Male Nanocontraception: How Nanoparticles Can be Delivered to Testicles for Men’s Birth Control

When it comes to contraceptives, women have the upper hand. There are wide selections of methods and products for female birth control. However, for their male counterparts, there are only two options: condoms or vasectomies. And both have their own sets of drawbacks and margins of errors.

Condoms break and get compromised, while some men are allergic to the latex used in standard condoms. On the other hand, vasectomies are invasive surgical procedures often painful and virtually irreversible.

Hence the search for an alternative male contraceptive option begins. Currently, one method that has drawn attention is nanocontraception.

What is Nanocontraception?

(Photo: Dương Nhân from Pexels)

Nanocontraception is based on the theorized application of nanoparticles. These roughly 100 nanometers in diameter particles one-thousandth of the width of a strand of human hair can be delivered to male testicles and heated up.

If testicles are warmed up, scientists will turn on or off sperm production at will. When the testicle's temperature increases, they become less and less fertile. However, it is a delicate procedure. If the testicles are heated up too much, it can be irreversible. The tissues will die and no longer produce sperm even if the testicles return to normal temperature.

This phenomenon was first studied in 2013 on mice by Fei Sun, a biologist, and a team of multidisciplinary researchers. The team injected nanoparticles directly into the testicles of mouse models. These nanorods were comprised of 120 gold atoms long and 30 gold atoms in diameter that were then coated with special long polymer chains on their surface, looking similarly to oblong bacteria with hairs coming out of them. Infrared radiation was used to heat the mice's testicles. It resulted in nanoparticles warming to about 30 degrees Celsius to 37 & 45 degrees Celsius. The temperature depended on both the intensity of the radiation and the concentration of nanoparticles.

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Recent Findings in Nanocontraception

In July of 2021, Sun's team published their latest findings on the journal NanoLetters, titled "Magnetic Testis Targeting and Magnetic Hyperthermia for Noninvasive, Controllable Male Contraception via Intravenous Administration." In the latest publication, the team nanorods in a new method that comprised of magnetic iron oxide instead of gold atoms in the 2013 study, these were coated in ethylene glycol and citric acid but had the same size and shape as the 2013 nanorods, reports PhysOrg.

The magnetic nanoparticles were then injected into the veins of mice. Then the specimen was anesthetized. Magnets were placed next to the mice's testicles for four hours, which drew the nanoparticles to the area. This procedure was performed daily for up to four days.

After the last day of the treatment, electric coils were wrapped around the mice's testicles, where a current was passed. It induced a temporary magnetic field that heated the nanorods and the testicles. Temperatures increased from a baseline of twenty-nine degrees Celsius to between thirty-seven and forty-two degrees Celsius. The experiment showed that the longer days the mouse was injected with the metallic nanorods, the hotter their testicles became.