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Nearly half of iNature's global pregnancies are unintended, mainly due to contraceptive failure, which negatively impacts women's health
.
Male contraceptive techniques, primarily condoms and vasectomy, play a vital role in birth control, but are not both efficient and reversible at the same time
.
On March 30, 2022, Xu Wanhai, Wang Hao, Wang Lu and Qiao Zengying of the National Center for Nanoscience and Technology of Harbin Medical University published a joint communication online at ACS Nano (IF=16) entitled "An Ultrasound-Induced Self-Clearance Hydrogel for Male Reversible" Contraception” research paper in which ultrasound (US)-induced self-clearing hydrogels monitored in real time were used for in situ injection into the vas deferens, enabling effective contraception and non-invasive recanalization when needed
.
The hydrogel consists of (i) sodium alginate (SA) combined with reactive oxygen species (ROS) cleavable thioketal (SA-tK), (ii) titanium dioxide (TiO2), which yields specific levels after US treatment ROS and (iii) calcium chloride (CaCl2), which triggers the formation of hydrogels
.
In terms of contraception, the above mixture is injected into the vas deferens at one time, and it can change from liquid to hydrogel within 160s, thereby physically blocking the vas deferens and inhibiting sperm activity
.
When fertility is required, non-invasive ultrasound treatment can generate ROS from TiO2, thereby cleaving SA-tK to disrupt the network of the hydrogel
.
Fertility returns to 100% due to recanalization
.
Meanwhile, diagnostic ultrasound (D-US, 22 MHz) can monitor the occlusion and recanalization process in real time
.
In conclusion, the proposed hydrogel contraception could be a reliable, safe, and reversible male contraceptive strategy that could address the unmet need for male fertility control
.
Unintended pregnancies due to inadequate or lack of family planning expose women to enormous negative impacts and increased risk of death
.
Despite improvements in contraceptive technology, contraceptive failure remains the leading cause of unintended pregnancy worldwide
.
Currently, women still bear the main burden of contraception
.
Many reversible contraceptive methods are widely available, including pills, IUDs, and implants
.
However, these options also come with some side effects, such as venous thromboembolism and abnormal endometrial angiogenesis
.
Male contraceptive methods, primarily condoms and vasectomy, have not seen any significant breakthroughs in nearly 400 years
.
Although vasectomy has shown close to 100% contraceptive efficacy, it remains a challenge due to poor reversibility of vasectomy when fertility is required
.
Therefore, there is an urgent need to develop a simple, feasible and publicly acceptable reversible male contraceptive strategy
.
In recent years, hydrogel materials have been applied to a reversible male contraceptive method called "guided reversible sperm suppression (RISUG)", and clinical trials have been conducted in men
.
The principle of the RISUG strategy is to use a hydrogel to physically block the vas deferens to prevent the passage of sperm, with a contraceptive rate of 97.
3%
.
Unsatisfactorily, the RISUG hydrogel can only be removed by in situ injection of dimethyl sulfoxide (DMSO), a highly toxic organic solvent that can cause some side effects in humans
.
Bao et al.
proposed a near-infrared light-reversible cocktail-type male contraceptive material in which four layers of reagents were sequentially injected into the vas deferens
.
However, this method requires multiple injections, resulting in large doses in the vas deferens and complicated operations
.
In addition, the thermal gel material is also an injectable hydrogel material, which is widely used in the human body
.
However, the gel material undergoes a certain phase transition (from gel-like to sol-like) with changes in ambient temperature, which greatly increases the incidence of unintended pregnancy if vas deferens recanalization occurs unintentionally
.
On the contrary, the ultrasound-responsive hydrogel material can receive ultrasound to control the recanalization of the vas deferens at any time according to people's wishes, which can completely eliminate people's concerns about unintended pregnancy
.
In addition, compared with response methods such as photothermal method, ultrasound has the advantages of strong penetrating ability and no tissue damage, and can trigger sonosensitizers to generate reactive oxygen species, which can effectively achieve non-invasive and reversible male contraception
.
In view of the above speculation, this study developed a safe, non-toxic hydrogel material for male reversible contraception, which can be injected into the vas deferens in a single time, achieving effective contraception and reversible clearance under ultrasound
.
The hydrogel materials include (i) sodium alginate (SA, FDA-approved food-grade raw material), combined with ROS-cleavable thioketal groups (SA-tK), (ii) titanium dioxide (TiO2, a sonosensitizer that can A certain level of ROS is generated after sonication, and (iii) calcium chloride (CaCl2), which triggers the formation of hydrogels
.
The tK groups and SA formed a slightly cross-linked SA-tK in a semi-fluid state, and then the SA-tK aqueous solution (SA-tK/TiO2) containing TiO2 was mixed with CaCl2 to form a hydrogel (SA-tK-Ca2+/TiO2 ), due to the ultrasonic response characteristics of TiO2 in the hydrogel, non-invasive therapeutic ultrasound (R-US, 2W/cm2) can make TiO2 generate ROS, cleavage SA-tK to destroy the structure of the hydrogel, and realize the recanalization of the vas deferens
.
For in vivo evaluation, SA-tK/TiO2 and CaCl2 solutions were injected directly into the bilateral vas deferens of adolescent SD rats for effective contraception
.
During this period, fertility needs can be freely controlled with R-US treatment
.
In addition, D-US can monitor obstruction and recanalization in real time
.
In conclusion, the proposed hydrogel contraception could be a reliable, safe, and reversible male contraceptive strategy that could address the unmet need for male fertility control
.
Reference message: https://pubs.
acs.
org/doi/full/10.
1021/acsnano.
1c09959
.
Male contraceptive techniques, primarily condoms and vasectomy, play a vital role in birth control, but are not both efficient and reversible at the same time
.
On March 30, 2022, Xu Wanhai, Wang Hao, Wang Lu and Qiao Zengying of the National Center for Nanoscience and Technology of Harbin Medical University published a joint communication online at ACS Nano (IF=16) entitled "An Ultrasound-Induced Self-Clearance Hydrogel for Male Reversible" Contraception” research paper in which ultrasound (US)-induced self-clearing hydrogels monitored in real time were used for in situ injection into the vas deferens, enabling effective contraception and non-invasive recanalization when needed
.
The hydrogel consists of (i) sodium alginate (SA) combined with reactive oxygen species (ROS) cleavable thioketal (SA-tK), (ii) titanium dioxide (TiO2), which yields specific levels after US treatment ROS and (iii) calcium chloride (CaCl2), which triggers the formation of hydrogels
.
In terms of contraception, the above mixture is injected into the vas deferens at one time, and it can change from liquid to hydrogel within 160s, thereby physically blocking the vas deferens and inhibiting sperm activity
.
When fertility is required, non-invasive ultrasound treatment can generate ROS from TiO2, thereby cleaving SA-tK to disrupt the network of the hydrogel
.
Fertility returns to 100% due to recanalization
.
Meanwhile, diagnostic ultrasound (D-US, 22 MHz) can monitor the occlusion and recanalization process in real time
.
In conclusion, the proposed hydrogel contraception could be a reliable, safe, and reversible male contraceptive strategy that could address the unmet need for male fertility control
.
Unintended pregnancies due to inadequate or lack of family planning expose women to enormous negative impacts and increased risk of death
.
Despite improvements in contraceptive technology, contraceptive failure remains the leading cause of unintended pregnancy worldwide
.
Currently, women still bear the main burden of contraception
.
Many reversible contraceptive methods are widely available, including pills, IUDs, and implants
.
However, these options also come with some side effects, such as venous thromboembolism and abnormal endometrial angiogenesis
.
Male contraceptive methods, primarily condoms and vasectomy, have not seen any significant breakthroughs in nearly 400 years
.
Although vasectomy has shown close to 100% contraceptive efficacy, it remains a challenge due to poor reversibility of vasectomy when fertility is required
.
Therefore, there is an urgent need to develop a simple, feasible and publicly acceptable reversible male contraceptive strategy
.
In recent years, hydrogel materials have been applied to a reversible male contraceptive method called "guided reversible sperm suppression (RISUG)", and clinical trials have been conducted in men
.
The principle of the RISUG strategy is to use a hydrogel to physically block the vas deferens to prevent the passage of sperm, with a contraceptive rate of 97.
3%
.
Unsatisfactorily, the RISUG hydrogel can only be removed by in situ injection of dimethyl sulfoxide (DMSO), a highly toxic organic solvent that can cause some side effects in humans
.
Bao et al.
proposed a near-infrared light-reversible cocktail-type male contraceptive material in which four layers of reagents were sequentially injected into the vas deferens
.
However, this method requires multiple injections, resulting in large doses in the vas deferens and complicated operations
.
In addition, the thermal gel material is also an injectable hydrogel material, which is widely used in the human body
.
However, the gel material undergoes a certain phase transition (from gel-like to sol-like) with changes in ambient temperature, which greatly increases the incidence of unintended pregnancy if vas deferens recanalization occurs unintentionally
.
On the contrary, the ultrasound-responsive hydrogel material can receive ultrasound to control the recanalization of the vas deferens at any time according to people's wishes, which can completely eliminate people's concerns about unintended pregnancy
.
In addition, compared with response methods such as photothermal method, ultrasound has the advantages of strong penetrating ability and no tissue damage, and can trigger sonosensitizers to generate reactive oxygen species, which can effectively achieve non-invasive and reversible male contraception
.
In view of the above speculation, this study developed a safe, non-toxic hydrogel material for male reversible contraception, which can be injected into the vas deferens in a single time, achieving effective contraception and reversible clearance under ultrasound
.
The hydrogel materials include (i) sodium alginate (SA, FDA-approved food-grade raw material), combined with ROS-cleavable thioketal groups (SA-tK), (ii) titanium dioxide (TiO2, a sonosensitizer that can A certain level of ROS is generated after sonication, and (iii) calcium chloride (CaCl2), which triggers the formation of hydrogels
.
The tK groups and SA formed a slightly cross-linked SA-tK in a semi-fluid state, and then the SA-tK aqueous solution (SA-tK/TiO2) containing TiO2 was mixed with CaCl2 to form a hydrogel (SA-tK-Ca2+/TiO2 ), due to the ultrasonic response characteristics of TiO2 in the hydrogel, non-invasive therapeutic ultrasound (R-US, 2W/cm2) can make TiO2 generate ROS, cleavage SA-tK to destroy the structure of the hydrogel, and realize the recanalization of the vas deferens
.
For in vivo evaluation, SA-tK/TiO2 and CaCl2 solutions were injected directly into the bilateral vas deferens of adolescent SD rats for effective contraception
.
During this period, fertility needs can be freely controlled with R-US treatment
.
In addition, D-US can monitor obstruction and recanalization in real time
.
In conclusion, the proposed hydrogel contraception could be a reliable, safe, and reversible male contraceptive strategy that could address the unmet need for male fertility control
.
Reference message: https://pubs.
acs.
org/doi/full/10.
1021/acsnano.
1c09959
