3-OH dendrimer in aqueous solutions. PAMAM G3-NH2 dendrimer bonds about n= 25±8 drug molecules. Some of them n1= 5±1 are bonded by terminal amine groups with equilibrium constant K1= 3890±930, while the remaining ones n2= 24 ±3 are bonded by amide groups with equilibrium constant K2= 110±30. Hydroxyl PAMAM G3-OH dendrimer bonds n=6.0±1.6 molecules of 5-fluorouracil through tertiary amine groups with equilibrium constant K= 65±10. The parameters of bonding 5-fluorouracil by PAMAM G3-NH2 and G3-OH dendrimer were compared with those of bonding this drug by the macromolecules of PAMAM of generations G4-NH2, G5-NH2 and G5-OH.
International Journal of Pharmaceutics, 2015
The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR... more The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate exothermic (ΔH<0) and spontaneous (ΔG<0) combination of an antitumor drug, 5-fluorouracil, by both cationic PAMAM G5-NH2 dendrimer and its hydroxyl analog PAMAM G5-OH in aqueous solutions at room temperature. PAMAM G5-NH2 dendrimer combines about 70 molecules of the drug with equilibrium constant K≅300, which is accompanied by an increase in the system order (ΔS<0). Hydroxyl dendrimer, PAMAM G5-OH, combines about 14 molecules of 5-fluorouracil with equilibrium constant K≅100. This process is accompanied by an increase in the system disorder (ΔS>0).
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Interactions between electromagnetic radiation and the side substituents of aromatic amino acids ... more Interactions between electromagnetic radiation and the side substituents of aromatic amino acids are widely used in the biochemical studies on proteins and their interactions with ligand molecules. That is why the aim of our study was to characterize the formation of complexes between PAMAM-NH2 G4 dendrimer and L-α-tryptophan and L-α-tyrosine in water. The number of L-α-tryptophan and L-α-tyrosine molecules attached to the macromolecule of PAMAM-NH2 G4 dendrimer and the formation constants of the supramolecular complexes formed have been determined. The macromolecule of PAMAM-NH2 G4 can reversibly attach about 25 L-α-tryptophan molecules with equilibrium constant K equal to 130±30 and 24±6 L-α-tyrosine molecules. This characterization was deduced on the basis of the solubility measurements of the amino acids in aqueous dendrimer solutions, the (1)H NMR and 2D-NOESY measurements of the dendrimer solutions with the amino acids, the equilibrium dialysis and the circular dichroism measurements of the dendrimer aqueous solutions with L-α-tryptophan. Our date confirmed the interactions of L-α-tryptophan and L-α-tyrosine with the dendrimer in aqueous solution and indicated a reversible character of the formed complexes.
Journal of Molecular Liquids, 2013
Interactions between PAMAM-NH 2 G4 dendrimer and paracetamol in aqueous solutions were examined b... more Interactions between PAMAM-NH 2 G4 dendrimer and paracetamol in aqueous solutions were examined by UV spectroscopy, equilibrium dialysis, 1 H NMR spectroscopy and calorimetric techniques. The results of equilibrium dialysis show that PAMAM-NH 2 G4 dendrimer can combine 18 paracetamol molecules with equilibrium constant K = 280 ± 40. Using the method of calorimetric titration (ITC), it has been found that the paracetamol addition to dendrimer is an exothermic process. Based on the model of two active sites in a dendrimer molecule, the results of equilibrium dialyses were described and it was calculated that a molecule of dendrimer has about three sites strongly combining paracetamol (K 1 = 2100 ± 670) and about 15 sites that weakly combine the drug (K 2 = 130 ± 30). The measurements of paracetamol solubility in aqueous solutions of PAMAM-NH 2 G4 dendrimer confirm the paracetamol addition to this dendrimer.
Journal of Molecular Liquids, 2012
ABSTRACT Polyamidoamine dendrimer (PAMAM-NH2 G4) complex with 5-fluorouracil, an oncological drug... more ABSTRACT Polyamidoamine dendrimer (PAMAM-NH2 G4) complex with 5-fluorouracil, an oncological drug, was investigated by the technique of equilibrium dialysis at temperatures of 20 °C and 45 °C. The results obtained were worked out by means of the modified model of two sets of active sites proposed by Bobrovnik. Based on the analysis of the results obtained, it was calculated that at a temperature of 20 °C the dendrimer molecule can bind about 12 molecules of the ligand with equilibrium constant K1 ≅ 5600 and about 37 molecules with equilibrium constant K2 ≅ 150. At a temperature of 45 °C the number of the dendrimer binding sites is similar but the equilibrium constants of binding 5-fluorouracil with both sets of active sites are clearly lower (K1 ≅ 1820, K2 ≅ 70). The saturation of both the sets of active sites is of an exothermic character.
![Research paper thumbnail of Doubly or triply protonated? Complexes of cucurbit[n]urils (n = 6–8) with a tripodal ligand tris(2-aminoethyl)amine (TREN)](https://attachments.academia-assets.com/87455319/thumbnails/1.jpg)
](Journal of Molecular Liquids, 2021
Abstract Binding interactions between a tripodal ligand tris(2-aminoethyl)amine (TREN) and a seri... more Abstract Binding interactions between a tripodal ligand tris(2-aminoethyl)amine (TREN) and a series of cucurbit[n]urils (n = 6–8) in aqueous (H2O or D2O) formic acid solutions were investigated by electrospray mass spectrometry (ESI MS), isothermal titration calorimetry (ITC) and NMR titration. DFT calculations were also performed to rationalize the experimental findings. ESI MS data indicate that the studied cucurbiturils bind TREN amine forming two types of adducts of a 1:1 stoichiometry. Dipositive adducts are formed by CB6 and CB7 homologues, while tripositive adducts are formed by CB7 and CB8 homologues. DFT calculations show that the type of the formed adduct is connected with the dimensions of the cucurbituril portal. The results of NMR and ITC measurements confirm that all three CBn homologues (n = 6–8) bind TREN ligands spontaneously in the liquid phase. According ITC results the CB7 homologue binds this amine more strongly than the CB6 and CB8 homologues.
Journal of Molecular Liquids
Abstract We performed calorimetric titration (ITC) measurements of aqueous albendazole solutions ... more Abstract We performed calorimetric titration (ITC) measurements of aqueous albendazole solutions with aqueous β-cyclodextrin solutions. The obtained results were used to determine the enthalpy and entropy of the drug–β-cyclodextrin interaction, the stoichiometry of the resulting inclusion complex and its formation constant. Using the UV spectrophotometer, we determined the solubility of albendazole in water, as well as the increase of the drug solubility driven by the increase of β-cyclodextrin concentration. Biological studies carried out on mouse cultures confirmed an increase of the albendazole–β-cyclodextrin complex bioavailability, as compared to the uncomplexed drug.
Journal of Molecular Liquids
Journal of Molecular Liquids
The Journal of Chemical Thermodynamics
Journal of Molecular Liquids
Scientific reports, Mar 11, 2024
The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their inter... more The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their interactions with objects on their way to the target. In the present work, we investigated the interaction of a new class of carbosilane dendrimers functionalized with polyphenolic and caffeic acid residues with human serum albumin, which is the most abundant blood protein. The addition of dendrimers to albumin solution decreased the zeta potential of albumin/dendrimer complexes as compared to free albumin, increased density of the fibrillary form of albumin, shifted fluorescence spectrum towards longer wavelengths, induced quenching of tryptophan fluorescence, and decreased ellipticity of circular dichroism resulting from a reduction in the albumin α-helix for random coil structural form. Isothermal titration calorimetry showed that, on average, one molecule of albumin was bound by 6-10 molecules of dendrimers. The zeta size confirmed the binding of the dendrimers to albumin. The interaction of dendrimers and albumin depended on the number of caffeic acid residues and polyethylene glycol modifications in the dendrimer structure. In conclusion, carbosilane polyphenolic dendrimers interact with human albumin changing its structure and electrical properties. However, the consequences of such interaction for the efficacy and side effects of these dendrimers as drug/nucleic acid delivery system requires further research.
Journal of Molecular Liquids, 2020
Abstract Mianserin hydrochloride (MIA), a drug, which belongs to a group of tetracyclic, noradren... more Abstract Mianserin hydrochloride (MIA), a drug, which belongs to a group of tetracyclic, noradrenergic and specific serotonergic antidepressants, is one of the commonly used psychotropic drugs. Despite its important uses and having a number of other potential utilizations, MIA has quite significant side effects on a patient health, including some cytotoxicity. The MIA toxicity could be reduced by drug encapsulation inside a non-toxic carrier, like β-cyclodextrin molecules (β-CD). Cyclodextrins are cone shaped supramolecules with hydrophobic interior, where hydrophobic parts of molecule can be included, and with hydrophilic rims consisting of primary and secondary hydroxyl groups, which can interact with water molecules. This study investigated the characteristic and mechanism for interaction of MIA with β-CD, and evaluated the effects of complexation on MIA cytotoxicity. Chemical shift differences for protons in mianserin hydrochloride and β-cyclodextrin molecules, induced by the formation of the inclusion complexes, have been determined by proton nuclear magnetic resonance spectroscopy. The other chemical properties of mianserin hydrochloride in aqueous solution in the presence of β-cyclodextrin has been examined at 298.15 K with the use of mass spectrometry and circular dichroism. The results showed that interaction of MIA with β-CD occurred through incorporation of MIA aromatic rings inside probably more than one β-CD molecules. The effects of β-cyclodextrin, mianserin hydrochloride and complexes thereof on the viability of Chinese hamster cells were investigated in order to estimate the cytotoxicity of the drug. The viability of B14 cells treated with MIA + β-CD is higher than with MIA and the protective effect is the highest for complexes of MIA:β-CD in a 1:4 ratio.
Journal of Thermal Analysis and Calorimetry, Apr 17, 2018
Studies on the interactions between cucurbituril Q7 and gemcitabine (Gem) hydrochloride in water ... more Studies on the interactions between cucurbituril Q7 and gemcitabine (Gem) hydrochloride in water were carried out using isothermal titration calorimetry (ITC) and electrospray ionization-mass spectrometry (ESI-MS). According to ITC and ESI-MS, the formation of this complex occurs in both the solution containing excess gemcitabine and the solution containing excess cucurbituril Q7. ITC results confirm the formation of a thermodynamically stable supramolecular complex with stoichiometry 1:1. The inclusion mechanism of Gem inside the cucurbituril macromolecule is spontaneous (DG\0). This process is exothermic (DH\0) and is characterized by the loss of entropy (DS\0).
International Journal of Secondary Metabolite, Jul 14, 2014
Poly(amidoamine) dendrimers (PAMAM) are polymeric macromolecules that can find their use as carri... more Poly(amidoamine) dendrimers (PAMAM) are polymeric macromolecules that can find their use as carriers of small ligand molecules such as cosmetics and drugs. 5- Fluorouracil is a potent oncological drug, whose usage is limited because of its relatively high toxicity.The surface and internal layer groups in PAMAM dendrimer belonging to the third (G3) generation create an open-type structure, which facilitate small ligand molecules to bind with them.The formation equilibrium of PAMAM G3 dendrimer complex with an oncologic drug such as 5 fluorouracil (FU) in water at room temperature was examined. Using the results of the drug solubility in dendrimer solutions, the maximal number of drug molecules in the dendrimer-drug complex was evaluated. Solubility results show that PAMAM G3 dendrimer can transfer tens 5 fluorouracil molecules in aqueous solution.This research work was funded from the Polish budget appropriations for science in the years 2013-2015, project number IP2012 022372.
European Journal of Medicinal Chemistry
Spectroscopic examinations of flutamide solubility and 1 H NMR measurements (flutamide and cycloc... more Spectroscopic examinations of flutamide solubility and 1 H NMR measurements (flutamide and cyclocreatine) show that in aqueous solutions, molecules of the antitumor drugs tested stronger interact with macromolecules of cationic PAMAM G5-NH 2 dendrimer compared with hydroxyl PAMAM G5-OH dendrimer. Solubility measurements show that cationic PAMAM G5-NH 2 dendrimer macromolecules combine more ( n 1.40 ± 0.16) flutamide molecules compared with PAMAM-OH G5 ( n 0.45 ± 0.15). The results of 1 H NMR spectroscopic measurements imply that the combination of flutamide with both dendrimers proceeds with the macromolecule functional groups placed on their surface. Introduction Polyamideamine dendrimers (PAMAM) constitute a subgroup of tree-like shape oligomers synthesized in the eighties by Donald Tomalia [1-3]. Commercially available PAMAM dendrimers of integer generations with an ethylenediamine core are terminated with the terminal amino groups: CH 2 CH 2 CONHCH 2 CH 2 NH 2 (in the case of ...
Scientific Reports, 2021
The aim of this study was to evaluate the nature and mechanisms of interaction between HIV peptid... more The aim of this study was to evaluate the nature and mechanisms of interaction between HIV peptide/dendrimer complexes (dendriplex) and artificial lipid membranes, such as large unilayered vesicles (LUV) and lipid monolayers in the air–water interface. Dendriplexes were combined as one of three HIV-derived peptides (Gp160, P24 and Nef) and one of two cationic phosphorus dendrimers (CPD-G3 and CPD-G4). LUVs were formed of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) or of a mixture of DMPC and dipalmitoyl-phosphatidylglycerol (DPPG). Interactions between dendriplexes and vesicles were characterized by dynamic light scattering (DLS), fluorescence anisotropy, differential scanning calorimetry (DSC) and Langmuir–Blodgett methods. The morphology of formed systems was examined by transmission electron microscopy (TEM). The results suggest that dendriplexes interact with both hydrophobic and hydrophilic regions of lipid bilayers. The interactions between dendriplexes and negativ...
International Journal of Pharmaceutics, 2016
The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR... more The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate spontaneous (ΔG<0) bonding of 5-fluorouracil by both cationic PAMAM G3-NH2 dendrimer and hydroxyl PAMAM G3-OH dendrimer in aqueous solutions. PAMAM G3-NH2 dendrimer bonds about n= 25±8 drug molecules. Some of them n1= 5±1 are bonded by terminal amine groups with equilibrium constant K1= 3890±930, while the remaining ones n2= 24 ±3 are bonded by amide groups with equilibrium constant K2= 110±30. Hydroxyl PAMAM G3-OH dendrimer bonds n=6.0±1.6 molecules of 5-fluorouracil through tertiary amine groups with equilibrium constant K= 65±10. The parameters of bonding 5-fluorouracil by PAMAM G3-NH2 and G3-OH dendrimer were compared with those of bonding this drug by the macromolecules of PAMAM of generations G4-NH2, G5-NH2 and G5-OH.
International Journal of Pharmaceutics, 2015
The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR... more The results of spectroscopic measurements (increase in solubility, equilibrium dialysis, (1)H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate exothermic (ΔH<0) and spontaneous (ΔG<0) combination of an antitumor drug, 5-fluorouracil, by both cationic PAMAM G5-NH2 dendrimer and its hydroxyl analog PAMAM G5-OH in aqueous solutions at room temperature. PAMAM G5-NH2 dendrimer combines about 70 molecules of the drug with equilibrium constant K≅300, which is accompanied by an increase in the system order (ΔS<0). Hydroxyl dendrimer, PAMAM G5-OH, combines about 14 molecules of 5-fluorouracil with equilibrium constant K≅100. This process is accompanied by an increase in the system disorder (ΔS>0).
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Interactions between electromagnetic radiation and the side substituents of aromatic amino acids ... more Interactions between electromagnetic radiation and the side substituents of aromatic amino acids are widely used in the biochemical studies on proteins and their interactions with ligand molecules. That is why the aim of our study was to characterize the formation of complexes between PAMAM-NH2 G4 dendrimer and L-α-tryptophan and L-α-tyrosine in water. The number of L-α-tryptophan and L-α-tyrosine molecules attached to the macromolecule of PAMAM-NH2 G4 dendrimer and the formation constants of the supramolecular complexes formed have been determined. The macromolecule of PAMAM-NH2 G4 can reversibly attach about 25 L-α-tryptophan molecules with equilibrium constant K equal to 130±30 and 24±6 L-α-tyrosine molecules. This characterization was deduced on the basis of the solubility measurements of the amino acids in aqueous dendrimer solutions, the (1)H NMR and 2D-NOESY measurements of the dendrimer solutions with the amino acids, the equilibrium dialysis and the circular dichroism measurements of the dendrimer aqueous solutions with L-α-tryptophan. Our date confirmed the interactions of L-α-tryptophan and L-α-tyrosine with the dendrimer in aqueous solution and indicated a reversible character of the formed complexes.
Journal of Molecular Liquids, 2013
Interactions between PAMAM-NH 2 G4 dendrimer and paracetamol in aqueous solutions were examined b... more Interactions between PAMAM-NH 2 G4 dendrimer and paracetamol in aqueous solutions were examined by UV spectroscopy, equilibrium dialysis, 1 H NMR spectroscopy and calorimetric techniques. The results of equilibrium dialysis show that PAMAM-NH 2 G4 dendrimer can combine 18 paracetamol molecules with equilibrium constant K = 280 ± 40. Using the method of calorimetric titration (ITC), it has been found that the paracetamol addition to dendrimer is an exothermic process. Based on the model of two active sites in a dendrimer molecule, the results of equilibrium dialyses were described and it was calculated that a molecule of dendrimer has about three sites strongly combining paracetamol (K 1 = 2100 ± 670) and about 15 sites that weakly combine the drug (K 2 = 130 ± 30). The measurements of paracetamol solubility in aqueous solutions of PAMAM-NH 2 G4 dendrimer confirm the paracetamol addition to this dendrimer.
Journal of Molecular Liquids, 2012
ABSTRACT Polyamidoamine dendrimer (PAMAM-NH2 G4) complex with 5-fluorouracil, an oncological drug... more ABSTRACT Polyamidoamine dendrimer (PAMAM-NH2 G4) complex with 5-fluorouracil, an oncological drug, was investigated by the technique of equilibrium dialysis at temperatures of 20 °C and 45 °C. The results obtained were worked out by means of the modified model of two sets of active sites proposed by Bobrovnik. Based on the analysis of the results obtained, it was calculated that at a temperature of 20 °C the dendrimer molecule can bind about 12 molecules of the ligand with equilibrium constant K1 ≅ 5600 and about 37 molecules with equilibrium constant K2 ≅ 150. At a temperature of 45 °C the number of the dendrimer binding sites is similar but the equilibrium constants of binding 5-fluorouracil with both sets of active sites are clearly lower (K1 ≅ 1820, K2 ≅ 70). The saturation of both the sets of active sites is of an exothermic character.
Journal of Molecular Liquids, 2021
Abstract Binding interactions between a tripodal ligand tris(2-aminoethyl)amine (TREN) and a seri... more Abstract Binding interactions between a tripodal ligand tris(2-aminoethyl)amine (TREN) and a series of cucurbit[n]urils (n = 6–8) in aqueous (H2O or D2O) formic acid solutions were investigated by electrospray mass spectrometry (ESI MS), isothermal titration calorimetry (ITC) and NMR titration. DFT calculations were also performed to rationalize the experimental findings. ESI MS data indicate that the studied cucurbiturils bind TREN amine forming two types of adducts of a 1:1 stoichiometry. Dipositive adducts are formed by CB6 and CB7 homologues, while tripositive adducts are formed by CB7 and CB8 homologues. DFT calculations show that the type of the formed adduct is connected with the dimensions of the cucurbituril portal. The results of NMR and ITC measurements confirm that all three CBn homologues (n = 6–8) bind TREN ligands spontaneously in the liquid phase. According ITC results the CB7 homologue binds this amine more strongly than the CB6 and CB8 homologues.
Journal of Molecular Liquids
Abstract We performed calorimetric titration (ITC) measurements of aqueous albendazole solutions ... more Abstract We performed calorimetric titration (ITC) measurements of aqueous albendazole solutions with aqueous β-cyclodextrin solutions. The obtained results were used to determine the enthalpy and entropy of the drug–β-cyclodextrin interaction, the stoichiometry of the resulting inclusion complex and its formation constant. Using the UV spectrophotometer, we determined the solubility of albendazole in water, as well as the increase of the drug solubility driven by the increase of β-cyclodextrin concentration. Biological studies carried out on mouse cultures confirmed an increase of the albendazole–β-cyclodextrin complex bioavailability, as compared to the uncomplexed drug.
Journal of Molecular Liquids
Journal of Molecular Liquids
The Journal of Chemical Thermodynamics
Journal of Molecular Liquids