Decrease in cytotoxicity of copper-based intrauterine devices (IUD) pretreated with 6-mercaptopurine and pterin as biocompatible corrosion inhibitors

The Levonorgestrel-Releasing Intrauterine Device as Emergency Contraception: Re-examining the Data

Emergency contraception methods that also deliver ongoing contraception provide the most effective options for individuals hoping to prevent pregnancy after unprotected intercourse. Although the copper intrauterine device (IUD) provides the most effective option for emergency contraception because the device prevents pregnancy when placed before implantation and offers long-acting contraception, uptake by patients has been limited. Recently, the Society of Family Planning issued new guidance recommending the levonorgestrel IUD (LNG-IUD) as an emergency contraception option along with the copper IUD. Here, we review evidence related to this recommendation and conclude that the available data do not support use of the LNG-IUD for emergency contraception. We discuss the mechanisms of action of emergency contraception methods and how these concepts interface with the current political and social landscape of contraception and abortion care. We describe limitations of the existing evidence supporting use of the LNG-IUD as emergency contraception and highlight the critical research needed to establish the device as a highly effective method of emergency contraception.

Density functional theory study of the corrosion inhibition performance of 6-mercaptopurine and 6-thioguanine expired drugs toward the aluminium (111) surface

The potentiality of the 6-mercaptopurine (MP) and 6-thioguanine (TG) expired drugs toward the corrosion inhibition of the aluminium (Al) (111) surface was widely investigated using a series of density functional theory (DFT) calculations. A competition between the anti-corrosive features of the studied drugs in the gas and aqueous phases was conducted on both neutral and protonated forms by means of quantum mechanical descriptors. The results of the electrostatic potential analysis demonstrated the prominent nucleophilic nature of the sulfur and nitrogen atoms over the structures of the examined drugs. The frontier molecular orbital theory findings outlined the higher preferability of TG over MP as a corrosion inhibitor. Upon determining the most beneficial configurations of the MP/TG⋯Al (111) complexes, first-principles molecular dynamics simulations were executed. Interestingly, the competence of the TG drug in the corrosion inhibition process of Al (111) was more extensive than that of the MP one, which was confirmed by the interaction energy values of -1.79 and -1.64 eV, respectively. Upon obtaining the relaxed complexes, the effect of the presence of water solvent on the adsorption process was studied. These findings provide a foundation for developing green anti-corrosive inhibitors for the aluminium surface.

Sensing a CO-Releasing Molecule (CORM) Does Not Equate to Sensing CO: The Case of DPHP and CORM-3

Carbon monoxide (CO) is an endogenous signaling molecule with demonstrated pharmacological effects. For studying CO biology, there is a need for sensitive and selective fluorescent probes for CO as research tools. In developing such probes, CO gas and/or commercially available metal-carbonyl-based "CO-releasing molecules" (CORMs) have been used as CO sources. However, new findings are steadily emerging that some of these commonly used CORMs do not release CO reliably in buffers commonly used for studying such CO probes and have very pronounced chemical reactivities of their own, which could lead to the erroneous identification of "CO probes" that merely detect the CORM used, not CO. This is especially true when the CO-sensing mechanism relies on chemistry that is not firmly established otherwise. Cu2+ can quench the fluorescence of an imine-based fluorophore, DPHP, presumably through complexation. The Cu2+-quenched fluorescence was restored through the addition of CORM-3, a Ru-based CORM. This approach was reported as a new "strategy for detecting carbon monoxide" with the proposed mechanism being dependent on CO reduction of Cu2+ to Cu1+ under near-physiological conditions ( Anal. Chem. 2022, 94, 11298-11306). The study only used CORM-3 as the source of CO. CORM-3 has been reported to have very pronounced redox reactivity and is known not to release CO in an aqueous solution unless in the presence of a strong nucleophile. To assess whether the fluorescent response of the DPHP-Cu(II) cocktail to CORM-3 was truly through detecting CO, we report experiments using both pure CO and CORM-3. We confirm the reported DPHP-Cu(II) response to CORM-3 but not pure CO gas. Further, we did not observe the stated selectivity of DPHP for CO over sulfide species. Along this line, we also found that a reducing agent such as ascorbate was able to induce the same fluorescent turn-on as CORM-3 did. As such, the DPHP-Cu(II) system is not a CO probe and cannot be used to study CO biology. Corollary to this finding, it is critical that future work in developing CO probes uses more than a chemically reactive "CO donor" as the CO source. Especially important will be to confirm the ability of the "CO probe" to detect CO using pure CO gas or another source of CO.

Electrochemical Analysis of the Influence of Purines on Copper, Steel and Some Other Metals Corrosion

Metals stability and corrosion resistance are very important factors that influence the possibility of their applications. In order to study and foresee the behavior of metals during various applications in all kinds of conditions and media, numerous approaches and techniques are developed and applied. Among those techniques, electrochemical measurements nowadays have a dominant role since they are proved to be highly efficient, reliable, fast, relatively low-cost, and easy regarding the preparation and execution of measurements. Besides that, they also provide quite a good amount of data regarding the effect and the mechanism of the reactions that metals interact in. Metals corrosion is reduced by various methods, one of the most frequently used ones is the application of corrosion inhibitors. Usually, organic compounds are studied as potential corrosion inhibitors, and at the moment the focus is on the effect on the environment. Hence, environmentally friendly and non-toxic inhibitors are important research topics. Purines, since they are the group of bioorganic compounds found in numerous biochemical structures such as DNA and RNA, present a very interesting possible solution and are studied as inhibitors of corrosion for copper, steel, aluminum, etc., as well as for some metal alloys. Data obtained and available up until the present are presented and discussed in this review.

Effective easing of the side effects of copper intrauterine devices using ultra-fine-grained Cu-0.4Mg alloy

Copper intrauterine device is one of the most adopted contraceptive methods with high effectiveness (over 99 %), low cost, spontaneous reversibility and long-lasting usage. However, the side effects induced from the initial burst release of copper ions (Cu²⁺) hinder the continuation of the Cu-IUD made of Coarse-Grained Copper (CG Cu). We proposed to tailor the bio-corrosion behaviors of better control of Cu²⁺ release via the addition of bioactive Mg into the Ultra-Fine Grained (UFG) Bulk Cu. Thus, UFG bulk Cu with 0.4 wt.% Mg was produced via equal-channel angular pressing. The microstructures of the UFG Cu-0.4Mg was observed using electron backscatter diffraction and transmission electron microscopy techniques. The in vitro long-term corrosion behaviors in simulated uterine fluid, cytotoxicity to four cell lines, in vivo biocompatibility and contraceptive efficacy were all studied on CG Cu, UFG Cu and UFG Cu-0.4Mg materials. The results demonstrate that both the ultrafine grains and the addition of bioactive Mg into Cu contribute to the suppression of the burst release of Cu²⁺ in the initial stage and the maintenance of high level Cu²⁺ in long-term release. Moreover, the UFG Cu-0.4Mg also exhibited much improved cell and tissue biocompatibility from both the in vitro and in vivo evaluations. Therefore, the contraceptive efficacy of UFG Cu-0.4Mg is still maintained as high as the CG Cu and UFG Cu while the side effects are significantly eased, suggesting the high potential of the UFG Cu-0.4Mg alloy as a new upgrading or alternative material for Cu-IUD. STATEMENT OF SIGNIFICANCE: The side effects from burst release of Cu²⁺ at the initial implantation stage of Cu-containing intrauterine devices (Cu-IUD) is one of the main drawbacks of these devices. In this work, an ultra-fine-grained Cu (UFG Cu) alloyed with a low amount of bioactive Mg was used for a Cu-IUD. The UFG Cu-0.4Mg alloy exhibited suppressed burst release of Cu²⁺ at initial implantation, while active Cu²⁺ release for long-term usage was maintained, comparable to coarse-grained pure Cu. Furthermore, the UFG Cu-0.4Mg alloy displayed significantly improved biocompatibility with human uterus cells and a much decreased inflammatory response within the uterus. Therefore, the side effects from Cu-IUD were eased, while high antifertility efficacy of the UFG Cu-0.4Mg alloy was maintained. The UFG Cu-0.4Mg alloy is promising for Cu-IUD.

Ibuprofen as a corrosion inhibitor for copper in synthetic acid rain solution

It is known that if unused drugs are improperly disposed, they can pollute the environment. Furthermore, researchers are still trying to find an environmentally friendly corrosion inhibitor. These factors lead to the possible application of unused pharmaceutical compounds as corrosion inhibitors. The feasibility of an anti-inflammatory, analgesic and antipyretic drug, ibuprofen, was evaluated as a potential copper corrosion inhibitor in synthetic acid rain solution. This investigation was performed by applying electrochemical and weight loss measurements and quantum chemical calculations. The results obtained by these techniques revealed the ability of ibuprofen to protect copper from corrosion. The inhibition efficiency of ibuprofen rises with increase in its concentration and can reach a value of 97.3%. The results of surface analysis of treated coupons by scanning electron microscopy and theoretical calculations are consistent with the experimental results.

Green synthesis of a plant-derived protein protected copper quantum cluster for intrauterine device application

Fluorescent copper quantum clusters (CuQCs) have received great interest in recent times due to their attractive features, such as water solubility, low cost, wide availability of Cu and good biocompatibility. Recently, considerable efforts have been devoted to the preparation and applications of CuQCs. Herein, we report a simple one-pot green method for the preparation of fluorescent CuQCs using a plant-derived protein, gluten, as a stabilizing agent. Gluten, a naturally abundant, low-cost and sustainable plant-protein derived from wheat, was employed both as a reducing and stabilizing agent to produce blue emitting CuQCs. The CuQCs were characterized by UV-Vis absorption, fluorescence, FT-IR, TEM, and XPS. We further incorporated CuQCs into a polymer to study the release rate of Cu2+ ions from a CuQC-polymer composite, since copper ions are well known for their fungicidal properties and contraceptive action in copper-T (CuT). The CuQCs were incorporated into a model polymer, polyurethane (PU), by melt compounding, and the mixtures were extruded in the form of a wire. It was observed that the CuQCs were uniformly dispersed within the polymer matrix. An in vitro experiment was carried out to quantify the potential release of Cu(ii) ions for contraceptive applications. The developed nanocomposite releases Cu(ii) ions for 90 days, which suggests the potential application of the CuQCs in the medical field like the development of short-term intrauterine devices (IUDs). Compared to conventional IUDs, here the CuQC-PU nanocomposite reduces the burst release of the Cu2+, and the release rates can be tuned by changing the composition of the materials. These results suggest that the CuQC-PU nanocomposites have great potential to replace current commercial intrauterine devices.

Studies of acute and subchronic systemic toxicity associated with a copper/low-density polyethylene nanocomposite intrauterine device

Introduction

The physiologic safety of devices and materials intended for clinical implantation should be evaluated. This study, a logical extension of our previous work, aimed to investigate the safety of a novel contraceptive device, the copper/low-density polyethylene nanocomposite intrauterine device (nano-Cu/LDPE IUD), through studies of its potential toxicity after acute and subchronic administration in mice and rats.

Methods

For the acute toxicity study, single 50 mL/kg doses of nano-Cu/LDPE IUD extracts were administered to mice via intravenous or intraperitoneal injection. General behavioral adverse effects, mortality, and body weights were evaluated for up to 72 hours. In the 13-week subchronic toxicity study, the nano-Cu/LDPE composite with 10-fold higher than the standard clinical dose was implanted subcutaneously into the dorsal skin of Wistar rats. The control group underwent a sham procedure without material insertion.

Results

During all acute study observation times, the biologic reactions of the mice in the nano-Cu/LDPE group did not differ from those observed in the control group. The groups did not differ statistically in terms of body weight gain, and no macroscopic changes were observed in any organs. In the subchronic study, no clinical signs of toxicity or mortality were observed in either the nano-Cu/LDPE or control group during the 13-week period. The nano-Cu/LDPE composite did not cause any alterations in body weight, food consumption, hematologic and biochemical parameters, or organ weight relative to the control for any observed sample group. Histopathologic examinations of the organs revealed normal architecture, indicating that the inserted material did not cause morphologic disturbances in the rats.

Conclusion

Overall, the results indicate that the nano-Cu/LDPE IUD did not induce systemic toxicity under experimental conditions of the recommended standard practices, suggesting that the novel material IUD is safe and feasible for future contraceptive applications.

Reduction of copper ions release by a novel ecofriendly electropolymerized nanolayer obtained from a natural compound (carvacrol)

The release of copper ions by copper-containing devices, equipments and facilities represents a potential risk for biological systems. Different inhibitory treatments (CuIT) that use organic compounds have been proposed to reduce this environmental hazard but many of them are not in accordance with new regulations. The development of an ecofriendly CuIT based on the use of carvacrol, a natural phenolic compound present in essential oils, is reported here. The effects of carvacrol adsorption (adCarv) and its electropolymerization (polyCarv) were examined. Electropolymerization was attained after cycling the copper electrode in the 0.3-1.0V potential range. Electrochemical techniques complemented by ATR-FTIR, XPS, SEM and AFM surface analyses were used to evaluate the composition and characteristics of the layers. Results demonstrated that adCarv includes cetonic structures while polyCarv additionally contains ether bonds. AFM and SEM observations showed the presence of round nanoglobules, larger for adCarv (close to 50nm diameter). Cytotoxicity of adCarv and polyCarv layers on copper was also evaluated. The comparative analysis of both treatments revealed that polyCarv nanolayer is highly protective while the adCarv layer is weakly protective and reduction in cell viability was found. It was concluded that CuIT that leads to polyCarv nanolayer is very effective and ecofriendly.

A reversible fluorescence chemosensor for sequentially quantitative monitoring copper and sulfide in living cells

We report a novel, selective and sensitive strategy for the sequentially "ON-OFF-ON" fluorescent detection of Cu(2+) and S(2-) based on a fluorescein derivative, FL. The specific binding of FL towards Cu(2+) in aqueous and biological media led to the intensive green fluorescence quenching and a notable increase of the absorbance maximum at 480 nm. In the presence of S(2-), the intensity and overall pattern of the fluorescence emission and UV-vis spectra of FL-Cu(2+) ensemble were recovered since the abolishment of paramagnetic Cu(2+). This displacement approach exhibited highly specificity, and sensitivity with detection limits of 3 nM for Cu(2+) and 150 nM for S(2-). The fluorescence "ON-OFF-ON" circle can be repeated to a minimum of 5 times by the alternative addition of Cu(2+) and S(2-), implying that FL is a renewable dual-functional chemosensor. The biocompatibility of FL toward breast carcinoma cells, MDA-MB-231 was confirmed by MTT assay. The reversible "ON-OFF-ON" fluorescent response of FL to Cu(2+) and S(2-) in living system was further confirmed by confocal fluorescence imaging of living cells. The quantification of Cu(2+) and S(2-) in single intact cell was realized by the flow cytometry analysis.

Photodynamic inactivation induced by carboxypterin: a novel non-toxic bactericidal strategy against planktonic cells and biofilms of Staphylococcus aureus

Microbial related contamination is of major concern and can cause substantial economic losses. Photodynamic inactivation (PDI) has emerged as a suitable approach to inhibit microorganism proliferation. In this work, PDI induced by 6-carboxypterin (Cap), a biocompatible photosensitizer (PS), was analyzed. The growth inhibition of Staphylococcus aureus exposed to artificial UV-A radiation and sunlight in the presence of Cap was investigated. After UV-A irradiation, 50 μM Cap was able to decrease by three orders (with respect to the initial value) the number of S. aureus cells in early biofilms. However, this concentration was 500 times higher than that needed for eradicating planktonic cells. Importantly, under solar exposure, 100 μM Cap was able to suppress sessile bacterial growth. Thus, this strategy is able to exert a bactericidal effect on sessile bacteria and to eradicate planktonic cells by exposing the Cap-containing sample to sunlight.

Controllable preparation of graphene oxide/metal nanoparticle hybrids as surface-enhanced Raman scattering substrates for 6-mercaptopurine detection

In this contribution, a new simple and cost-effective strategy for the preparation of hybrids of graphene oxide (GO) and metal nanoparticles (MNPs) through the mediation of polyethyleneimine (PEI) molecules was reported.