Slightly acidic electrolyzed water (SAEW) is a low-concentration electrolyte solution that is prepared by electrochemical methods. It is widely used in medical care, food safety, pet disinfection and other fields because of its simple preparation, safety, environmental protection and low cost. However, hypochlorous acid water has certain limitations due to its heavy dependence on equipment and severe chlorine loss. In order to improve the stability of HOCL water, chitosan and β-glycerophosphate disodium hydrate were used as gel materials to prepare slightly acidic electrolyzed water thermosensitive gel. The in vitro quality evaluation, antibacterial effect and healing effect on rat skin wounds of the gel were investigated, in order to lay a foundation for the clinical use of hypochlorous acid water thermosensitive gel.
(1) Optimization of the preparation process of slightly acidic electrolyzed water and evaluation of its in vitro antibacterial activity
The effects of hydrochloric acid concentration, electrolysis voltage and acid inlet rate on the quality of slightly acidic electrolyzed water were investigated using pH value, oxidation-reduction potential (ORP) value and available chlorine concentration (ACC) value as indicators, the preparation process of slightly acidic electrolyzed water was optimized, and the in vitro antibacterial activity of the prepared slightly acidic electrolyzed water was evaluated. The results showed that the slightly acidic electrolyzed water prepared when the hydrochloric acid concentration was 5%, the water flow rate was 80 L/h, the electrolysis voltage was adjusted to 5 V, the acid inlet rate was 30 s/time, and the electrolysis time was 30 min had a better quality, with a pH value of 6.42-6.48, an ORP value of 912~920 mv, and an ACC value of 50.30~52.14 μg/mL. After being treated with the HOCL water for 1 min, the survival rates of S. aureus and E. coli were only 6.61% and 5.32%, respectively, indicating the good antibacterial activity of the slightly acidic electrolyzed water.
(2) Preparation of slightly acidic electrolyzed water thermosensitive gel and its effect on in vitro antibacterial activity
The orthogonal experimental design method was used to screen the effects of chitosan concentration, β-glycerophosphate disodium hydrate concentration and the volume ratio of chitosan to β-glycerophosphate disodium hydrate on the gelation time of slightly acidic electrolyzed water thermosensitive gel, and the in vitro antibacterial activity of HOCL water thermosensitive gel was evaluated. The results showed that: with slightly acidic electrolyzed water as the β-glycerophosphate disodium hydrate solvent, a mixed solution of 3% chitosan and 60% β-glycerophosphate disodium hydrate with a volume ratio of 1:1 was fully stirred and mixed under ice bath conditions, and incubated at 37°C for 1 min to obtain slightly acidic electrolyzed water thermosensitive gel. The gel has an opaque gel appearance and has good dissolution properties and long-term water retention properties. The survival rates of S. aureus and E. coli after being treated with the hypochlorous acid water thermosensitive gel were only 2.38% and 0.86%, respectively, showing superior antibacterial activity than anolyte water.
(3) Effect of hydrogel on the stability of the main quality indicators of SAEW water
The prepared slightly acidic electrolyzed water was stored in the conditions of open to light, open to light, sealed to light, and sealed to light for 30 days, and the changes in pH, ORP, and ACC values were investigated. The results showed that HOCL water was most stable under dark and closed storage conditions. After 30 days of storage, the pH and ORP values did not change significantly, and the ACC value only decreased by 28.75%; the stability was poor under light and open storage conditions, and the pH, ORP, and ACC values decreased significantly after 30 days of storage. In order to explore the stability changes of slightly acidic electrolyzed water thermosensitive gel, the changes in the in vitro antibacterial activity of hypochlorous acid water thermosensitive gel and chitosan hydrogel without anolyte water were investigated within 90 days of storage at 4°C. The results showed that EOW water thermosensitive gel always showed better antibacterial activity than chitosan hydrogel within 90 days of storage at 4°C, and its own antibacterial activity did not change significantly, which can indicate that slightly acidic electrolyzed water thermosensitive gel plays a role in extending the service life of hypochlorous acid water and improving the stability of slightly acidic electrolyzed water.
(4) Evaluation of the healing effect of slightly acidic electrolyzed water thermosensitive gel on skin wounds In order to study the healing effect of slightly acidic electrolyzed water thermosensitive gel on skin wounds, a rat skin wound model was constructed, the repair of rat skin wounds was observed, the bacterial load of rat skin wounds was detected, and the contents of interleukin 6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), hydroxyproline (HYP), and myeloperoxidase (MPO) in rat skin wound tissue were investigated. The results showed that slightly acidic electrolyzed water thermosensitive gel had no obvious skin irritation to rats. After only 12 days of treatment, 95.41% of the rat skin wounds healed, which was basically completely healed. The slightly acidic electrolyzed water thermosensitive gel inhibits the expression of inflammatory factors IL-6, IL-1β, and TNF-α in rat skin wound tissue, reduces the content of MPO, and increases the content of HYP, thereby clearing the inflammatory response of rat skin wound tissue, reducing the infiltration of inflammatory cells in wound tissue, promoting the formation of granulation tissue, increasing epidermal thickness, accelerating collagen tissue metabolism and fibrosis, and promoting the healing of rat skin wounds.
The experimental results show that the slightly acidic electrolyzed water thermosensitive gel can improve the stability of slightly acidic electrolyzed water, extend the service life, enhance the antibacterial activity, and promote the healing of rat skin wounds, and can be further used in clinical research. This study has laid a theoretical foundation for the promotion and application of hypochlorous acid water thermosensitive gel.
*The above research is derived from the academic paper: Li Nanxin. Preparation and antibacterial activity evaluation of slightly acidic electrolyzed water thermosensitive gel[D]. Sichuan: Sichuan Agricultural University, 2023.
Antimicrobial Activity Against Bacteria:
Slightly acidic electrolyzed water shows good bactericidal effect on a variety of bacteria. For example, studies have shown that slightly acidic electrolyzed water can effectively kill bacteria such as Escherichia coli, MRSA (methicillin-resistant Staphylococcus aureus), Candida albicans and Staphylococcus aureus.
The HOCL water with different effective chlorine concentrations and redox potentials showed certain differences in the bactericidal effect. When the effective chlorine concentration was ≥75 mg/L and the redox potential was ≥800 mV, its bactericidal effect was no less than that of 75% ethanol and 500 mg/L chlorine-containing disinfectant.
In addition, the study also found that hypochlorous acid water also has a wide range of bactericidal effects on oral microorganisms and is safe for the human body.
Antimicrobial Activity Against Fungi:
Slightly acidic electrolyzed water also exhibits effective antibacterial activity against fungi. For example, studies have shown that anolyte water can reach qualified disinfectant standards for fungal propagules, spores and fungi under specific experimental conditions.
Specifically, neutral anodic solution has a significant inhibitory effect on fungi such as Candida albicans.
Differences between different microorganisms:
There are differences in the sensitivity of slightly acidic electrolyzed water to different types of bacteria. For example, among oral microorganisms, Chlorhexidine shows a high antibacterial effect, while slightly acidic electrolyzed water is effective but not as significant as Chlorhexidine.
For some specific bacteria, such as Staphylococcus aureus, the antibacterial activity of HOCL water is better than Escherichia coli, which may be related to the morphological differences between the two bacteria.
HCLO water exhibits significant antibacterial activity against both bacteria and fungi, but there are certain differences between different types of microorganisms.
Practical application cases of slightly acidic electrolyzed water (SAEW) in food preservation and medical applications include the following aspects:
Food preservation :
Research by Liu Peihong and others shows that by optimizing the parameters of hypochlorous acid water (effective chlorine mass concentration 32 mg/L, soaking time 9 minutes, material-liquid ratio 1:11 g/mL), microorganisms on the surface of fresh rice noodles can be effectively killed , and extend its shelf life by about 16 hours.
Research by Lan Weiqing and others found that ultrasonic combined with slightly acidic electrolyzed water treatment can significantly extend the refrigerated shelf life of vacuum-packed sea bass, by at least 6 days.
Zhou Ran and others used HOCL water combined with chitosan to treat peaches, which can effectively prevent the discoloration of the pulp and extend its shelf life.
Medical:
Pan Qingyan et al. studied a chitosan-based thermosensitive hydrogel and found that it has good biocompatibility and can be used as an injectable local drug delivery carrier for the treatment of periodontal disease.
Wang et al. developed a thermosensitive gel based on hydroxybutyl chitosan for cancer treatment, demonstrating the potential of thermosensitive gels in drug delivery systems.
Bluewav Technology Co., Ltd is specialized in Slightly acidic electrolyzed/HOCL/Anolyte/Hypochlorous acid water, SAEW, diaphragm electrolysis technology is used to produce several types of hypochlorous acid generators such as BHM(common brine electrolysis technology), BHE(medical grade) and BHT(top medical grade). Already exported to America, Philippine, Jordan, Mexico, South Africa, Vietnam, Indonesia...Until now, developed business from China to the World.
