Binding studies of hydroxylated Multi-Walled Carbon Nanotubes to hemoglobin, gamma globulin and transferrin

The interaction of cinchonine and immunoglobulin G and the development of a nanocomplex with improved anti-breast cancer activity

In this study we evaluated the interaction of cinchonine (Cin) and immunoglobulin G (IgG). Then, Cin-IgG nanoparticles (NPs) were synthesized and characterized. Finally, the anticancer effects of free Cin and Cin-IgG NPs on MCF-7 breast cancer (BC) cells were evaluated. The results of spectroscopy measurements show that the IgG-Cin complex's quenching mechanism is static and the structure of IgG was partially changed following interaction with Cin. The prepared Cin-IgG NPs display a hydrodynamic size of 190 nm with a PDI of 0.269, a zeta potential of -38.05 mV, an EE% of 72.38 %, a LC% of 5.41 %, and a pH-sensitive drug release behavior. In the cellular assay, it was found that the calculated IC50 concentrations of Cin, IgG NPs, and Cin-IgG NPs are 66.4 ± 5.39, >100, and 29.2 ± ± 4.11 μM, respectively, in MCF-7 BC cells. Finally, Cin-IgG NPs induce a greater effect on the overexpression of the Bax/Bcl-2 ratio and downregulation of PI3K/p-AKT compared to the free drug. In conclusion, this study shows that Cin has the potential to bind IgG as a human plasma protein, and its complexation into a NP form with IgG can boost its anti-BC effects.

Detection of carbon nanotubes in bovine raw milk through Fourier transform Raman spectroscopy

The potential use of carbon-based methodologies for drug delivery and reproductive biology in cows raises concerns about residues in milk and food safety. This study aimed to assess the potential of Fourier transform Raman spectroscopy and discriminant analysis using partial least squares (PLS-DA) to detect functionalized multiwalled carbon nanotubes (MWCNT) in bovine raw milk. Oxidized MWCNT were diluted in milk at different concentrations from 25.00 to 0.01 µg/mL. Raman spectroscopy measurements and PLS-DA were performed to identify low concentrations of MWCNT in milk samples. The PLS-DA model was characterized by the analysis of the variable importance in projection (VIP) scores. All the training samples were correctly classified by the model, resulting in no false-positive or false-negative classifications. For test samples, only one false-negative result was observed, for 0.01 µg/mL MWCNT dilution. The association between Raman spectroscopy and PLS-DA was able to identify MWCNT diluted in milk samples up to 0.1 µg/mL. The PLS-DA model was built and validated using a set of test samples and spectrally interpreted based on the highest VIP scores. This allowed the identification of the vibrational modes associated with the D and G bands of MWCNT, as well as the milk bands, which were the most important variables in this analysis.

The attenuating ability of deep eutectic solvents towards the carboxylated multiwalled carbon nanotubes induced denatured β-lactoglobulin structure

The stabilization of proteins has been a major challenge for their practical utilization in industrial applications. Proteins can easily lose their native conformation in the presence of denaturants, which unfolds the protein structure. Since the introduction of deep eutectic solvents (DESs), there are numerous studies in which DESs act as promising co-solvents that are biocompatible with biomolecules. DESs have emerged as sustainable biocatalytic media and an alternative to conventional organic solvents and ionic liquids (ILs). However, the superiority of DESs over the deleterious influence of denaturants on proteins is often neglected. To address this, we present the counteracting ability of biocompatible DESs, namely, choline chloride-glycerol (DES-1) and choline chloride-urea (DES-2), against the structural changes induced in β-lactoglobulin (Blg) by carboxylated multiwalled carbon nanotubes (CA-MWCNTs). The work is substantiated with various spectroscopic and thermal studies. The spectroscopic results revealed that the fluorescence emission intensity enhances for the protein in DESs. Contrary to this, the emission intensity extremely quenches in the presence of CA-MWCNTs. However, in the mixture of DESs and CA-MWCNTs, there was a slight increase in the fluorescence intensity. Circular dichroism spectral studies reflect the reappearance of the native band that was lost in the presence of CA-MWCNTs, which is a good indicator of the counteraction ability of DESs. Further, thermal fluorescence studies showed that the protein exhibited extremely great thermal stability in both DESs as well as in the mixture of DES-CA-MWCNTs compared to the protein in buffer. This study is also supported by dynamic light scattering and zeta potential measurements; the results reveal that DESs were successfully able to maintain the protein structure. The addition of CA-MWCNTs results in complex formation with the protein, which is indicated by the increased hydrodynamic size of the protein. The presence of DESs in the mixture of CA-MWCNTs and DESs was quite successful in eliminating the negative impact of CA-MWCNTs on protein structural alteration. DES-1 proved to be superior to DES-2 over counteraction against CA-MWCNTs and maintained the native conformation of the protein. Overall, both DESs act as recoiling media for both native and unfolded (denatured by CA-MWCNTs) Blg structures. Both the DESs can be described as potential co-solvents for Blg with increased structural and thermal stability of the protein. To the best of our knowledge, this study for the first time has demonstrated the role of choline-based DESs in the mixture with CA-MWCNTs in the structural transition of Blg. The DESs in the mixture successfully enhance the stability of the protein by reducing the perturbation caused by CA-MWCNTs and then amplifying the advantages of the DESs present in the mixture. Overall, these results might find implications for understanding the role of DES-CA-MWCNT mixtures in protein folding/unfolding and pave a new direction for the development of eco-friendly protein-protective solvents.

The interaction mechanism of plasma iron transport protein transferrin with nanoparticles

In the biological systems, exposure to nanoparticles (NPs) can cause complicated interactions with proteins, the formation of protein corona and structural changes to proteins. These changes depend not only on NP physicochemical properties, but also on the intrinsic stability of protein molecules. Although, the formation of protein corona on the surface of NPs and the underlying mechanisms have been fully explored in various studies, no comprehensive review has discussed the direct biochemical and biophysical interactions between NPs and blood proteins, particularly transferrin. In this review, we first discussed the interaction of NPs with proteins to comprehend the effects of physicochemical properties of NPs on protein structure. We then overviewed the transferrin structure and its direct interaction with NPs to explore transferrin stability and its iron ion (Fe3+) release behavior. Afterwards, we surveyed the various biological functions of transferrin, such as Fe3+ binding, receptor binding, antibacterial activity, growth, differentiation, and coagulation, followed by the application of transferrin-modified NPs in the development of drug delivery systems for cancer therapy. We believe that this study can provide useful insight into the design and development of bioconjugates containing NP-transferrin for potential biomedical applications.

Understanding the close encounter of heme proteins with carboxylated multiwalled carbon nanotubes: a case study of contradictory stability trend for hemoglobin and myoglobin

Carbon nanotubes (CNTs) are one of the unique and promising nanomaterials that possess plenty of applications, such as biosensors, advanced drug delivery systems and biotechnology. CNTs bind rapidly with proteins, which result in the formation of a protein coating layer known as a "protein corona" around the surface of the nanomaterial. This hinders their applications as a drug carrier and influences the properties of biological macromolecules. The present work focuses on studying the thermal stability and molecular level interactions of two heme proteins, hemoglobin (Hb) and myoglobin (Mb), in the presence of carboxylated functionalized multi-walled CNTs (CA-MWCNTs). Through the current study, the following steps have been taken to distinguish the biocompatibility of the hydrophilic surface CA-MWCNTs for heme proteins via a series of spectroscopic techniques and differential scanning calorimetry (DSC). UV-Visible and steady-state fluorescence spectroscopy were used to reveal changes in the aromatic amino acid residues of heme proteins upon the addition of CA-MWCNTs. Circular dichroism spectroscopy (CD) shows the alteration in the native structure of proteins in the presence of the nanomaterial. A tremendous increase in the size of the protein CA-MWCNTs system is observed in dynamic light scattering (DLS), which clearly manifests the protein corona formation. Unexpectedly, both proteins interact differently with CA-MWCNTs, which is observed in CD spectroscopy and DSC. In the presence of CA-MWCNTs, an increase in the transition temperature (T_m) was observed for Hb, while the T_m value decreases for Mb. Different interactions with proteins at the molecular scale may be the reason for this unexpected behavior. Henceforth, the present results can help in the design of the next-generation drug carrier nanomaterials with the idea of the heme protein corona formation prior to development.

Investigating the interaction of CdTe quantum dots with plasma protein transferrin and their interacting consequences at the molecular and cellular level

This study investigated the interacting mechanism of CdTe quantum dots (QDs) with typical plasma protein transferrin (TF) as well as the impact of the formation of QDs-TF complex on the structure of TF and the cytotoxicity of mouse primary kidney cells. Dialysis experiments and cell viability assays revealed that the formation of QDs-TF complex reduced the contents of Cd released from CdTe QDs and thus counteracted the cytotoxicity of CdTe QDs. The assay of isothermal titration calorimetry found that CdTe QDs complexed with TF majorly through hydrophobic interaction. Multi-spectroscopic measurements showed that CdTe QDs caused the loosening of polypeptide chain, the changes of secondary and tertiary structures as well as the attenuated aggregation of TF molecule. Moreover, these structural and conformational changes were attributed to the nano-effects of CdTe QDs rather than the released Cd. This study is of great significance for fully evaluating the biocompatibility of Cd-QDs and comprehensively understanding the mechanism of Cd-QDs toxicity at the molecular and cellular level.

Selenium nanoparticles: Synthesis, in-vitro cytotoxicity, antioxidant activity and interaction studies with ct-DNA and HSA, HHb and Cyt c serum proteins

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Spherical SeNPs with average size 134 nm were synthesized employing Vitamin C.

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The synthesized SeNPs represented great antioxidant and anticancer activity.

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The interaction of SeNPs with ct-DNA, HSA, HHb and Cyt c was investigated.

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Nano-selenium can bind to ct-DNA through partial intercalation binding mode.

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HSA, HHb and Cyt c could keep their biological activity even in the presence of Nano-selenium.

The aim of this study was the synthesis of selenium nanoparticles (SeNPs) employing vitamin C as a biocompatible and low toxic reducing agent. The synthesized selenium nanoparticles were characterized by using UV–vis, FT-IR, SEM-EDX, TEM, DLS, and zeta potential measurements. The results of the DPPH free radical scavenging assay demonstrate that this synthesized nano-selenium has strong potentials to scavenge the free radicals and cytotoxicity against MCF-7 and Raji Burkitt's lymphoma cancer cell lines. The interaction of calf thymus DNA (ct-DNA) with SeNPs indicated that the anticancer activity might be associated with the DNA-binding properties of nano-selenium. Finally, it was found that the synthesized nano-selenium can bind to the most important blood proteins such as human serum albumin (HSA), human hemoglobin (HHb), and Cytochrome c (Cyt c). The results showed that the secondary structure of these proteins remains unchanged, suggesting that the synthesized nano-selenium could be employed as a carrier in the drug delivery system without any cytotoxicity effect.

Interaction of bisphenol A 3, 4-quinone metabolite with human hemoglobin, human serum albumin and cytochrome c in vitro

Since covalent protein-bisphenol A adducts generated by the interaction of protein nucleophiles with bisphenol A quinone affect the physicochemical properties of proteins in functional foods and biological tissues, it has become a hot topic nowadays. Therefore, we investigated the interaction of several different biomacromolecules such as hemoglobin, human serum albumin and cytochrome c with bisphenol A 3, 4-quinone (BPAQ). The effects of binding on changes in biomolecular structure were determined by various spectroscopic methods. BPAQ effects were investigated by using the UV-Vis spectroscopy and the quenching phenomenon from fluorescence emission. It proved that the formation of bio-complex and their aromatic micro-environment was likely to be disturbed with as well. Changes observed in circular dichroism (CD) spectroscopy confirmed the quantitative loss of the alpha-helical structure. Further studies with matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOFMS) and molecular docking indicated combining ratio and binding sites between proteins and BPAQ. The in vitro data of BPAQ-proteins adducts may provide a valuable theoretical basis for the elucidation of the toxicological mechanisms of BPAQ adducts in biological systems and environments.

Biophysical, bioinformatical, cellular, and molecular investigations on the effects of graphene oxide nanosheets on the hemoglobin structure and lymphocyte cell cytotoxicity

BACKGROUND

Implementations of nanoparticles have been receiving great interest in medicine and technology due to their unique characteristics. However, their toxic impacts on the biological system are not well explored.

AIM

This study aims to investigate the influence of fabricated nano graphene oxide (NGO) sheets on the secondary and quaternary structural alterations of human hemoglobin (Hb) and cytotoxicity against lymphocyte cells.

MATERIALS AND METHODS

Different spectroscopic methods, such as extrinsic and synchronous fluorescence spectroscopy and far circular dichroism (CD) spectroscopy, molecular docking investigation, cellular assays (trypan blue exclusion, cellular uptake, ROS, cell cycle, and apoptosis), and molecular assay (fold changes in anti/proapoptotic genes [B-cell lymphoma-2 {BCL2}/BAX] expression levels) were used in this study.

RESULTS

Transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and zeta potential investigations revealed the nano-sized nature of NGOs with good colloidal stability. Extrinsic fluorescence spectroscopy by using 8-anilinonaphthalene-1 -sulfonic acid and synchronous fluorescence spectroscopy showed that NGOs can unfold the quaternary structure of Hb in the vicinity of Tyr residues. The CD investigation demonstrated that the α-helicity of Hb experienced substantial alteration upon interaction with increasing concentrations of NGOs. The molecular docking study showed that NGOs interacted with polar residues of Hb. Cellular and molecular assays revealed that NGOs lead to ROS formation, cell cycle arrest, and apoptosis through the BAX and BCL2 pathway.

CONCLUSION

These data reveal that NGOs can induce some protein structural changes and stimulate cytotoxicity against normal cell targets. Therefore, their applications in healthy systems should be limited.

Biophysical, docking, and cellular studies on the effects of cerium oxide nanoparticles on blood components: in vitro

Introduction

The application of nanoparticles (NPs) in medicine and biology has received great interest due to their novel features. However, their adverse effects on the biological system are not well understood.

Materials and methods

This study aims to evaluate the effect of cerium oxide nanoparticles (CNPs) on conformational changes of human hemoglobin (HHb) and lymphocytes by different spectroscopic (intrinsic and synchronous fluorescence spectroscopy and far and near circular dichroism [CD] spectroscopy), docking and cellular (MTT and flow cytometry) investigations.

Results and discussion

Transmission electron microscopy (TEM) showed that CNP diameter is ~30 nm. The infrared spectrum demonstrated a strong band around 783 cm⁻¹ corresponding to the CNP stretching bond. Fluorescence data revealed that the CNP is able to quench the intrinsic fluorescence of HHb through both dynamic and static quenching mechanisms. The binding constant (K_b), number of binding sites (n), and thermodynamic parameters over three different temperatures indicated that hydrophobic interactions might play a considerable role in the interaction of CNPs with HHb. Synchronous fluorescence spectroscopy indicated that microenvironmental changes around Trp and Tyr residues remain almost unchanged. CD studies displayed that the regular secondary structure of HHb had no significant changes; however, the quaternary structure of protein is subjected to marginal structural changes. Docking studies showed the larger CNP cluster is more oriented toward experimental data, compared with smaller counterparts. Cellular assays revealed that CNP, at high concentrations (>50 µg/mL), initiated an antiproliferative response through apoptosis induction on lymphocytes.

Conclusion

The findings may exhibit that, although CNPs did not significantly perturb the native conformation of HHb, they can stimulate some cellular adverse effects at high concentrations that may limit the medicinal and biological application of CNPs. In other words, CNP application in biological systems should be done at low concentrations.

Para-tertiary butyl catechol induces eryptosis in vitro via oxidative stress and hemoglobin leakage in human erythrocytes

Exposure of human population to industrial chemicals is believed as a significant contributing factor to the outgrowth of occupational diseases especially in developing countries due to improper safety measures and sanitary conditions. Para-tertiary butylcatechol (PTBC) widely employed in petrochemical, thermofax and phototypesetting industries, induces melanocytotoxicity and contact dermatitis leading to occupational leukoderma/vitiligo. Few vitiligo patients were reported for oxidative stress-induced hemolytic anemia and thrombocytopenia, however its impact on blood components is still not clear. Erythrocytes are the major cell population in circulation and play a prominent role in various diseases. In this work, the effect of PTBC on human erythrocytes is evaluated in vitro. PTBC induces oxidative stress-mediated eryptosis (erythrocyte death) causing detrimental changes such as depleted antioxidant levels, altered surface morphology, hemoglobin denaturation and heinz body formation. These findings validate that PTBC could induce toxic effects on human erythrocytes. Exposure of humans to toxic chemicals constitutes an important issue in various industries; one such issue is the exposure of PTBC at work place resulting in a spectrum of dermal complications. Therefore, it is imperative to appraise the long-term toxicities in order to further delineate the mechanisms of resultant disorders associated with PTBC and to establish the therapeutic interventions.

Thermodynamic and conformational changes of protein toward interaction with nanoparticles: a spectroscopic overview

Nanoparticles (NPs) in different forms have been widely used in medicine and pharmaceutics for diagnosis and drug delivery.