- The hybrid materials based on metal nanoparticles (Ag, Cu) combined with chitosan and octenidine have been successfully synthesized.

- The applicability of the synthesized hybrid materials in veterinary medicine for mastitis prevention has been successfully assessed with positive results.

Theoretical results: 

- The Cu/Cts material has been successfully synthesized via an environmentally friendly chemical reduction method employing the reducing agent extracted from guava leaves. The utilization of guava leaves as the reducing agent has exhibited remarkable selective reducing capabilities. The Cu nanoparticles are formed in a single-phase metallic state, with dimensions ranging from 20 to 40 nm. Additionally, the results indicate that when a stronger reducing agent, namely NaBH4, is utilized, the Cu nanoparticles exhibit larger sizes, approximately ranging from 10 to 30 nm, predominantly existing in spherical morphology. Upon the application of Octenidine to both materials, there were no alterations observed in their shape or structure; however, a slight increase in size was evident.

- The evaluation results of the antibacterial activity against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 13709), bacteria causing mastitis in dairy cows, demonstrate that both Cu/Cts and Cu/Cts-Otd materials exhibit excellent inhibitory activity. At a sample concentration of 500 mg/ml, Cu/Cts material employing guava leaf extract (Cu/Cts-Lá Vối) as the reducing agent exhibits superior antibacterial inhibitory activity against gram-positive bacterium Staphylococcus aureus (with a bacterial inhibition zone diameter of 20 mm) compared to Cu/Cts material utilizing NaBH4 (Cu/Cts-NaBH4) as the reducing agent (with a bacterial inhibition zone diameter of 18 mm). However, regarding gram-negative bacterium Escherichia coli, the results indicate a reverse trend, with Cu/Cts-Lá Vối showing lower inhibitory efficiency compared to Cu/Cts-NaBH4 (with bacterial inhibition zone diameters of 18 mm and 22 mm, respectively). Both Cu/Cts/Lá Vối and Cu/Cts/NaBH4 materials, when treated with 5% Octenidine, exhibit very good antibacterial inhibitory activity against gram-positive bacterium Staphylococcus aureus (ATCC 13709). At a sample concentration equal to 125 mg/ml, Cu/Cts/Otd-5-Lá Vối material with a bacterial inhibition zone diameter of 22 mm demonstrates better antibacterial inhibitory activity compared to Cu/Cts/Otd-5-NaBH4 material with a bacterial inhibition zone diameter of 18 mm.

- The Ag/Cts and Ag/Cts/Otd materials synthesized with a concentration of 5% Octenidin exhibit spherical morphology, with sizes ranging from 10 to 14 nm uniformly distributed on the Chitosan/Octenidin surface. The inhibitory activity test results against Staphylococcus aureus (ATCC 13709), a gram-positive bacterium causing mastitis in dairy cows, demonstrate that both Ag/Cts and Ag/Cts-Otd samples exhibit superior inhibitory activity compared to the control sample using distilled water instead of an antibacterial agent. This is evidenced by a 2-2.5 fold increase in the diameter of the bacterial inhibition zone. Furthermore, the results also indicate that the bactericidal ability decreases with decreasing sample concentration, with a dilute concentration of 1/20 resulting in a reduction of the bacterial inhibition zone diameter from 15 to 12 mm for Ag/Cts samples and from 15 to 13 mm for Ag/Cts/Otd samples. Additionally, the addition of Octenidin does not significantly improve the bactericidal ability of the Ag/Cts material.

Applied results: The hybrid Ag, Cu/Chitosan-Octenidine materials have been successfully tested for their antibacterial properties, demonstrating excellent inhibitory activity against Staphylococcus aureus and Escherichia coli, the bacteria causing mastitis in dairy cows.

- Establishing and fostering international cooperation with Belarusian scientists in the field of science and technology for the fabrication of nanoscale materials applied in medicine (veterinary medicine).

- Contributing further to the field of materials science with novel hybrid materials based on the utilization of Ag, Cu/Chitosan-Octenidine nanostructures for antibacterial applications.

- Publications: 

Phuong Anh Pham, Doan Thi Hai, Nguyen Thi Nhiem, Nguyen Minh Viet, Quoc Anh Ngo, Viktoryia Kulikouskaya and Quang Vinh Tran. Synthesis and antibacterial activity of metallic copper-chitosan nanomaterial using environmentally friendly Cleistocalyx Operculatus leaf extract as a reducing agent, Vietnam Journal of Chemistry, 2024, 62(S1) 139-146.

DOI: 10.1002/vjch.202300277.

- Other products: Successful education of one bachelor.

The results of the project continue to be further researched and applied in practical treatments for various bacterial diseases affecting livestock and poultry, contributing to the development of sustainable agriculture.