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Herein, the interaction of hen egg white lysozyme (HEWL) with iron nanoparticle (Fe NP) was investigated by spectroscopic and docking studies. The zeta potential analysis revealed that addition of Fe NP (6.45±1.03 mV) to HEWL (8.57±0.54 mV) can cause to greater charge distribution of nanoparticle-protein system (17.33±1.84 mV). In addition, dynamic light scattering (DLS) study revealed that addition of Fe NP (92.95±6.11 nm) to HEWL (2.68±0.37 nm) increases suspension potential of protein/nanoparticle system (51.17±3.19 nm). Fluorescence quenching studies reveled that both static and dynamic quenching mechanism occur and hydrogen bond and van der Waals interaction give rise to protein-NP system. Synchronous fluorescence spectroscopy of HEWL in the presence of Fe NP showed that the emission maximum wavelength of tryptophan (Trp) residues undergoes a red-shift. ANS fluorescence data indicated a dramatic exposure of hydrophobic residues to the solvent. The considerable reduction in melting temperature (T(m)) of HEWL after addition of Fe NP determines an unfavorable interaction system. Furthermore circular dichoroism (CD) experiments demonstrated that, the secondary structure of HEWL has not changed with increasing Fe NP concentrations; however, some conformational changes occur in tertiary structure of HEWL. Moreover, protein–ligand docking study confirmed that the Fe NP forms hydrogen bond contacts with HEWL.

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In this study, a novel method to probe molecular interactions and binding of human hemoglobin (Hb) with nanodiamond (ND) was introduced based on the surface tension measurement. This method complements conventional techniques, which are basically done by zeta potential and dynamic light scattering (DLS) measurements, near and far circular dichroism (CD) spectroscopy, intrinsic and extrinsic fluorescence spectroscopy. Addition of ND to Hb solution increased the surface tension value of Hb-ND complex relative to those of Hb and ND molecules. The zeta potential values reveled that Hb and ND provide identical charge distribution at pH 7.5. DLS measurements demonstrated that Hb, ND, and ND-Hb complex have hydrodynamic radiuses of 98.37 ± 4.57, 122.07 ± 7.88 nm and 62.27 ± 3.70 at pH of 7.5 respectively. Far and near UV-CD results indicated the loss of α-helix structure and conformational changes of Hb, respectively. Intrinsic fluorescence data demonstrated that the fluorescence quenching of Hb by ND was the result of the static quenching. The hydrophobic interaction plays a pivotal role in the interaction of ND with Hb. Fluorescence intensity changes over time revealed conformational change of Hb continues after the mixing of the components (Hb-ND) till 15 min, which is indicative of the denaturation of the Hb relative to the protein control. Extrinsic fluorescence data showed a considerable enhancement of the ANS fluorescence intensity of Hb-ND system relative to the Hb till 60 nM of ND, likely persuaded by greater exposure of nonpolar residues of Hb hydrophobic pocket. The remarkable decrease in T value of Hb in Hb-ND complex exhibits interaction of Hb with ND conducts to conformational changes of Hb. This study offers consequential discrimination into the interaction of ND with proteins, which may be of significance for further appeal of these nanoparticles in biotechnology prosecution.

<b><i>Introduction:</i></b> Peroxisome proliferator-activated receptors (PPARs), PPARα, PPARγ, and PPARδ, are nuclear ligand-activated transcription factors which presumably contribute to a broad range of pathophysiological processes, such as tumorigenesis. Nevertheless, their exact role as tumor suppressors or promoters is not straightforward in colorectal cancer (CRC). Therefore, expression values of these PPARs and their relation with tumor progression and prognosis were examined in CRC patients. <b><i>Methods:</i></b> In this work, the relative expression values of the PPARs were measured by real-time polymerase chain reaction in 100 CRC tumor tissues paired with adjacent normal tissues. After that, the association between relative expression values of the PPARs in tumor tissues and the cancer progression-related clinicopathological characteristics as well as overall survival of patients were assessed. <b><i>Results:</i></b> While PPARα and PPARδ seemed to be overexpressed, PPARγ was suppressed in CRC tumor tissues compared with paired adjacent normal tissues (<i>p</i> = 0.0001). The relative expressions of PPARα and PPARδ were negatively associated with tumor size, tumor grade, TNM stage, metastasis, lymphatic invasion, and decreased overall survival time (<i>p</i> &#x3c; 0.05). The same associations, but in reverse direction, were found for PPARγ. <b><i>Conclusions:</i></b> It was found that PPARα and PPARδ were overexpressed while PPARγ was suppressed in CRC tumor tissues, and these deregulations are associated with cancer progression and poor prognosis.

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