scholarly journals Antibacterial activity of ZnO nanoparticles: dependence on particle size, dispersion media and storage time

Author(s):  
O Zakharova ◽  
E Kolesnikov ◽  
E Vishnyakova ◽  
N Strekalova ◽  
A Gusev
2021 ◽  
Author(s):  
Reza Eivazzadeh-Keihan ◽  
Ensiye Zare-Bakheir ◽  
Hooman Aghamirza Moghim Aliabadi ◽  
Mostafa Ghafori Gorab ◽  
Hossein Ghafuri ◽  
...  

Abstract In this study, a novel nanobiocomposite was synthesized using graphene oxide, lignin, silk fibroin and ZnO and used in biological fields. To synthesize this structure, after preparing graphene oxide by the Hummer method, lignin, silk fibroin, and ZnO nanoparticles (NPs) were added to it, respectively. Also, ZnO NPs with a particle size of about 18 nm to 33 nm was synthesized via Camellia sinensis extract by green methodology. The synthesized structure was examined as anti-biofilm agent and it was observed that the Graphene oxide-lignin/silk fibroin/ZnO nanobiocomposite has a significant ability to prevent the formation of P. aeruginosa biofilm. In addition, due to the importance of the possibility of using this structure in biological environments, its toxicity and blood compatibility were also evaluated. According to the obtained results from MTT assay, the viability percentages of Hu02 cells treated with Graphene oxide-lignin/silk fibroin/ZnO nanobiocomposite after 24, 48, and 72 h of incubation were 89.96%, 89.32%, and 91.28%. On the other hand, the hemolysis percentage of the synthesized structure after 24 h and 72 h of extraction was 9.5% and 11.76% respectively. As a result, the synthesized structure is hemocompatible and had no toxic effects on Hu02 cells.


2014 ◽  
Vol 34 (03) ◽  
pp. 330 ◽  
Author(s):  
Dharia Renate ◽  
Filli Pratama ◽  
Kiki Yuliati ◽  
Gatot Priyanto

The objective of this research was to asses relationship between temperature and storage time of capsaicin degradation of red chilli paste and to measure activation energy and shelf life using the Arrhenius model. The treatmens were storage temperature (20°C, 30°C, 40°C) and storage times (0, 2, 4, 6, 8, 10 weeks).  Parameters analyzed were capsaicin content using HPLC method, pH, and particle size.  The data was analyzed using linier regression and Arrhenius equation  The results showed that temperature condition and storage time affected capsaicin degradation of red chilli paste, unlike pH and particle size.  The longer storage time the lower capsaicin content.  The capsaicin content of red chilli paste storedat 30°C and 40°C in week-4 was 746,36 μg/g and 714,19 μg/g respectively, and it declined to 149,31 μg/g and 136,77 μg/g after being stored for ten weeks.  Research concluded that red chilli paste stored for 10 weeks at 20°C caused the lowest capsaicin degradation from   916.8029 μg/g  to 683.8097 μg/g. Degradation rate of capsaicin followed the first order reaction.  Arrhenius equation for capsaicin was  Y= -9356.3x + 27.836, (R=0.76), and activation energy was 18.581 kcal/mol.  Shelf life determination of capsaicin followed kinetic reaction equation of the fi rst order  i.e t = ln(Ao-At)/k.  The self life of red chilli paste stored at 20°C, 30°C and 40°C were 10.62 weeks, 8.62 weeks and 8.45 weeks respectively.Keywords: Red chilli paste, degradation, capsaicin, particle size, kinetic reaction ABSTRAKTujuan penelitian untuk mengkaji hubungan suhu dan lama penyimpanan terhadap degradasi capsaicin cabai merah giling serta menghitung energi aktivasi dan waktu simpan dengan pendekatan model persamaan Arrhenius. Perlakuan terdiri dari dua faktor yaitu suhu penyimpanan (20°C, 30°C, dan 40°C) serta lama penyimpanan (0, 2, 4, 6, 8 dan 10minggu). Metode analisis untuk kadar capsaicin menggunakan HPLC. Analisis pendukung yaitu pH dan ukuran partikel.  Data disajikan dengan grafi k persamaan regresi linier dan persamaan Arrhenius.  Hasil penelitian menunjukkan bahwa kondisi suhu dan lama penyimpanan berpengaruh terhadap degradasi capsaicin cabai merah giling, namun, pH dan ukuran partikel tidak berpengaruh secara signifi kan.  Semakin lama penyimpanan maka kandungan capsaicin semakin menurun.  Kadar capsaicin cabai giling yang disimpan pada suhu 30°C dan 40°C  pada minggu ke-empat masing masing sebesar 746,36 μg/g dan 714,19 μg/g menurun perlahan sampai pada  minggu ke-10 menjadi 149,31 μg/g dan 136,77 μg/g.  Dari hasil penelitian disimpulkan bahwa kadar capsaicin cabai giling yang disimpan pada suhu 20°C selama 10 minggu merupakan degradasi terendah dari 916,80 μg/g menjadi 683,81 μg/g.  Laju degradasi capsaicin mengikuti orde satu.  Persamaan Arrhenius untuk Capsaicin adalah Y= 27,836-9356,3x (R=0,76) dan energi aktivasisebesar 18581,65 kal/mol. Penentuan umur simpan capsaicin mengikuti persamaan kinetika reaksi orde satu yaitu t =ln(Ao-At)/k, maka umur simpan capsaicin cabai merah giling yang disimpan pada suhu 20°C, 30°C dan 40°C berturutturut sebesar 10,64 minggu; 8,62 minggu dan 8,45 minggu.Kata kunci: Cabai merah giling, degradasi, capsaicin, ukuran partikel, kinetika reaksi


Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2339
Author(s):  
So-Yul Yun ◽  
Jee-Young Imm

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks’ storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation.


2021 ◽  
pp. 111115
Author(s):  
Steplinpaulselvin Selvinsimpson ◽  
Gnanamozhi P ◽  
Pandiyan V ◽  
Mani Govindasamy ◽  
Mohamed A. Habila ◽  
...  

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