Nucleotide incorporated magnetic microparticles for isolation of DNA

Enhanced sensitivity and efficiency of detection of Staphylococcus aureus based on modified magnetic nanoparticles by photometric systems

Staphylococcus aureus is an important infectious factor in the food industry and hospital infections. Many methods are used for detecting bacteria but they are mostly time-consuming, poorly sensitive. In this study, a nano-biosensor based on iron nanoparticles (MNPs) was designed to detect S. aureus. MNPs were synthesized and conjugated to Biosensors. Then S. aureus was lysed and nano-biosensor (MNP-TiO₂-AP-SMCC-Biosensors) was added to the lysed bacteria. After bonding the bacterial genome to the nano-biosensor, MNPs were separated by a magnet. Bacterial DNA was released from the surface of nano-biosensor and researched by Nano-drop spectrophotometry. The results of SEM and DLS revealed that the size of MNPs was 20-25 nm which increased to 38-43 nm after modification and addition of biosensors. The designed nano-biosensor was highly sensitive and specific for the detection of S. aureus. The limit of detection (LOD) was determined as 230 CFU mL^-1. There was an acceptable linear correlation between bacterial concentration and absorption at 3.7 × 10²-3.7× 10⁷ whose linear diagram and regression was Y = 0.242X + 2.08 and R² = .996. Further, in the presence of other bacteria as a negative control, it was absolutely specific. The sensitivity of the designed nano-biosensor was investigated and compared through PCR.

Functionalization of anti-Brucella antibody based on SNP and MNP nanoparticles for visual and spectrophotometric detection of Brucella

An Immuno-Nano-Biosensor with high sensitivity was designed based on iron and silica nanoparticles to detect B. abortus. Briefly explain, primary polyclonal antibody (IgG₁) was conjugated on surface magnetic nanoparticles (MNPs) to form MNP-IgG₁. Secondary polyclonal antibody (IgG₂) and Horseradish Peroxidase enzyme were conjugated on silica nanoparticles (SNPs) to form HRP-SNP-IgG₂. HRP-SNP-IgG₂. MNP-IgG₁ and HRP-SNP-IgG₂ were added to B. abortus. The MNP-IgG₁-B.abortus-IgG₂-SNP-HRP complex was isolated from the reaction mixture using a magnet. After that, tetramethylbenzidine was added to the complex. The reaction was stopped with HCl and investigated using UV-Vis spectrophotometry. The nanoparticles' structure and size were investigated using SEM and DLS. Immuno-Nano-Biosensor sensitivity and specificity were determined. The SEM and DLS results indicated that the SNPs, MNPs, HRP-SNP-IgG₂ and MNP-IgG₁ size and structure were 35, 44, 60 and 56 nm, respectively. In addition, a good linear correlation was observed at 10²-10⁷ CFU mL^-1 concentrations, which their linear equation and regression were Y = 0.3× + 0.18 and R² 0.982, respectively. The limitation of detecting B. abortus was 160 CFU mL^-1. Finally, the results demonstrated that those designed Immuno-Nano-Biosensor could be specifically detected B. abortus and B. melitensis in real samples.

Magnetic diatomite for pesticide removal from aqueous solution via hydrophobic interactions

Pesticides are highly hazardous chemicals for the environment and human health and their use in agriculture is constantly increasing. Although 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane 4,4'-DDT was banned at developed countries, it is still one of the most dangerous of chemical due to accumulation in the environment. It is known that the toxicity of DDT affects some enzyme systems biochemically. The main motivation of this study is to develop an effective adsorbate for the removal DDT, which was chosen as a model hydrophobic pesticide, out of aqueous systems. For this purpose, the bare diatomite particles were magnetically modified and a hydrophobic ligand attached to enhance its adsorptive and physio-chemical features. Under optimal conditions, a high adsorption capacity, around 120 mg/g with the hydrophobic and magnetic diatomite particles, modification of the diatomite particles reduced average pores diameter whereas surface area and total pore volume increased (around 15-folds). After five consecutive adsorption-desorption cycles, no significant decrease in adsorption capability was observed. The adsorption isotherms (Langmuir, Freundlich, and Flory-Huggins) applied to the data indicated that the adsorption process occurred via monolayer adsorption in an entropy-driven manner. The kinetic data also revealed the quick adsorption process without any diffusion limitations. Graphical Abstract.

Extraction of DNA from complex biological sample matrices using guanidinium ionic liquid modified magnetic nanocomposites

A series of guanidinium ionic liquid modified magnetic chitosan/graphene oxide (GIL-MCGO) nanocomposites have been prepared for DNA extraction via magnetic solid-phase extraction technology. These nanocomposites are of only 20 nanometers in diameter. Single stranded DNA or DNA sodium salts that were absorbed by GIL-MCGO could be quickly collected by an external magnet and extracted. The DNA extraction efficiency of 11 GIL-MCGO nanocomposites was evaluated using NanoDrop. Factors that could impact the DNA extraction process, such as pH, temperature, extraction time, and ionic strength were systematically investigated via single-factor experimental analysis. Under the optimum extraction conditions, a maximum DNA extraction capacity of 233.0 ± 0.4 mg g⁻¹ of GIL-MCGO nanocomposite was achieved. The solid phase extraction method based on GIL-MCGO nanocomposites has been demonstrated with the extraction of DNA from a series of complex sample matrices, including single stranded DNA samples, salmon sperm DNA sodium salt, human whole blood and E. coli cell lysate. The DNA extracted by using the GIL-MCGO nanocomposites are well suitable for PCR amplifications. In addition, an initial study on the interaction between GIL-MCGO and DNA was conducted: the preference of GIL-MCGO on DNA absorption with varying base composition was tested. Only a slight loss in the DNA extraction efficiency of GIL-MCGO was observed after four extraction–desorption cycles, proving excellent regeneration performance and recyclability of the GIL-MCGO nanocomposites in the DNA extraction process.

The DNA extracted from biological samples by using the GIL-MCGO nanocomposites are well suitable for PCR amplifications.

Removal of DDE by exploiting the alcoho-phobic interactions

DDE (1,1-bis-(4-chlorophenyl)-2,2-dichloroethene), which is a commonly used pesticides in agriculture, has harmful effects on human health. Therefore, the removal of this substance from the drinking water and the soil is essential. Since DDT (1,1″-(2,2,2-Trichloroethane-1,1-diyl) bis(4-chlorobenzene)) is derivation of DDE, the presence of DDT can be monitored by the detection of DDE present in the environment. Herein, we report on the development of aspartic acid-incorporated poly(2-hydroxyethyl methacrylate-L-aspartic acid) [poly(HEMA-MAsp)] cryogel for the removal of DDE from aqueous solutions for the first time in the literature. The synthesized cryogels were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), an N₂ adsorption method, elemental analysis, and swelling test. The separation experiments were carried out via a batch system to get the optimum adsorption conditions including pH, interaction time, initial DDE concentration, and temperature. The desorption and the reusability results revealed that there was no significant decrease in the DDE adsorption capacity of the cryogels after five adsorption-desorption cycles. The maximum DDE adsorption capacity of poly(HEMA-MAsp) cryogels was found to be 31.51 mg DDE/g polymer for 50 mg DDE/L solution.