An insight into the binding of an ester functionalized gemini surfactant to hemoglobin

Spectroscopic characterization of triazine based covalent organic framework tempted changes in the structure of hemoglobin

The present study aims to understand changes in the Hemoglobin (Hb) structure in the presence of a triazine based covalent organic framework (COF) through spectroscopic characterization. Covalent Organic Frameworks (COFs) due to their unique properties have been utilized in diverse fields including bio-applications. Utilization of COFs for conjugate formation with proteins will lead to the integration of biology and framework materials that can help in the development of bioconjugates for advanced bio-based applications such as diagnostics, therapeutics, and bioengineering. However, vital is to have a fundamental understanding of protein conformation in protein-COF conjugate. Herein, a triazine based COF has been synthesized via solvothermal method, termed TATF-COF which has been utilized for the formation of a conjugate with hemoglobin (Hb). Thereafter, studies have been performed to understand Hb structure in the presence of TATF-COF. Results from UV-vis, Fluorescence, and UV-CD spectroscopy studies revealed that in the presence of TATF-COF, there was a slight alteration in the Hb structure due to binding interactions between them and conjugate formation. Moreover, micrographs obtained from electron microscopy displayed formation of conjugate between Hb and TATF-COF result of binding interactions. DLS and zeta potential results also revealed conjugate formation due to binding interactions between TATF-COF and Hb. Thermal stability of Hb was also maintained as TATF-COF had insignificant effect on the Tm value of Hb. Overall, there was a slight alternation in the Hb native conformation due to binding interactions, however, TATF-COF was compatible with Hb as the protein's native structure was well-preserved.

Biocompatibility assessment of chemically modified GONRs with hemoglobin and histopathological studies for its toxicity evaluation

Transition metal-Schiff base complexes are found to be important for biomedical applications but have demerits of being homogeneous complexes, thus their synthesis on the surface of graphene oxide nanoribbons (GONRs), materials of specific interest, can be beneficial for preparing advanced graphene-based materials for biomedical applications. Of foremost importance is their safety and biocompatibility with biological systems. In this study, a transition metal-Schiff base complex has been synthesized on the surface of a GONR (Ni-S-GNR) using 3-aminopropyltriethoxysilane and pyridine-2-carbaldehyde and complexing nickel. This Ni-S-GNR was characterized well by various physicochemical techniques. The evaluation of biocompatibility of Ni-S-GNR with hemoglobin confirmed binding interactions and influence on the native structure of hemoglobin. It was found that there was alteration in the secondary and tertiary structures of hemoglobin. In addition, histopathological studies on the liver and kidney cells of rats revealed non-toxicity of Ni-S-GNR towards these cells. Overall, Ni-S-GNR was found to be compatible with protein as the native structure was not destroyed and was non-toxic to cells.

Molecular Interaction of Amino Acid-Based Gemini Surfactant with Human Serum Albumin: Tensiometric, Spectroscopic, and Molecular Docking Study

Binding effect and interaction of N,N'-dialkyl cystine based gemini surfactant (GS); 2(C₁₂Cys) with human serum albumin (HSA) were systematically investigated by the techniques such as surface tension measurement, UV-visible spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and molecular docking studies. The surface tension measurement exhibited that HSA shifted the critical micelle concentration of the 2(C₁₂Cys) GS to the higher side that confirms the complex formation among 2(C₁₂Cys) GS and HSA which was also verified by UV-visible, fluorescence, and CD spectroscopy. Increase in the concentration of 2(C₁₂Cys) GS increases the absorption of the HSA protein but has a reverse effect on the fluorescence intensity. The analysis of UV-visible study with the help of a static quenching method showed that the value acquired for the bimolecular quenching constant (k _q) quenches the intrinsic fluorescence of the HSA protein. Synchronous fluorescence spectrometry declared that the induced-binding conformational changes in HSA and CD results explained the variations in the secondary arrangement of the protein in presence of 2(C₁₂Cys) GS. The present study revealed that the interaction between 2(C₁₂Cys) GS and HSA is important for the preparation and properties of medicines. Molecular docking study provides insight into the specific binding site of 2(C₁₂Cys) GS into the sites of HSA.

Probing the Intercalation of Noscapine from Sodium Dodecyl Sulfate Micelles to Calf Thymus Deoxyribose Nucleic Acid: A Mechanistic Approach

Noscapine (NOS) is efficient in inhibiting cellular proliferation and induces apoptosis in nonsmall cell, lung, breast, lymphatic, and prostate cancers. The micelle-assisted drug delivery is a well-known phenomenon; however, the proper mechanism is still unclear. Therefore, in the present study, we have shown a mechanistic approach for the delivery of NOS from sodium dodecyl sulfate (SDS) micelles to calf thymus deoxyribose nucleic acid (ctDNA) base-pairs using various spectroscopic techniques. The absorption and emission spectroscopy results revealed that NOS interacts with the SDS micelle and resides in its hydrophobic core. Further, the intercalation of NOS from SDS micelles to ctDNA was also shown by these techniques. The anisotropy and quenching results further confirmed the relocation of NOS from SDS micelles to ctDNA. The CD analysis suggested that SDS micelles do not perturb the structure of ctDNA, which supported that SDS micelles can be used as a safe delivery vehicle for NOS. This work may be helpful for the invention of advanced micelle-based vehicles for the delivery of an anticancer drug to their specific target site.

Conformational and solution dynamics of hemoglobin (Hb) in presence of a cleavable gemini surfactant: Insights from spectroscopy, atomic force microscopy, molecular docking and density functional theory

Herein, we have explored the conformational alterations of hemoglobin (Hb) in presence of a cleavable gemini surfactant (C16-C4O2-C16). The concerned surfactant was found to induce significant structural perturbations in Hb. UV-vis spectroscopy, steady-state/time-resolved fluorescence, and other utilized techniques have authenticated the complexation of Hb with the gemini surfactant. CD has demonstrated the alterations in secondary structural elements (α-helicity, β-sheet, β-turn, and random coil) of Hb upon C16-C4O2-C16 addition. Atomic force microscopy (AFM) has revealed the existence of unique star-shaped gemini surfactant microstructures aligned to Hb in a necklace pattern. The ¹H NMR peak broadening and lower delta values hint at the binding of the concerned gemini surfactant to Hb. Molecular docking and DFT calculations have further substantiated the Hb-gemini complex formation and the involvement of electrostatic/hydrophobic forces therein. In future, these results might pave-the-way to construct self-assembled, sustainable, and green surfactant-protein mixtures for their end-use in industrial, engineering, biomedical, drug delivery, gene transfection, and other relevant excipient formulations.

Interaction of promethazine and adiphenine to human hemoglobin: A comparative spectroscopic and computational analysis

The binding nature of amphiphilic drugs viz. promethazine hydrochloride (PMT) and adiphenine hydrochloride (ADP), with human hemoglobin (Hb) was unraveled by fluorescence, absorbance, time resolved fluorescence, fluorescence resonance energy transfer (FRET) and circular dichroism (CD) spectral techniques in combination with molecular docking and molecular dynamic simulation methods. The steady state fluorescence spectra indicated that both PMT and ADP quenches the fluorescence of Hb through static quenching mechanism which was further confirmed by time resolved fluorescence spectra. The UV-Vis spectroscopy suggested ground state complex formation. The activation energy (E_a) was observed more in the case of Hb-ADP than Hb-PMT interaction system. The FRET result indicates the high probability of energy transfer from β Trp37 residue of Hb to the PMT (r=2.02nm) and ADP (r=2.33nm). The thermodynamic data reveal that binding of PMT with Hb are exothermic in nature involving hydrogen bonding and van der Waal interaction whereas in the case of ADP hydrophobic forces play the major role and binding process is endothermic in nature. The CD results show that both PMT and ADP, induced secondary structural changes of Hb and unfold the protein by losing a large helical content while the effect is more pronounced with ADP. Additionally, we also utilized computational approaches for deep insight into the binding of these drugs with Hb and the results are well matched with our experimental results.

The adsorption and aggregation properties of dendritic cationic tetrameric surfactants

A series of dendritic cationic tetrameric surfactants (4C_ntetraQ, n = 12, 14, 16) were synthesized with raw materials that are commercially available.

Unraveling the interaction of hemoglobin with a biocompatible and cleavable oxy-diester-functionalized gemini surfactant

Surfactant-protein mixtures have attracted considerable research interest in recent years at the interface of chemical biology and medicinal chemistry. Herein, the interaction between a green gemini surfactant (C₁₆-E2O-C₁₆) and a redox protein hemoglobin was examined through a series of in vitro experimental techniques with an attempt to provide a comprehensive knowledge of the surfactant-protein binding interactions. Quantitative appraisal of the fluorescence/CV data showed that the binding of C₁₆-E2O-C₁₆ to Hb leads to the formation of thermodynamically favorable non-covalent adduct with 1:1 stoichiometry. UV-vis spectra demonstrated that the effect of C₁₆-E2O-C₁₆ on Hb is highly concentration dependent. Far-UV and near-UV CD spectra together elucidated the formation of molten globule state of Hb upon C₁₆-E2O-C₁₆ addition. Temperature dependent CD explicated the effect of C₁₆-E2O-C₁₆ on the thermal stability of Hb. Furthermore, the structural investigation of Hb via pyrene/synchronous/three-dimensional fluorescence and FT-IR spectroscopy provided the complementary information related to its microenvironmental and conformational changes. Computational studies delineated that C₁₆-E2O-C₁₆ binds in the vicinity of β-37 Trp at the α₁β₂ interface of Hb. Overall, this study is expected to clarify the binding mechanism between Hb/other congeners and surfactant at the molecular level that are known to have immense potential in biomedical and industrial areas.

The characterization of 1-(4-bromophenyl)-5-phenyl-1H-1,2,3-triazole on acute toxicity, antimicrobial activities, photophysical property, and binding to two globular proteins

1-(4-Bromophenyl)-5-phenyl-1H-1,2,3-triazole (BPT) was a newly synthesized compound. The acute toxicities of BPT to mice by intragastric administration have been determined and the result indicates that the intragastric administration of BPT did not produce any significant toxic effect on Kunming strain mice. It is also evaluated for the antimicrobial activity of BPT against three kinds of plant mycoplasma, Fusarium Wilt (race 4), Colletotrichum gloeosporioides Penz. and Xanthomonas oryzae by different method in vitro. The compound exhibited distinct inhibitory activities against Fusarium Wilt (race 4) and Colletotrichum gloeosporioides Penz. by mycelium growth rate test and the values of EC₅₀ were 29.34 and 12.53μg/mL respectively. And BPT had also the most potent inhibitory activities against Xanthomonas oryzae when compared with that of control drugs by the agar well diffusion method. In addition, the structural and photophysical properties of BPT including ionization energy, electron affinities, and theoretical spectrum was studied by quantum-chemical methods. Then the interaction of BPT with two kinds of globular proteins, human immunoglobulin (HIg) and bovine hemoglobin (BHg) was investigated by using UV-vis absorption spectra, synchronous fluorescence, 3D fluorescence spectra, and fluorescence titration in combination with molecular modeling. UV-vis absorption, 3D and synchronous fluorescence measurements show that BPT has influence on the microenvironment surrounding HIg or BHg in aqueous solution and the fluorescence experiments show that BPT quenches the fluorescence intensity of HIg or BHg through a static mechanism. The binding parameters including the binding constants, the number of binding site and average binding distance between BPT and HIg or BHg at different temperatures were calculated. The thermodynamic parameters suggest that the hydrophobic interaction is the predominant intermolecular forces in stabilizing the BPT-HIg or BPT-BHg complex. Molecular docking was performed to reveal that the BPT moiety binds to the hydrophobic cavity of HIg or BHg and they are in good agreement with the spectroscopic measurements.