Binding Constants Research Articles

A bisalicylhydrazone based fluorescent probe for detecting Al3+ with high sensitivity and selectivity and imaging in living cells

A bisalicylhydrazone based fluorescence probe, bisalicyladehyde benzoylhydrazone (BS-BH), has been designed to detect Al3+. It exhibited high sensitivity and selectivity towards Al3+ in methanol–water media in physiological condition. Large stokes shifts (∼122 nm) and over ∼1000-fold enhanced fluorescence intensity were observed, which was ascribed to the formation of the two relatively independent rigid extended π conjugated systems bridged by biphenyl group when binding with Al3+. A 1:2 binding ratio between BS-BH and Al3+ was shown by Job’s plot. Based on the fluorescence titration data, the detection limit was down to 3.50 nM and the association constant was evaluated to be 1.12 × 109 M−2. The plausible fluorescence sensing mechanism of suppressed ESIPT, inhibited PET, activated CHEF and restricted C = N isomerization was confirmed by a variety of spectral experiments and DFT / TD-DFT calculations. The reversibility of recognition of Al3+ for probe BS-BH was validated by adding Na2-EDTA. In addition, the MTT assay showed the good biocompatibility of BS-BH and BS-BH could be used for imaging Al3+ in living cells.

In-Vitro Study of the Binding of Atorvastatin with Adenine using Multi-Spectroscopic Approaches.

Atorvastatin-an oral lipid regulating drug is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), which is the rate determining enzyme for cholesterol synthesis. Adenine is a purine nucleobase that is found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to generate genetic information. The binding mechanism of atorvastatin and adenine was studied for the first time utilizing various techniques, including UV-visible spectrophotometry, spectrofluorimetry, synchronous fluorescence spectroscopy (SF), Fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET), and metal ion complexation. The fluorescence spectra of the complex indicated that atorvastatin is bound to adenine via hydrophobic interaction through a spontaneous binding process, and the fluorescence quenching mechanism was found to be static quenching with a binding constant of 1.4893 × 104 Lmol-1 at 298 K. Various temperature settings were used to investigate thermodynamic characteristics, such as binding forces, binding constants, and the number of binding sites. The interaction parameters, including the standard enthalpy change (ΔHο) and standard entropy change (ΔSο) were calculated using Van't Hoff's equation to be 42.82 kJmol-1 and 208.9 Jmol-1K-1, respectively. The findings demonstrated that the adenine- atorvastatin binding was endothermic. Furthermore, the results of the experiments revealed that some metal ions (K+, Ca+2, Co+2, Cu+2, and Al+3) facilitate the binding interaction between atorvastatin and adenine. Slight changes are observed in the FTIR spectra of adenine, indicating the binding interaction between adenine and atorvastatin.

Tyrosinase inhibition, molecular docking and molecular dynamics simulation studies of anthraquinone derivative from aloe vera as potential pigmentation dermatosis and anti-food browning agent

The prevention of enzymatic browning through the application of tyrosinase inhibitors has become a research focus in food industry. In this article, multi-spectroscopic and computational simulation was used to study the binding behavior and inhibition mechanism of aloin to tyrosinase. It found that aloin was an effective inhibitor of tyrosinase activity with a mixed type inhibition. Aloin bound to tyrosinase through hydrophobic forces, causing a conformational change in the enzyme and resulting in its inherent fluorescence being quenched. There was a binding site for aloin with tyrosinase and the binding constant was approximately 104 L mol−1. Molecular simulations showed that hydrophobic and hydrogen-bonding forces were the main factors in the binding of aloin to tyrosinase. Aloin introduced into the active site of tyrosinase interacted with amino acid residues Gly281, His244, Val283, Ala286 and His263, occupying the catalytic center of the tyrosinase and blocking substrate entry, resulting in tyrosinase inhibition. Molecular dynamics simulation further indicated that the binding of aloin changed the secondary structure of tyrosinase with little effect on the microenvironment of tyrosinase amino acid residues. This study offers new understanding of the mechanisms of activity of aloin as a tyrosinase inhibitor.

Eco-friendly Fluorescent Sensor for Sensitive and Selective Detection of Zn2+ and Fe3+ Ions: Applications in Human Hair Samples.

A new eco-friendly sensor, 3-((6-((4-chlorobenzylidene)amino)pyridin-2-yl)imino)indolin-2-one (CBAPI) was synthesized and well characterized. The CBAPI sensor was employed for detecting Zn2+ and Fe3+ ions. It exhibited a low limit of detection at pH 6.0, with values of 2.90, for Zn2+ and 3.59nmol L-1 for Fe3+ ions. The sensor demonstrated high selectivity over other interfering cations. Additionally, the high binding constants reflect the great affinity of sensor towards Zn2+ and Fe3+ ions. To further validate its quantification ability for Zn2+ ions, the synthesized CBAPI sensor was used to determine Zn levels in human hair samples, and the results were confirmed using atomic absorption spectroscopy (AAS). The AGREE metric tool was used to assess the method's environmental impact and practical applicability. These positive outcomes indicated that the new method for detecting Zn2+ and Fe3+ ions is environmentally friendly and safe for humans. The developed CBAPI sensor represents a potential development in metal ion detection, combining sensitivity, selectivity, and rapidity.

Site‐Selective MoS2‐Based Sensor for Detection and Discrimination of Triethylamine from Volatile Amines Using Kinetic Analysis and Machine Learning

AbstractDetection and discrimination of volatile organic compounds (VOCs) is important to provide a more realistic assessment of their potential implication in complex environments and medical diagnostics based on volatile biomarkers. Herein, chemiresistive sensors are fabricated using stacked MoS2 nanoflakes with defects and exposed‐edge sites. The sensor is found to be extremely selective to triethylamine (TEA) over polar, non‐polar VOCs and atmospheric gases. The sensor exhibits a sensitivity of 1.72% ppm−1, fast response/recovery (19 s/39 s) to 100 ppm TEA at room temperature, low limit of detection (64 ppb), device reproducibility, humidity tolerance (RH 90%) and stability tested up to 60 days. The kinetic analysis of sensing curves reveals two discrete adsorption sites corresponding to edge and basal sites of interaction, with a higher rate constant of association and dissociation for TEA. The Density Functional Theory (DFT) studies support higher adsorption energy of TEA on MoS2 surface with respect to other volatile amines. The sensor demonstrates TEA recognition and composition estimation capability in a binary mixture of a similar class of VOCs using Machine Learning driven analysis with 95% accuracy. The ability to discriminate amines in binary mixture of other volatile amines paves the way for the advancement of next‐generation devices in the field of disease diagnosis.

Microwave assisted facile one pot synthesis of novel pyrazole derivative for multi-analyte detection (Fe3+ and Zn2+) and its solvatochromic studies

A novel heterocyclic pyrazole-based probe Ph-DB was synthesised by microwave assisted concatenation of phenyl hydrazine and 2,5-dibromo-3-thiophenecarboxylaldehyde. The veracity of synthesized pyrazole derivative was established using 1H NMR,13C NMR, HRMS and FT-IR. ICT studies were conducted in different organic solvents of varying polarity to comprehend the solvatochromic nature of compound. DFT studies were performed to elucidate the intricacies of the Ph-DB’s electronic structure. The electrochemical band gap and optical band gap were calculated using cyclic voltammetry and Tauc's plot respectively. SEM analysis was carried out to explore the surface morphology of Ph-DB which was found to show small microwires like structures which supports optoelectrical properties of Ph-DB. The photophysical studies were carried out to check the chromogenic and fluorogenic response of Ph-DB towards different metal ions. It was observed that Ph-DB shows noticeable fluorescence enhancement with Zn2+ ions with the detection limit of 6.1 µM and chromogenic change with Fe3+ with a detection limit of 6.6 µM. Additionally quantum yield, binding constant and recovery experiment of Ph-DB probe were performed. Ph-DB probe was utilised for precise monitoring of Zn2+ and Fe3+ ions in water samples.

Unraveling the interaction mechanism between orphan drug Nitisinone and bovine serum albumin through spectroscopic and in silico approaches

The interaction between Nitisinone (NTBC) and bovine serum albumin (BSA) as the transport protein in a circulating system was investigated for the first time utilizing various analytical (UV–Vis spectrophotometry, fluorescence spectroscopy, dynamic light scattering, and differential scanning calorimetry) and computational (molecular docking and molecular dynamics simulations) methods. The BSA fluorescence intensity was quenched upon interaction with NTBC, and the quenching mechanism was observed as static. The interaction between NTBC and BSA was examined at 288 K, 298 K, and 308 K where the binding constants were found to be 1.44 × 105 ± 0.22 M−1, 5.18 × 104 ± 0.20 M−1, and 3.02 × 104 ± 0.22 M−1 respectively, suggesting an intermediate binding affinity between NTBC and BSA. Changes in the microenvironment surrounding tryptophan and tyrosine residues of BSA were elucidated using 3-D fluorescence spectroscopy. Thermodynamic studies revealed the calculated values of ΔH = − 54.34 ± 5 kJ/mol and ΔS = − 0.0908 ± 0.24 kJ/mol K−1, indicating the involvement of van der Waals forces and hydrogen bonds in the interaction between NTBC and BSA. Moreover, the interaction’s spontaneous nature was evidenced by negative ΔG values across all temperatures. Using dynamic light scattering, it was observed that higher NTBC concentrations led to a gradual rise in hydrodynamic diameter and notable aggregation of the NTBC-BSA complex. Moreover, changing signal values and shifted peaks of BSA, NTBC, and complex in differential scanning calorimetry curves, meant there were molecular interactions between the NTBC and BSA. In silico approaches also elucidated how NTBC binds to active sites on BSA, further supporting other findings. Moreover, molecular docking studies offer a more profound insight into the changing dynamics of hydrophobic, hydrogen, and halogen bonding involved in stabilizing the NTBC-BSA complex.

Synthesis, optical properties, DNA, β-cyclodextrin interactions, and antioxidant evaluation of novel isoxazolidine derivative (ISoXD2): A multispectral and computational analysis

ISoXD2 are well explored among versatile and outstanding class of pharmacophores for the preparation and discovery of drugs. Herein, the electronic absorption and emission spectra of ISoXD2 were investigated in three different solvents. The observed transition was attributed to π-π* with charge transfer character. Changes in the excited state and shift of the absorption and emission peaks to longer wavelengths are observed as a result of increasing solvent polarity, due to the interactions between the ISoXD2 molecule and the solvent molecules surrounding it. Changing the solvent confirms its solvatochromic effect. UV–vis and fluorescence analysis revealed that ISoXD2 binds to deoxyribonucleic acid (DNA) by intercalation mode, with a stoichiometric ratio of 1:1.5. Moreover, the fluorescence intensity of DNA bound to ethidium bromide (EB) in the presence of ISoXD2 was investigated. From this analysis, the Stern-Volmer quenching constant (Ksv), quenching rate constant (kq), binding constant (Kb) and binding sites number (n) were found to be 5.654 × 103 M−1, 2.827 × 1011 M−1 s−1, 3.81 × 104 M−1 and 1.225, respectively. The interaction between ISoXD2 and β-CD was investigated through absorption spectra analysis. Kb for this interaction was determined to be 4.9 × 104 M−1. The free radical-scavenging ability of the prepared ISoXD2, examined by DPPH and ABTS assays have shown a good antioxidant activity. Furthermore, modeling study was conducted to explore their plausible binding mechanism with ISoXD2 and to support the experimental results.

Spectroscopic, electrochemical, and molecular docking studies of the interaction between the antihistamine drug desloratadine and dsDNA

Through the utilization of fluorescence spectroscopy, electrochemical, and molecular docking methods, this research investigates the interaction between the antihistamine drug desloratadine and calf thymus double-stranded DNA (ct-dsDNA). Deoxyguanosine (dGuo) and deoxyadenosine (dAdo) oxidation signals were diminished by incubation with varying concentrations of desloratadine, as determined by differential pulse voltammetry (DPV). This change was ascribed to desloratadine's binding mechanism to ct-dsDNA. The binding constant (Kb) between desloratadine and ct-dsDNA was determined to be 2.2 × 105 M−1 throughout electrochemical experiments. In order to further develop our comprehension of the interaction mechanism between desloratadine and ct-dsDNA, a series of spectroscopic experiments and molecular docking simulations were conducted. The Kb value was found to be 8.85 × 104 M−1 at a temperature of 25 °C by the use of fluorescence spectroscopic techniques. In summary, the utilization of electrochemical and spectroscopic techniques, alongside molecular docking investigations, has led to the prediction that desloratadine has the capability to interact with ct-dsDNA by groove binding.

Synthesis and logic gate application of quinoline schiff base probe for fluorescence detection of mercury ions

Herein, we report the synthesis of a small molecule quinoline Schiff-base “turn-on” fluorescence probe L, denoted as (2-NC9H6)C(H)=N(C6H4OCH3-p), utilizing 4-aminoanisole and quinoline-2-carboxaldehyde as precursors. The synthesized probe was comprehensively characterized through EA,1H/13C NMR, FT-IR, and ESI-MS spectral analysis. In a CH3CN/H2O solution (1/1, v/v, 0.01 M PBS buffer, pH = 7.30), probe L responded to Hg(II) with high sensitivity (LOD = 2.98 × 10−7 M) and selectivity. Upon binding to Hg(II), the fluorescence of the probe shifted from being initially off to a distinct blue emission. The probe L to Hg(II) binding ratio was 1:1 and the binding constant was 1.955 × 104 M−1. The detection mechanism of Hg(II) by probe L is due to the complex formation between the metal ion and imine nitrogen (–CH = N), thus causing chelation-enhanced fluorescence. TD-DFT studies at the B3LYP/6-31G(d) level of theory further confirmed that the complexation of L and Hg(II) occurred. Finally, probe L could reversibly identify Hg(II) upon adding EDTA, thus developing a molecular logic gate. In addition, this probe was successfully used to detect Hg(II) in actual water samples.

DNA binding/cleavage study of mixed ligand complexes of di-/triorganotin 4-fluoroanthranilates with 1,10-phenanthroline/benzimidazole: Synthesis, characterization, X-ray structures of [Bu2Sn(FA)2.phen], [Me3Sn(FA).bz], and DFT calculations

The mixed ligand complexes of di-/tri-organotin 4-fluoroanthranilates with 1,10-phenanthroline (phen), viz. [R2Sn(FA)2.phen] {R=Bu (1), Oct (2), Me (3)} and benzimidazole (bz), viz. [R3Sn(FA).bz] {R=Me (4), Ph (5)} have been synthesized and satisfactorily characterized by analytical and spectroscopic techniques, especially FT-IR, NMR (1H, 13C, and 119Sn NMR) spectroscopy and ESI-MS spectrometry. Single crystal-Xray diffraction measurements (Sc-XRD) confirmed a distorted pentagonal-bipyramidal geometry for complex (1), where one carboxylate group is monodentate, and the second (–COO) group behaves as a bidentate, while complex (4) affirms trigonal–bipyramidal geometry around the tin centre. The bond angles, especially ∠C–Sn–C obtained by optimizing complexes’ gaseous phase geometry showed significant conformity with the data obtained from Sc-XRD and NMR. The Kb (binding constant) and Ksv (Stern-Volmer quenching constant) values, ranging from 103 to 107, have been obtained through UV–visible absorption and fluorescence titrations with CT-DNA. These results strongly indicate partial minor groove binding/electrostatic interactions between the complex and CT-DNA, which has also been evidenced by circular dichroism studies. The studied complexes cleaved efficiently pBR322 plasmid DNA in NC (nicked circular form), SC (supercoiled form), and linear form.

دراسة توصيلية وحسابية للكلورامفينيكول في مذيبات ودرجات حرارية مختلفة

في العمل الحالي ، تم قياس الموصلية الكهربائية للكلورامفينيكول في الماء والميثانول عند درجات حرارة مختلفة 293-313 كلفن . تم تسجيل كل من المواصلة المكافئة عند درجة التخفيف اللانهائي (Λ0) وثابت التجمع الايوني (KA) والمسافة بين الايونات (R) باستخدام معادلة لي ويتون وتم حساب المعلمات الديناميكية الحرارية (متغير المحتوى الحراري، طاقة جيبس الحرة، متغير العشوائية) وبالمثل ، هناك معلومات نظرية وفيرة حول سلوك المركب مع المذيبات المختلفة (الماء والميثانول) من خلال حساب طاقات أعلى مدار جزيئي مشغول وادنى مدار جزيئي مشغول من المركب 2،2-ثنائي كلورو – N- (1R,2S)]- 1،3- ثنائي هيدروكسي-1- (4- نيتروفينيل) بروبان-2- يل] أسيتاميد عن طريق الحسابات الكومبيوترية (AM1, PM3, HF) وكانت إمكانات المركب مختلفة عند تغيير المذيب نتيجة لتباين قيمة الطاقة والعوامل النظرية الأخرى مثل الحجم الجزيئي ، معلمات كونولي.

Poly-Eriochrome Black T Decorated with Nickel Hydroxide Nanoparticles Modified Electrode for the Electrochemical Detection of Streptomycin and Probing its Interaction with Double-stranded DNA

We present a simple platform of poly-eriochrome Black T decorated with nickel hydroxide nanoparticles (Ni(OH)2NPs/PEBT) for the electrocatalytic oxidation of streptomycin (STRP) and probing its interaction with double-stranded DNA (ds-DNA). The electropolymerized eriochrome Black T modified glassy carbon electrode (GCE) was used to stabilize and synthesize Ni(OH)2NPs. The oxidation of STRP on Ni(OH)2NPs/PEBT/GCE mainly proceeded as a surface mechanism with the contribution of a diffusion-controlled process. A significant catalytic oxidation current of STRP was measured from an alkaline medium. It showed a dependence on the STRP concentrations in the range of 0.1 to 1.0 mM with a detection limit of 0.04 mM. The sensor has shown good recovery (85.3% to 90.2%, with RSD range of 1.27 to 8.83%) for the detection of STRP in diluted human serum. The interaction of STRP with ds-DNA was investigated from phosphate buffer pH 7.4 (0.2 M) using different electrode modifications (PEBT/GCE, and Ni(OH)2NPs/PEBT) in addition to bare GCE using voltammetric and impedance techniques. The binding constant of the STRP-DNA complex was calculated. Under the studied conditions, the interaction of ds-DNA with STRP in solution or on the surface of PEBT/GCE demonstrates their binding in intercalative and electrostatic modes.

Mechanism understanding of PIKfyve inhibitor YM201636 with human serum albumin: Insights from molecular modeling and multiple spectroscopic techniques.

YM201636 is the potent PIKfyve inhibitor that is being actively investigated for liver cancer efficacy. In this study, computer simulations and experiments were conducted to investigate the interaction mechanism between YM201636 and the transport protein HSA. Results indicated that YM201636 is stably bound between the subdomains IIA and IIIA of HSA, supported by site marker displacement experiments. YM201636 quenched the endogenous fluorescence of HSA by static quenching since a decrease in quenching constants was observed from 7.74 to 2.39 × 104 M-1. UV-vis and time-resolved fluorescence spectroscopy confirmed the YM201636-HSA complex formation and this binding followed a static mechanism. Thermodynamic parameters ΔG, ΔH, and ΔS obtained negative values suggesting the binding was a spontaneous process driven by Van der Waals interactions and hydrogen binding. Binding constants ranged between 5.71 and 0.33 × 104 M-1, which demonstrated a moderately strong affinity of YM201636 to HSA. CD, synchronous, and 3D fluorescence spectroscopy revealed that YM201636 showed a slight change in secondary structure. The increase of Kapp and a decrease of PSH with YM201636 addition showed that YM201636 changed the surface hydrophobicity of HSA. The research provides reasonable models helping us further understand the transportation and distribution of YM201636 when it absorbs into the blood circulatory system.

Spectroscopic Analysis of the Effect of Ibuprofen Degradation Products on the Interaction between Ibuprofen and Human Serum Albumin.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are one of the most commonly used groups of medicinal compounds in the world. The wide access to NSAIDs and the various ways of storing them due to their easy accessibility often entail the problem with the stability and durability resulting from the exposure of drugs to external factors. The aim of the research was to evaluate in vitro the mechanism of competition between ibuprofen (IBU) and its degradation products, i.e., 4'-isobutylacetophenone (IBAP) and (2RS)-2-(4- formylphenyl)propionic acid (FPPA) during transport in a complex with fatted (HSA) and defatted (dHSA) human serum albumin. The research was carried out using spectroscopic techniques, such as spectrophotometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The comprehensive application of spectroscopic techniques allowed, among others, for the determination of the binding constant, the number of classes of binding sites and the cooperativeness constant of the analyzed systems IBU-(d)HSA, IBU-(d)HSA-FPPA, IBU-(d)HSA-IBAP; the determination of the effect of ibuprofen and its degradation products on the secondary structure of albumin; identification and assessment of interactions between ligand and albumin; assessment of the impact of the presence of fatty acids in the structure of albumin and the measurement temperature on the binding of IBU, IBAP and FPPA to (d)HSA. The conducted research allowed us to conclude that the presence of ibuprofen degradation products and the increase in their concentration significantly affect the formation of the IBU-albumin complex and thus, the value of the association constant of the drug, changing the concentration of its free fraction in the blood plasma. It was also found that the presence of an ibuprofen degradation product in a complex with albumin affects its secondary structure.

Stereoisomers Are Not Machine Learning's Best Friends.

This study addresses the challenge of accurately identifying stereoisomers in cheminformatics, which originates from our objective to apply machine learning to predict the association constant between cyclodextrin and a guest. Identifying stereoisomers is indeed crucial for machine learning applications. Current tools offer various molecular descriptors, including their textual representation as Isomeric SMILES that can distinguish stereoisomers. However, such representation is text-based and does not have a fixed size, so a conversion is needed to make it usable to machine learning approaches. Word embedding techniques can be used to solve this problem. Mol2vec, a word embedding approach for molecules, offers such a conversion. Unfortunately, it cannot distinguish between stereoisomers due to its inability to capture the spatial configuration of molecular structures. This study proposes several approaches that use word embedding techniques to handle molecular discrimination using stereochemical information on molecules or considering Isomeric SMILES notation as a text in Natural Language Processing. Our aim is to generate a distinct vector for each unique molecule, correctly identifying stereoisomer information in cheminformatics. The proposed approaches are then compared to our original machine learning task: predicting the association constant between cyclodextrin and a guest molecule.

Synthesis, characterisation, and in vitro antiparasitic activity of new flavanoidal tetrazinan-6′-ones and their binding study with calf thymus DNA using molecular modelling and spectroscopic techniques

With the developing resistance to traditional antiparasitic medications, the purpose of this study was to efficiently develop a series of six noble flavanoidal tetrazinane-6′-one derivatives by a one-pot reaction pathway. FT-IR, 1HNMR, 13CNMR, and Mass spectra were employed for the structural elucidation of the synthesized compounds (7–12). Clinostomum complanatum, a parasite infection model that has been well-established, demonstrated that all the synthesized compounds are potent antiparasitic agents. DNA is the main target for various medicinal compounds. As a result, thestudy of how small molecules attach to DNA has received a lot of attention. In the present study, we have performed various biophysical techniques to determine the mode of binding of synthesized compounds (7–12) with calf thymus DNA (ct-DNA). It was observed from the UV–visible absorbance and fluorescence spectra that all synthesized compounds (7–12) form complexes with the ct-DNA. The value of binding constant (Kb) was obtained to be in the range of 4.36–––24.50 × 103 M - 1 at 298 K. Competitive displacement assay with ethidium bromide (EB), CD spectral analysis, viscosity measurements, and in silico molecular docking confirmed that ligands (7–12) incorporate with ct-DNA through groove binding only. Molecular docking studies were performed for all synthesized compounds with the calf thymus DNA and it was found that all the newly synthesized compounds strongly bind with the chain B of DNA in the minor groove with the value of binding energy in the range of −8.54 to −9.04 kcal per mole and several hydrogen bonding interactions.

SYNTHESIS, SPECTRAL STUDIES AND EVALUATION OF DNA BINDING, PHOTOCLEAVAGE, ANTICANCER ACTIVITY OF RU(II) POLYPYRIDYL COMPLEXES OF 2-(3,4,5-TRIMETHOXY-PHENYL)-H-IMIDAZOLE[4,5-F][1,10]PHENANTHROLINE

The two novel Ru(II) polypyridyl complexes of the type [Ru(NN)2L](ClO4)2.2H2O,where NN is dmp=4,4-dimethyl-1,10 ortho phenanthroline and dmb=4,4-dimethyl 2,2-bipyridine and L is Intercalator ligand, TMIP=2-(3,4,5-Trimethoxy-phenyl)-H-imidazole[4,5-f][1,10]phenanthroline were synthesized and characterized by different spectroscopic techniques. The binding ability of Ru (II) complexes with CT-DNA was investigated by Biophysical studies – UV-Visible absorption studies, Fluorescence studies (Emission & Quenching) and Viscosity studies. The binding constants of these complexes from absorption studies are 1.2x105 M-1and 8x104M-1respectively.These values are less as compared to the existing TMIP complex [Ru(phen)2TMPIP]+2, indicative of the effect of substitution over the ancillary ligand which reduce the binding capacity of metal complex to CT-DNA. The results from the viscosity studies suggest an intercalative binding mechanism. The DNA cleavage studies show that the Ru (II) complexes successfully cleaved the pBR322 DNA. Both the complexes exhibit not notable anti cancer acivity.

Dendrimer Platforms for Targeted Doxorubicin Delivery-Physicochemical Properties in Context of Biological Responses.

The unique structure of G4.0 PAMAM dendrimers allows a drug to be enclosed in internal spaces or immobilized on the surface. In the conducted research, the conditions for the formation of the active G4.0 PAMAM complex with doxorubicin hydrochloride (DOX) were optimized. The physicochemical properties of the system were monitored using dynamic light scattering (DLS), circular dichroism (CD), and fluorescence spectroscopy. The Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) method was chosen to determine the preferential conditions for the complex formation. The highest binding efficiency of the drug to the cationic dendrimer was observed under basic conditions when the DOX molecule was deprotonated. The decrease in the zeta potential of the complex confirms that DOX immobilizes through electrostatic interaction with the carrier's surface amine groups. The binding constants were determined from the fluorescence quenching of the DOX molecule in the presence of G4.0 PAMAM. The two-fold way of binding doxorubicin in the structure of dendrimers was visible in the Isothermal calorimetry (ITC) isotherm. Fluorescence spectra and release curves identified the reversible binding of DOX to the nanocarrier. Among the selected cancer cells, the most promising anticancer activity of the G4.0-DOX complex was observed in A375 malignant melanoma cells. Moreover, the preferred intracellular location of the complexes concerning the free drug was found, which is essential from a therapeutic point of view.

Binding constants and in silico analysis of albumin interaction with phenolic acids and flavonoids

Binding constants and in silico analysis of albumin interaction with phenolic acids and flavonoids