Tổng hợp nano cu2o cu alginate và khảo sát khả năng kháng nấm neoscytalidium dimidiatum gây bệnh đốm nâu trên cây thanh long

BỘ GIÁO DỤC VÀ ĐÀO TẠO HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ - Nguyễn Duy Thắng TỔNG HỢP NANO CU2O-CU/ALGINATE VÀ KHẢO SÁT KHẢ NĂNG KHÁNG NẤM NEOSCYTALIDIUM DIMIDIATUM GÂY BỆNH ĐỐM NÂU TRÊN CÂY THANH LONG LUẬN VĂN THẠC SĨ: HÓA HỌC Thành phố Hồ Chí Minh- 2021 BỘ GIÁO DỤC VÀ ĐÀO TẠO HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ - Nguyễn Duy Thắng TỔNG HỢP NANO CU2O-CU/ALGINATE VÀ KHẢO SÁT KHẢ NĂNG KHÁNG NẤM NEOSCYTALIDIUM DIMIDIATUM GÂY BỆNH ĐỐM NÂU TRÊN CÂY THANH LONG Chuyên ngành: Hóa vô Mã số: 8440113 LUẬN VĂN THẠC SĨ: HÓA HỌC NGƯỜI HƯỚNG DẪN KHOA HỌC Hướng dẫn : TS Bùi Duy Du Thành phố Hồ Chí Minh - 2021 Lời cam đoan Tôi xin cam đoan là công trình nghiên cứu của sự hướng dẫn khoa học của TS Bùi Duy Du Các nội dung nghiên cứu, kết quả đê tài là trung thực, chưa được công bố ở các đê tài cùng cấp và các công trình khoa học tương tự Tp Hồ Chí Minh, tháng 02 năm 2021 Học viên cao học Nguyễn Duy Thắng i Lời cảm ơn Để hoàn thành luân văn này, xin gửi lời cảm ơn chân thành đến: TS Bùi Duy Du, thầy đã hướng dẫn tận tình, tạo điêu kiện cho vê sở vật chất, thiết bị và địa điểm để thực hiện và hoàn thành luận văn NCS Lê Nghiêm Anh Tuấn, thầy đã giúp đỡ và hướng dẫn quá trình làm thí nghiệm và hoàn thiện nội dung luận văn Trung tâm sinh học và vật liệu – Viện Khoa học Vật Liệu ứng dụng, phòng thí nghiệm trọng điểm vê Công nghệ Tế bào Thực vật – Viện Sinh học nhiệt đới, đã cung cấp sở hạ tầng, trang thiết bị giúp thực hiện các thí nghiệm Học viện Khoa học và Công nghệ – Viên Hàn lâm Khoa học và Công nghệ Việt Nam đã hỗ trợ tạo mọi điêu kiện giúp hoàn thành tốt chương trình đào tạo Thạc sĩ và hoàn thành luận văn này Các bạn học viên lớp cao học Hóa vô và Hóa phân tích khóa 2017A và 2017B đã động viên giúp đỡ suốt hóa trình học tập cũng thực hiện luận văn ii DANH MỤC CÁC KÝ HIỆU VÀ CHỮ VIẾT TẮT STT 10 11 12 iii DANH MỤC CÁC BẢNG Bảng 1.1 Các công nghệ khác sử dụng cho việc điêu chế hạt nano Cu2O .14 Bảng 3.1 Ảnh hưởng của nồng độ alginate đến kích thước hạt nano Cu2O-Cu 41 Bảng 3.2 Độc tính cấp LD50 qua đường miệng chuột của chế phẩm nano Cu2O Cu/alginate 47 Bảng 3.3 Tỷ lệ nhạy cảm của chuột với chế phẩm nano Cu2O-Cu/alginate 48 Bảng 3.4 Sự thay đổi khối lượng thể và phản ứng nhạy cảm da 48 Bảng 3.5 Hiệu lực ức chế nấm Neoscytalidium dimidiatum của chế phẩm nano Cu2O-Cu/alginate 51 Bảng 3.6 Tỉ lệ bệnh và chỉ số bệnh đốm nâu long thí nghiệm điêu kiện nhà lưới 53 Bảng 3.7 Hiệu lực phòng trừ bệnh đốm nâu cành long ở thí nghiệm điêu kiện nhà kính 54 iv DANH MỤC CÁC HÌNH VẼ, ĐỒ THỊ Hình 1.1 Đặc trưng cấu trúc của alginate Hình 1.2 Mơ hình tạo gel của alginate với ion hóa trị Hình 1.3 Triệu chứng bệnh đớm nâu dây, quả long nấm Neoscytalidium dimidiatum gây Hình 1.4 Hình ảnh chụp các hạt nano đồng tương tác lên tế bào vi khuẩn, phá vỡ cấu trúc màng ngoài của tế bào vi khuẩn và tiêu diệt chúng Hình 1.5 Cơ chế phòng trừ vi sinh vật của CuO và Cu2O (Surapaneni Meghana et al, 2013) 10 Hình 1.6 Độc tính của các chất và hợp chất kim loại nano so với muối kim loại của nó (Nguồn: Olesja Bondarenko cs, 2013) 17 Hình 2.1 Quy trình điêu chế vật liệu Cu2O-Cu/alginate 21 Hình 2.2 Thiết bị kính hiển vi điện tử truyên qua JEM 1400; JEOL - Nhật Bản 22 Hình 2.3 Sơ đờ nhiễu xạ của tia X tinh thể 23 Hình 2.4 Góc đỉnh phản xạ của tía X phụ thuộc kích thước hạt 24 Hình 2.5 Nhiễu xạ tia X (D8-ADVANCE, Brucker – Đức) 24 Hình 2.6 Thiết bị hồng ngoại FT–IR 8400S (Shimadzu - Nhật Bản) 25 Hình 2.7 Thiết bị UV- Vis Model V630, Jasco - Nhật Bản 27 Hình 2.8 Kính hiển vi điện tử quét phân giải cao với hệ tán xạ lượng tia X (JSM-7610 - JEOL JED 2300 - Nhật Bản 27 2+ Hình 2.9 Sự đổi màu dung dịch xanh của phức [Cu(NH3)4] thành nâu đỏ 2+ quá trình khử Cu thành Cu 30 2+ Hình 3.1 Phổ UV-vis của alginate (a) và phức [Cu(NH3)4] dung dịch alginate (b) 37 Hình 3.2 Ảnh TEM và phân bố kích thước hạt của nano Cu2O-Cu phụ thuộc vào nồng độ Cu 2+ 38 Hình 3.3 Ảnh TEM và phân bố kích thước hạt của nano Cu2O-Cu phụ thuộc vào nồng độ chất khử 40 Hình 3.4 Ảnh TEM và phân bớ kích thước hạt của nano Cu2O-Cu phụ thuộc vào nồng độ chất ổn định alginate 41 Hình 3.5 Phổ FT-IR của alginate và nano Cu2O-Cu/alginate 43 v Hình 3.6 Giản đờ XRD của Alginate và nano Cu2O-Cu/Alginate 40 44 Hình 3.7 Phổ EDX của chế phẩm nano Cu2O-Cu/alginate 44 2+ Hình 3.8 Phổ UV-vis của phức alginate-Cu , nano Cu2O-Cu/Alginate 45 Hình 3.9 Sơ đờ mơ mơ phản ứng tạo cấu trúc nano nhân-vỏ Cu@Cu2O 46 Hình 3.10 Sự thay đổi kích thước hạt nano Cu2O-Cu và phổ UV-vis của vật liệu theo thời gian 47 Hình 3.11 Sự phát triển của nấm Neoscytalidium dimidiatum sau ngày .51 Hình 3.12 Đờ thị tương quan giữa nồng độ Cu của nano Cu2O-Cu/alginate đến hiệu lực ức chế nấm Neoscytalidium dimidiatum 52 Hình 3.13 Triệu chứng bệnh đớm nâu dây long thí nghiệm xử ly Cu2O-Cu/alginate 55 vi MỤC LỤC Lời cam đoan i Lời cảm ơn ii DANH MỤC CÁC KÝ HIỆU VÀ CHỮ VIẾT TẮT iii DANH MỤC CÁC BẢNG iv DANH MỤC CÁC HÌNH VẼ, ĐỒ THỊ v MỤC LỤC vii MỞ ĐẦU .1 CHƯƠNG 1: TỔNG QUAN 1.1 Vật liệu nano đồng, nano oxit đồng và hiệu ứng kháng vi sinh vật gây bệnh thực vật 1.2 Rong nâu và ứng dụng của axit alginic rong nâu làm chất điêu hòa sinh trưởng thực vật và ổn định dung dịch keo nano 1.3 Bệnh đốm nâu long 1.4 Cơ chế kháng vi sinh vật của nano Cu và Cu2O 1.5 Tình hình nghiên cứu tổng hợp vật liệu nano Cu2O-Cu .11 1.6 Độc tính của nano đồng và oxit đồng 14 CHƯƠNG 2: NỘI DUNG VÀ PHƯƠNG PHÁP NGHIÊN CỨU 18 2.1 Mục tiêu nghiên cứu .18 2.2 Nội dung nghiên cứu 18 2.3 Vật liệu và phương pháp nghiên cứu 19 2.3.1 Vật liệu 19 2.3.2 Phương pháp nghiên cứu 19 2.3.2.1 Phương pháp tổng hợp nano Cu2O-Cu/alginate .19 2.3.2.2 Phương pháp chụp ảnh hiển vi điện tử truyên qua (TEM) .20 2.3.2.3 Phương pháp đo phổ nhiễu xạ tia X (XRD) 22 2.3.2.4 Phương pháp đo phổ hồng ngoại (FT-IR) 24 2.3.2.5 Phương pháp đo phổ tử ngoại – khả kiến (UV-vis) 24 2.3.2.6 Phương pháp đo phổ tán xạ lượng tia X (EDX) 26 2.3.2.7 Phương pháp xác định hàm lượng Cu nông sản phương pháp quang phổ hấp thụ nguyên tử .26 2.3.3 Phương pháp thống kê và xử ly số liệu .28 2.4 Thực nghiệm 28 2.4.1 Nghiên cứu 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synthesis and fabrication of nano Cu O on cellulosic fabric using copper sulfate and glucose in alkali media producing safe bio-and photoactive textiles without color change Cellulose, 2015, 22.6: 4049-4064 60 Judith Diaz-Visurraga, Carla Daza, Claudio Pozo, Abraham Becerra, Carlos von Plessing, Apolinaria García, Study on antibacterial alginate-stabilized copper nanoparticles by FT-IR and 2D-IR correlation spectroscopy, International Journal of Nanomedicine 7, 3597–3612, 2012 63 Cite this paper: Vietnam J Chem., 2019, 57(3), 318-323 Article DOI: 10.1002/vjch.201900022 Synthesis and in vitro antifungal efficiency of alginate-stabilized Cu 2OCu nanoparticles against Neoscytalidium dimidiatum causing brown spot disease on dragon fruit plants (Hylocereus undatus) Bui Duy Du1,2*, Doan Thi Bich Ngoc2, Nguyen Duy Thang2, Le Nghiem Anh Tuan1,2, Bui Dinh Thach3, Nguyen Quoc Hien4 Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 700000, Viet Nam Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi 100000, Viet Nam Institute of Tropical Biology, Vietnam Academy of Science and Technology, Ho Chi Minh City 700000, Viet Nam Research and Development Center for Radiation Technology, Vietnam Atomic Energy Institute, Ho Chi Minh City 700000, Viet Nam Received March 21, 2019; Accepted for publicaiton April 18, 2019 Abstract Cu2O-Cu nanoparticles (Cu2O-Cu NPs) stabilized by alginate have been developed for using as a plant fungicide The antifungal effect of Cu 2O-Cu NPs against Neoscytalidium dimidiatum fungus causing brown spot disease in dragon fruit plants was investigated Transmission electron microscopy (TEM) was used to assess the morphology and size of Cu2O-CuNPs The average diameter of spherical Cu 2O-Cu NPswas determined to be 5.40.4 nm Furthermore, the Cu2O-CuNPs stabilized in alginate were also characterized by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis Especially, the prepared Cu 2O-Cu NPs/alginate showed high antifungal efficiency (~100 %) against Neoscytalidium dimidiatum with 30 ppm concentration copper The obtained results showed that Cu 2O-Cu NPs stabilized in alginate have great potential in the development of nanomaterials for plant fungicide applications Keywords Cu2O-Cu nanoparticles, alginate, antifungal activity, Neoscytalidium dimidiatum INTRODUCTION In recent years, the researches on Cu and Cu-based nanoparticles (NPs) had drawn a lot of interests from the scientists due to their electrical and heat conductivity, magnetic, optical and catalytic properties and high anti-microorganism efficiency Cu nanomaterials are cheaper than those of Ag or Au.[1] However, Cu nanopartilces are not stable in open air due to their higher susceptibility to oxidation than bulk Cu materials, so Cu NPs were rarely applied in practice However, copper oxide (CuO, Cu2O) NPs have been widely used as a anti-microorganisms agent [2,3] Therefore, researches focused on the synthesis of Cu2O nanomaterials for applications in different industrial fields such as photovoltaic and photocatalyst[4], negative electrode for lithium-ion battery.[5] According to Wick and Tilley (2015), Cu2O NPs were a potential material in converting energy used in solar cells in low light conditions and Cu2O NPs were able to produce in large scale and cheap price.[6] In agriculture, Cu is one of the micronutrients for plant growth, which is involved in the synthesis of chlorophyll and biochemical reactions of plant cells.[1] Furthermore, Cu2O in nanosize was as highly resistant to microorganisms as that of Cu and CuO.[3,7] Recently, some researches on antifungal activity of Cu2O NPs on the plant were published, typically Huang et al (2015) used Cu 2ONPs to inhibit Alternaria solani fungus causing blight of tomato and root rot of peppers [8] Cu2O NPs had the ability to inhibit the growth of E coli bacteria If the Cu concentration increases, antifungal activity of Cu2ONPs will increase.[9-11] In Vietnam, the production of export agricultural products has beenincreased, especially high-value 318 Wiley Online Library © 2019 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co KGaA, Weinheim Vietnam Journal of Chemistry agricultural products Dragon fruit (Hylocereus undatus) has high export value that has been mainly cultivating in Binh Thuan province (30,000 ha) and Mekong delta provinces (12,000 ha) In recent years, the cultivation of dragon fruit plantsmet an obstacle by appearing brown spot disease caused by Neoscytalidium dimidiatum (N dimidiatum) Up to now, adequate fungicides for controlling this disease that causes damage to domestic and export economic have not been found.[12] The brown spot disease usually appearsin the rainy season, the infected area can be up to 90 % and the disease incidence can be 10-50 % Therefore, the study of creating new fungicides to control N dimidiatum fungi is really essential In this article, we presented the results of the synthesis of Cu2O-Cu NPs colloidal solution having high Cu concentration (5,000 ppm) from CuSO4.5H2O, hydrazine and alginate extracted from brown seaweed, Khanh Hoa province and in vitro antifungal effect of resultant Cu2O-Cu NPs/alginate on N dimidiatum causing brown spot disease in dragon fruit plants was also investigated MATERIALS AND METHODS 2.1 Materials Analytical reagents including CuSO4.5H2O, NH4OH (25 %), and N2H4.H2O (80 %) were purchased from Xilong Scientific Company Limited, China, and industrial reagent alginate (Mw ~ 51,200 g/mol) was extracted from brown seaweed at Khanh Hoa province, Vietnam The Potato Dextrose Agae (PDA) medium for fungus incubation was purchased from Himedia, India The strain of N dimidiatum was provided by the Institute of Tropical Biology VAST, Ho Chi Minh City Distilled water was used in all experiments 2.2 Synthesis of Cu2O-CuNPs/alginate colloidal solution 5.5 ml 25 % NH3 solution was added into mixture of g CuSO4.5H2O and ml water to creat Cu(NH4)42+ complex to avoid gel formation between Cu 2+ and alginate 12.5 g of alginate was dissolved in 225 ml distilled water at temperature ~ 60 oC, stirred for hours Then, the solution of Cu(NH 4)42+ complex was added into alginate solution, stirred for 10 m in order to prepare a homogeneous mixture, and then water was added to make 250 mL of solution ml of 8% hydrazine was slowly added into alginate- Bui Duy Du et al Cu2+ solution while stirring to prepare Cu2O-Cu NPs/alginate colloidal solution with 5,000 ppm Cu concentration 2.3 Characterization of Cu2O-Cu NPs/alginate Cu2O-Cu NPs/alginate powder was obtained by spray drying method The content of copper in Cu2O-Cu NPs/alginate product was determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) on a Perkin-Elmer, Optima 5300 DV The functional groups of the Cu 2O-Cu NPs/alginate were analyzed by FT-IR technique Spectral-grade KBr powder was mixed with Cu 2OCu NPs/alginate at a weight ratio of mg Cu 2O-Cu NPs/alginate: 200 mg KBr in an agate mortar The mixture powder was pressed into pellets with a diameter of 13 mm and thickness of 0.5 mm The infrared (IR) spectrum of Cu2O-Cu NPs/alginate was measured by using FT-IR spectroscopy (FT-IR 8400S, Shimadzu) over the wavenumber range from 4000 to 400 cm-1 X-ray diffraction (XRD) of Cu2OCu NPs/alginate product was carried out on D8 Advance Bruker, Germany The XRD pattern was obtained by using CuKα as a radiation source (λ = 1.5405 Å) operating under a constant current of 30 mA at 40 kV with a diffraction angle (2θ) scan range from to 80° And the Cu2O-CuNPs size was measured using a transmission electron microscope (TEM; JEM 1010, JEOL, Tokyo, Japan) 2.4 In vitro antifungal effect of Cu2OCuNPs/alginate against N dimidiatum fungus The antifungal activity of Cu2O-Cu NPs/alginate was tested against N dimidiatumby culture medium toxicity method.[13,14] Firstly, PDA culture medium was prepared For investigation of the concentration effect, Cu2O-Cu NPs/alginatewith concentration of (control), 15.0; 22.5 and 30.0 ppm Cu were added to potato dextrose agar (PDA) media Secondly, N dimidiatum fungi colonies were given directly into the center of agar surface The PDA agar plate containing the both fungi colonies and test samples or the control were incubated at 30 oC Each experiment was performed in triplicates After days incubation, the antifungal effect was evaluated by measuring diameter of colony growth and calculated as follows: Inhibition efficiency (%) = 100d/d0 where: d0 and d are the fungal growth diameter (mm) of the control and studied samples, respectively © 2019 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co KGaA, Weinheim www.vjc.wiley-vch.de Vietnam Journal of Chemistry 2.5 Statistical Analysis 319 Cu2O-CuNPs size was statistically calculated from TEM image by Photoshop CS6 and Microsoft EXCEL 2010 software All data were expressed as mean ± standard error (SE) and subjected to statistical analysis with the JMP Statistical Discovery v10.0 software (SAS Institute Inc., USA) One-way ANOVA was performed for each treatment including three replicates Significant differences between means were determined by Ducan’s multiple range test at P < 0.05 RESULTS AND DISCUSSION 3.1 Synthesis and characterization of Cu 2O-Cu NPs/alginate Hydrazine hydrate (N2H4.H2O) and NH3·H2O were used as reductant and buffer agent, respectively [15] The optimum reduction of Cu2+ can be achieved at Synthesis and in vitro antifungal efficiency of… pH > 11.[16] The color of Cu2+solution was blue before being reduced, and became yellow after reduction In this process, the following chemical reactions occurred: Cu2+ +4NH3 → [Cu(NH3)4]2+ 2[Cu(NH3)4]2+ + N2H4 + 5OH- + alginate Cu2O/alginate + N2+ 4NH3 + 4NH4+ + 4H2O (Cu2O + Cu2O + Cu2O + ⋅⋅⋅)/alginate → Cu2O NPs/alginate In aqueous ammonia media, ammonia reacts with Cu2+ according to the reaction (1) and [Cu(NH3)4]2+ complex was created to avoid Cu 2+ to form complexes with alginate as being seen in Equation (2) Then the cuprous ions react with hydroxyl in the system to form cuprous oxide [17] The copper ions Cu2+ may be reduced to cuprous ions according to the reaction (4) Cuprous oxide may be produced via oxidation of Cu as the reaction (5): 2Cu2++ N2H4+ 4OH−+ alginate → 2Cuo/alginate + N2+ 4H2O a) Frequency, % Cuo/alginate + O2 → Cu2O/alginate b) Average diameter = 5.4±0.4 nm Diameter, nm Figure 1: TEM image (a) and particle size distribution (b) of Cu2O-Cu NPs/alginate The morphology and size of Cu 2O-Cu NPs/alginate are shown in figure Cu2O-Cu NPshad spherical shape, good separation, small particle size and distribution in narrow ranges mainly from 3-7 nm Particularly, the average size of Cu2O-Cu NPs was were 5.4±0.4 nm It was observed from TEM image that alginate enables better the dispersion of Cu2O-Cu NPs and seemed to be suitable as a stabilizer in synthesis of Cu2O-CuNPs colloidal solution The content of Cu in Cu2O-Cu NPs/alginate colloidal solution was determined by ICP-AES method is 5.06 ppm IR spectra data of alginate and Cu2O-Cu NPs/alginate are shown in figure Figure 2a showed that a wide band at 3469 cm -1 and a weak band at 2931 cm-1 were assigned to hydrogen bonded (O–H) and (C–H) stretching vibrations, respectively Two strong absorptions were observed at 1610 cm-1and 1415 cm-1 They were attributed to asymmetric and symmetric stretching vibrations of carboxylate groups (O–C–O).[18] According to Fenoradosoa et al (2010), the absorption at 1415 cm−1 was assigned to C–OH deformation vibration with contribution of O–C–O symmetric stretching vibration of carboxylate group.[19] The one band at 1128 cm-1 was assigned to C–O stretching for © 2019 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co KGaA, Weinheim www.vjc.wiley-vch.de Vietnam Journal of Chemistry 320 pyranose Figure 2b showed a shift from 3469 to 3438 cm−1 is observed for stabilized Cu2O-Cu NPs; this decrease in frequency may occur due to the interaction of Cuo with –OH groups.[20] Furthermore, the characteristic band centered at 618.46 cm –1 for Cu2O was ascribed to the vibrational mode of Cu–O a) Bui Duy Du et al in Cu2O phase.[21] When stabilization occurs, the band corresponding to –C–O– stretching appear shifted at lower frequency (1128 to 1111 cm −1).[20] Therefore, the obtained results of IR spectra confirmed the formation of Cu2O NPs b) Figure 2: FT-IR spectra of brown seaweed alginate (a) and Cu 2O-Cu NPs/alginate (b) a) b) Figure 3: XRD patterns of brown seaweed alginate (a) and Cu2O-Cu NPs/alginate (b) XRD patterns of brown seaweed alginate and Cu2O-Cu NPs/alginate are shown in figure Figure 3a showed that alginate extracted from brown seaweed (Khanh Hoa province) appeared characteristic peaks at 2θ ~13.6 o and 21.5o,[18] there were also peaks at 2θ ~28.2 o; 29.3o; 31.9o; 32.4o and 34.2o, which proved that alginate extraction has crystalline structure, which contains other impurities in brown seaweed that were inorganic or organic compounds Because alginate extracted from brown seaweed was subjected to agricultural application, so in the extraction process we did not remove mineral salts and organic compounds, these compounds had the effect of regulating growth for crops Figure 3b showed the XRD pattern of Cu2O-Cu NPs/alginate The diffraction pattern exhibited the characteristic peaks of two phases; crystalline metallic copper (cubic) and Cu2O (cubic) This means that Cu2+ ions were already reduced to Cu and Cu + The XRD pattern of Cu2O showed the peaks corresponding to ~29.6o (1 0); 36.5o (1 1); 42.4o (2 0); 61.5o (2 0); 73.6o (3 1); 77.5o (2 2) The XRD pattern showed the peaks for Cu at 2θ ~ 43.4 o (1 1); 50.4o (2 0); 74.5o (2 0) All peaks can be attributed to the cubic form of metallic copper [22] These peaks are very close to that given by JCPDS data of XRD for Cu2O (JCPDS: 34-1354) and Cu (JCPDS: 040836) The results of this study were also consistent with the studies of Badawy[22] and Maximino.[23] 3.2 Antifungal activity of Cu2O-Cu NPs/alginate The antifungal effect of Cu2O-Cu NPs/alginate increased with the Cu concentration After incubation for days, the growth inhibition was of 25.1 %, 61.1 %, and 100 % for Cu 15.0, 22.5 and 30 © 2019 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co KGaA, Weinheim www.vjc.wiley-vch.de 321 Vietnam Journal of Chemistry ppm, respectively Results in Figure indicated that the antifungal efficiency increased strongly when concentration of Cu increased After days of incubation, N dimidiatum fungal growth normally on the control plates with the diameter reached 90 mm However, cultural media supplemented with Cu at 22.5 ppm showed strong inhibition effects on N dimidiatum with the fungal diameter only reached 55 mm (61.1 % inhibition) The antifungal efficiency increased to ~100 % at Cu concentartion of 30 ppm Based on the results in figure 4, ED50 (effective dose Synthesis and in vitro antifungal efficiency of… for 50 % inhibition) of Cu on N dimidiatum was found to be 20.8 ppm The antifungal effect of AgNPs/chitosan on N dimidiatum in the dragon fruit plants was also investigated by Phan Ngoc et al (2018) with highest inhibitory effect at 10 ppm Ag and 2% chitosan.[24] In addition, Du et al (2015) reported that oligochitosan against N dimidiatum with EC50 = 51.5 ppm.[14] Beside, nSiO2-OC also showed high efficiency in controlling brown spot disease on dragon fruit plants caused by N dimidiatum fungal.[25] Figure 4: The antifungal effect of Cu2O-Cu NPs/alginate on N dimidiatum after days of incubation CONCLUSION In this study, we have prepared the Cu2O-Cu NPs/alginate colloidal solution with high concentration of 5,000 ppm Cu, the average particle size of 5.4±0.4 nm, the particle size distribution in a narrow range The Cu2O-Cu NPs/alginate product exhibited highly antifungal efficiency (~100 %), for the growth of N dimidiatum causing brown spot disease on dragon fruit plant at 30.0 ppm Cu concentration The results of this study revealed that Cu 2O-Cu NPs/alginate is a potential material used as a fungicide in sustanable agriculture production Acknowledgments This research is funded by Science and Technology Programme for the Sustainable Development of the Mekong Delta Region under grant number TNB.ĐT/14-19/C38 Dhanasekaran, N Thajuddin and A Panneerselvam), published by Intech, Rijecka, Croatia, 257-278, 2012 L Xiong, Z.-H Tong, J.-J Chen, L.-L Li, H.-Q Yu Morphology-dependent antimicrobial activity of Cu/Cu O nanoparticles, Ecotoxicology, 2015, 24 (10), 2067-2072 K Giannousi, G Sarafidis, S Mourdikoudis, A Pantazaki, C Dendrinou-Samara Selective synthesis of Cu2O and Cu/Cu2O NPs: antifungal activity to yeast saccharomyces cerevisiae and DNA interaction, Inorg Chem., 2014, 53(18), 9657-9666 N Gu, J Gao, H Li, Y Wu, Y Ma, K Wang Montmorillonite-supported with Cu2O 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Hien Synthesis and investigation of antimicrobial activity of Cu2O nanoparticles/zeolite, J Nanoparticles, 2017, Article ID 7056864, 1-6 12 L H Thanh, N K B Tam, V T Nga, H T Thuy, T V Hai, H T Son, N N Quynh, N T H Nga Study on the possibility of using microorganisms as biological agents to control fungal pathogens Neoscytalidium dimidiatum causing disease of brown spots on the dragon fruit, J Viet Env., 2016, 8(1), 4144 13 D V Phu, V T K Lang, N T K Lan, Ng N Duy, N D Chau, B D Du, B D Cam, N Q Hien Synthesis and antimicrobial effects of colloidal silver nanoparticles in chitosan by γ-irradiation, J Exp Nanosci., 2010, 5(2), 169-179 14 B D Du, L T K Dung, V N D Khoa, N D Thang, L N A Tuan Chitinase-induced resistance against Neoscytalidium dimidiatum on dragon trees: the effect of oligochitosan prepared by the heterogeneous degradation of chitosan with H2O2 under hydrothermal conditions, Vietnam J Chem., 2015, 53(2), 161-165 15 W.Songping, M Shuyuan Preparation of micron size copper powder with chemical reduction method, Mater Lett., 2006, 60, 2438-2442 16 J P Chen, L L Lim Key factors in chemical reduction by hydrazine for recovery of precious metals,Chemosphere, 2002, 49, 363-370 Corresponding author: Bui Duy Du Institute of Applied Materials Science Vietnam Academy of Science and Technology 1A TL29 Str., Thanh Loc ward District 12, Ho Chi Minh City 700000, Viet Nam E-mail: vina9802@gmail.com © 2019 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co KGaA, Weinheim www.vjc.wiley-vch.de 323 ... DỤC VÀ ĐÀO TẠO HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ - Nguyễn Duy Thắng TỔNG HỢP NANO CU2 O- CU/ ALGINATE VÀ KHẢO SÁT KHẢ NĂNG KHÁNG NẤM NEOSCYTALIDIUM DIMIDIATUM GÂY BỆNH ĐỐM NÂU TRÊN CÂY... nghiệm 1: Khảo sát kích thước hạt Cu2 O- Cu (TEM) ổn định polyme alginate phụ thuộc vào nồng độ Cu2 + quy trình điều chế nano Cu2 O- Cu/ alginate − Thí nghiệm 2: Khảo sát kích thước hạt Cu2 O- Cu (TEM)... cu? ?a Alginate và nano Cu2 O- Cu/ Alginate 40 44 Hình 3.7 Phổ EDX cu? ?a chế phẩm nano Cu2 O- Cu/ alginate 44 2+ Hình 3.8 Phổ UV-vis cu? ?a phức alginate -Cu , nano Cu2 O- Cu/ Alginate 45 Hình