An approach to give prospective life-span of the copper/low-density-polyethylene nanocomposite intrauterine device

Nanomaterials Solutions for Contraception: Concerns, Advances, and Prospects

Preventing unintentional pregnancy is one of the goals of a global public health policy to minimize effects on individuals, families, and society. Various contraceptive formulations with high effectiveness and acceptance, including intrauterine devices, hormonal patches for females, and condoms and vasectomy for males, have been developed and adopted over the last decades. However, distinct breakthroughs of contraceptive techniques have not yet been achieved, while the associated long-term adverse effects are insurmountable, such as endocrine system disorder along with hormone administration, invasive ligation, and slowly restored fertility after removal of intrauterine devices. Spurred by developments of nanomaterials and bionanotechnologies, advanced contraceptives could be fulfilled via nanomaterial solutions with much safer and more controllable and effective approaches to meet various and specific needs for women and men at different reproductive stages. Nanomedicine techniques have been extended to develop contraceptive methods, such as the targeted drug delivery and controlled release of hormone using nanocarriers for females and physical stimulation assisted vasectomy using functional nanomaterials via photothermal treatment or magnetic hyperthermia for males. Nanomaterial solutions for advanced contraceptives offer significantly improved biosafety, noninvasive administration, and controllable reversibility. This review summarizes the nanomaterial solutions to female and male contraceptives including the working mechanisms, clinical concerns, and their merits and demerits. This work also reviewed the nanomaterials that have been adopted in contraceptive applications. In addition, we further discuss safety considerations and future perspectives of nanomaterials in nanostrategy development for next-generation contraceptives. We expect that nanomaterials would potentially replace conventional materials for contraception in the near future.

Recent progress in advanced biomaterials for long-acting reversible contraception

Unintended pregnancy is a global issue with serious ramifications for women, their families, and society, including abortion, infertility, and maternal death. Although existing contraceptive strategies have been widely used in people's lives, there have not been satisfactory feedbacks due to low contraceptive efficacy and related side effects (e.g., decreased sexuality, menstrual cycle disorder, and even lifelong infertility). In recent years, biomaterials-based long-acting reversible contraception has received increasing attention from the viewpoint of fundamental research and practical applications mainly owing to improved delivery routes and controlled drug delivery. This review summarizes recent progress in advanced biomaterials for long-acting reversible contraception via various delivery routes, including subcutaneous implant, transdermal patch, oral administration, vaginal ring, intrauterine device, fallopian tube occlusion, vas deferens contraception, and Intravenous administration. In addition, biomaterials, especially nanomaterials, still need to be improved and prospects for the future in contraception are mentioned.

Copper nanoparticle-induced uterine injury in female rats

Copper nanoparticles (Cu-NPs) have been used increasingly in various products and applications. Although recent studies have reported that exposure to Cu-NPs leads to organ accumulation and obvious toxicity, it remains unclear whether Cu-NPs can be translocated to and cause damage in the uterus. In this study, we investigated the potential for uterine injury and gene expression patterns in female rats exposed to 3.12, 6.25, or 12.5 mg/kg/d Cu-NPs via intraperitoneal injection for 14 consecutive days. The results indicated that exposure to Cu-NPs led to significant decreases in the relative uterine weight coefficients and increases in inflammatory cell infiltration, mitochondrial swelling and vacuolization, shortened and reduced endometrial epithelial cell microvilli, and apoptosis. Furthermore, exposure to Cu-NPs increased malondialdehyde (MDA) accumulation and decreased superoxide dismutase (SOD) levels. Signal transduction mechanism studies indicated that exposure to Cu-NPs activated caspases 3, 8, and 9 and BH3 interacting domain death agonist (tBid), reduced B cell leukemia/lymphoma 2 (Bcl-2) expression, and increased the expression of apoptotic peptidase activating factor 1 (Apaf-1), BCL2-associated X, apoptosis regulator (Bax), and cytochrome c. A microarray analysis revealed significant alterations in the expression of 963 genes; of these, 622 were upregulated and 341 were downregulated. The results of further evaluations of some altered genes, including matrix metallopeptidase 12 (Mmp12), using quantitative RT-PCR agreed with the microarray findings. These results provide strong evidence that Cu-NPs can trigger both intrinsic and extrinsic apoptotic pathways to mediate uterine injury, resulting in oxidative stress-related changes in gene expression.

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.

Antibacterial and non-cytotoxic effect of nanocomposites based in polyethylene and copper nanoparticles

In this study, an antibacterial, but not cytotoxic nanomaterial based on polyethylene and copper nanoparticles was prepared by in situ polymerization. PE-CuNps nanocomposites against Escherichia coli, completely suppressed the number of live bacteria after 12 h incubation compared to neat PE. TEM images showed that nanocomposites damage the plasma membrane of the bacteria, revealing a bacteriolytic effect. Toxic effects of copper nanoparticles on viability of neuroblastoma line cell also was evaluated, revealing a non cytotoxic effect for the doses used, showing that this nanocomposite is a ideal material for medical devices.

Applying emerging science to contraception research: implications for the clinic

Emerging science will make an important contribution towards the development of improved contraceptives. While long-acting reversible contraceptives remain the most effective method, new user-controlled, mid-acting methods will avoid the need for procedures requiring trained providers. Contraceptives combined with other agents may bring additional health benefits, such as dual protection against both pregnancy and sexually transmitted infections. Emerging research areas in proteomics allowed the discovery of new reproductive targets that may lead to non-hormonal contraceptives for both men and women. Current research objectives include the improvement of existing contraceptive methods, as well as discovery of new materials able to deliver new molecules more specifically to their target without systemic actions.

Alterations in the endometrium of rats, rabbits, and Macaca mulatta that received an implantation of copper/low-density polyethylene nanocomposite

A copper/low-density polyethylene nanocomposite (nano-Cu/LDPE), a potential intrauterine device component material, has been developed from our research. A logical extension of our previous work, this study was conducted to investigate the expression of plasminogen activator inhibitor 1 (PAI-1), substance P (SP), and substance P receptor (SP-R) in the endometrium of Sprague Dawley rats, New Zealand White rabbits, and Macaca mulatta implanted with nano-Cu/LDPE composite. The influence of the nano-Cu/LDPE composite on the morphology of the endometrium was also investigated. Animals were randomly divided into five groups: the sham-operated control group (SO group), bulk copper group (Cu group), LDPE group, and nano-Cu/LDPE groups I and II. An expression of PAI-1, SP, and SP-R in the endometrial tissues was examined by immunohistochemistry at day 30, 60, 90, and 180 postimplantation. The significant difference for PAI-1, SP, and SP-R between the nano-Cu/LDPE groups and the SO group (P<0.05) was identified when the observation period was terminated, and the changes of nano-Cu/LDPE on these parameters were less remarkable than those of the Cu group (P<0.05). The damage to the endometrial morphology caused by the nano-Cu/LDPE composite was much less than that caused by bulk copper. The nano-Cu/LDPE composite might be a potential substitute for conventional materials for intrauterine devices in the future because of its decreased adverse effects on the endometrial microenvironment.

Biological evaluation of the copper/low-density polyethylene nanocomposite intrauterine device

Devices and materials intended for clinical applications as medical and implant devices should be evaluated to determine their biocompatibility in physiological systems. This article presents results from cytotoxicity assay of L929 mouse fibroblasts culture, tests for skin irritation, intracutaneous reactivity and sensitization, and material implantation tests for the novel copper/low-density polyethylene nanocomposite intrauterine device (nano-Cu/LDPE IUD) with potential for future clinical utilization. Cytotoxicity test in vitro was conducted to evaluate the change in morphology, growth and proliferation of cultured L929 mouse fibroblasts, which in vivo examination for skin irritation (n = 6) and intracutaneous reactivity (n = 6) were carried out to explore the irritant behavior in New Zealand White rabbits. Skin sensitization was implemented to evaluate the potential skin sensitizing in Hartley guinea pigs (n = 35). The materials were implanted into the spinal muscle of rabbits (n = 9). The cytotoxicity grade of the nano-Cu/LDPE IUD was 0-1, suggested that the composite was nontoxic or mildly cytotoxic; no irritation reaction and skin sensitization were identified in any animals of specific extracts prepared from the material under test; similarly to the control sides, the inflammatory reaction was observed in the rabbits living tissue of the implanted material in intramuscular implantation assay. They indicated that the novel composite intrauterine device presented potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity. The nano-Cu/LDPE IUD has good biocompatibility, which is biologically safe for the clinical research as a novel contraceptive device.

A porous Cu/LDPE composite for copper-containing intrauterine contraceptive devices

To improve the rates of both cupric ion release and the utilization of copper in non-porous copper/low-density polyethylene (Cu/LDPE) composite, a porous Cu/LDPE composite is proposed and developed in the present work. Here 2,5-di-tert-butylhydroquinone was chosen as the porogen, ethyl acetate was chosen as the solvent for extraction, and the porous Cu/LDPE composite was obtained by using injection molding and the particulate leaching method. After any residual ethyl acetate remaining inside the porous Cu/LDPE composite had been removed by vacuum drying, the composite was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry and absorption measurement. For comparison, a non-porous Cu/LDPE composite was also characterized in the same way. The results show that the porous structure was successfully introduced into the polymeric base of the non-porous Cu/LDPE composite, and the porous Cu/LDPE composite is a simple hybrid of copper particles and porous LDPE. The results also show that the introduction of a porous structure can improve the cupric ion release rate of the non-porous Cu/LDPE composite with a certain content of copper particles, indicating that the utilization rate of copper can be improved either the introduction of a porous structure, and that the porous Cu/LDPE composite is another promising material for copper-containing intrauterine devices.