Linkage, charge state and layer of L-Cysteine on copper surfaces

Biochemical Behavior, Influence on Cell DNA Condition, and Microbiological Properties of Wool and Wool-Copper Materials

The paper presents the study concerning the preparation and physio-chemical and biological properties of wool-copper (WO-Cu) materials obtained by the sputter deposition of copper onto the wool fibers. The WO-Cu material was subjected to physio-chemical and biological investigations. The physio-chemical investigations included the elemental analysis of materials (C, N, O, S, and Cu), their microscopic analysis, and surface properties analysis (specific surface area and total pore volume). The biological investigations consisted of the antimicrobial activity tests of the WO-Cu materials against colonies of Gram-positive (Staphylococcus aureus) bacteria, Gram-negative (Escherichia coli) bacteria, and fungal mold species (Chaetomium globosum). Biochemical-hematological tests included the evaluation of the activated partial thromboplastin time and pro-thrombin time. The tested wool-copper demonstrated the ability to interact with the DNA in a time-dependent manner. These interactions led to the DNA's breaking and degradation. The antimicrobial and antifungal activities of the WO-Cu materials suggest a potential application as an antibacterial/antifungal material. Wool-copper materials may be also used as customized materials where the blood coagulation process could be well controlled through the appropriate copper content.

Dual functional sites strategies toward enhanced heavy metal remediation: Interlayer expanded Mg-Al layered double hydroxide by intercalation with L-cysteine

The discharge of toxic heavy metals poses a serious threat to human health and environment. The existing water purification systems are lack of promising materials for rapid, efficient, and cost-efficient remediation of numerous toxic heavy metals. Herein, we report on the development of L-cysteine (Cys) intercalated Mg-Al layered double hydroxide (MgAl-LDH/Cys) with a loose lamellar porous architecture as an efficient and economically viable adsorbent for Pb(II) and Cd(II) removal. The intercalation with Cys creates dual functionality, i.e., the interlayer expansion accelerates the diffusion of heavy metals, while Cys acts as additional capture sites for heavy metals. Therefore, remarkable high maximum sorption capacities of 279.58 and 135.68 mg g^-1 for Pb(II) and Cd(II) were obtained for MgAl-LDH/Cys compared to those for pristine MgAl-LDH (30.15 and 36.77 mg g^-1). MgAl-LDH/Cys exhibits also much faster sorption kinetics in comparison with MgAl-LDH. Such enhancements are attributed to the intercalation of the chelating agent Cys in the MgAl-LDH interlayer channels. Moreover, it is proposed that the adsorption mechanisms involve the isomorphous replacement of Mg sites by Cd(II) forming CdAl-LDH, the precipitation of PbS and CdS, and the chelation of sulfhydryl, carboxyl and amine groups toward Cd(II). Altogether, its facile and environmentally friendly fabrication, ultrahigh sorption efficiencies, and rapid kinetics demonstrate that MgAl-LDH/Cys has potential for practical applications in heavy metal remediation.

The Protection Role of Cysteine for Cu-5Zn-5Al-1Sn Alloy Corrosion in 3.5 wt.% NaCl Solution

In this work, the corrosion mechanism of a Cu-5Zn-5Al-1Sn alloy was examined in a 3.5 wt.% NaCl solution. At the same time, the effect of a cysteine inhibitor was also investigated through a multi-analytical approach. Electrochemical results suggested that inhibition efficiency increased with the increase of cysteine concentration. From potentiodynamic polarization (PD) analysis, a decrease in corrosion current and corrosion potential shift toward a more negative direction was observed. The potential difference between the blank and inhibited surface was found to be 46 mV, which is less than 85 mV, revealing a mixed type inhibition effect of cysteine for the Cu-5Zn-5Al-1Sn alloy. The inhibition mechanism of cysteine (Cys) and the effect of alloying elements were investigated by fitting experimental impedance data according to a projected equivalent circuit for the alloy/electrolyte interface. A Langmuir adsorption isotherm was proposed to explain the inhibition phenomenon of cysteine on the Cu-5Zn-5Al-1Sn alloy surface. Surface morphology observation confirmed that the Cu-5Zn-5Al-1Sn alloy was damaged in 3.5 wt.% NaCl solution and could be inhibited by using the cysteine inhibitor. The impact of alloying elements on the corrosion mechanism was further examined by surface analysis techniques such as X-Ray photoelectron spectroscopy (XPS)/Auger spectra, the results of which indicated that the corrosion inhibition was realized by the adsorption of the inhibitor molecules at the alloy/solution interface.