With the rapid development of biotechnology and nanomedicine, extensive research has focused on the investigations of delivering large-cargo molecules using nanoparticles through the cell membrane for disease diagnosis and treatment. Various inorganic and polymeric nanoparticles with optimized surface properties have been developed to carry these active cargo molecules such as organic molecules, oligonucleotides and proteins. Phagocytosis and pinocytosis have been suggested as the two major uptake mechanisms for nanoparticles to enter into cellular interior, but such mechanisms are still under debate. In order to enhance the efficiency of cellular uptake of nanoparticles and further understand the physiological process, it is important to investigate detailed interaction mechanisms between nanoparticles and cell membranes. Here, we will review the recent advances of the effect of nanoparticle properties (e.g., nanoparticle shape, size, charge, surface modification, etc.) on cellular uptake mechanisms. These will aid in the future design and development of nanoparticles with improved surface properties for drug and biomolecule delivery. Up to now, novel analytical techniques have been used to examine nanoparticle-cell membrane interactions, but their detailed uptake mechanisms and pathways still need more in-depth research. It is suggested that developing appropriate analytical techniques to study cellular uptake mechanisms of nanoparticles in real time is urgently desired.
Core-shell structured silica/magnetic nanoparticle composites have recently been subjected to extensive research since the shells could offer protection to the cores and introduce new properties to the hybrid structures, which endue them with great application potentials in various fields. Several approaches have been studied for the synthesis of SiO2 coated on magnetic nanoparticles. These approaches include Stöber process, microemulsion, sodium silicate and tetraethoxysilane hydrolysis, aerosol pyrolysis, layer-by-layer strategy, polymer-templating and sonochemical deposition. This review is focused on describing state-of-the-art synthetic routes and methods for the preparation of silica/magnetic nanoparticle composites. Furthermore, we also introduce main applications of these nanoparticle composites in biomedical scopes and address some challenges in the synthesis of high-quality magnetic nanoparticles.
Hepatitis B virus is a kind of DNA virus which can cause serious epidemic disease. The analysis and detection of sequence-specific DNA have great significance in forensic analysis, early-stage identification and treatment of genetic disorders. Chemiluminescent detection of DNA has been applied in many fields, such as biological technology and molecular biology, due to its simple operation and high sensitivity. On the other hand, owing to possessing easy magnetic separation and large surface properties, magnetic nanoparticles have also been employed as special carriers to immobilize biomolecules. In this paper, the magnetic nanoparticles are prepared by soft-template method with uniform shape and good dispersion. Then a detection method of hepatitis B virus DNA is established taking advantages of both chemilumiescence with the system of alkaline phosphatase catalyzing 3-(2 -spiroadamantane)-4-methoxy -4-(3 -phosphoryloxy) phenyl-1, 2-dioxetane and magnetic nanoparticles. The optimization of conditions affecting the hybridization reaction and the chemilumiescence detection are also investigated to promise a high sensitivity.
A rapid detection method of Pseudomonas aeruginosa based on magnetic separation and chemiluminescence was developed in this paper. Magnetic nanoparticles (MNPs) were prepared by solvothermal method with PEG-4000 as a surfactant, and then were modified. The prepared MNPs present a uniform morphology and good dispersion. The sizes of MNPs can be controlled by adjusting the dosage of FeCl3 x 6H2O. The obtained particles were characterized with Scanning electron microscope (SEM), Transmission electronic microscopy (TEM) and Fourier transform infrared (FTIR). The biotin-dUTP-labeled DNA fragments of gyrB gene were amplified by polymerase chain reaction (PCR), and Pseudomonas aeruginosa was successfully detected with detection limit as low as 7.5 fM of gyrB fragments.
Molecular detection of HBV has a significant impact on prognosis and therapy of the disease. In this paper, a sensitive nucleic acid detection method of HBV was established taking advantage of magnetic nanoparticles (MNPs), chemiluminescence (CL) and polymerase chain reaction (PCR). HBV-DNA was extracted from hepatitis B positive human blood samples using MNPs adsorption method and biotin was labeled on the DNA segment after base insertion of bintin-dUTP in PCR. The biotinylated DNA segment was captured by amino probe immobilized on carboxyl MNPs and was detected by the chemiluminescence system of alkaline phosphatase catalyzing 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy) phenyl-1, 2-dioxetane. Different concentrations of HBV-DNA were detected under the optimized experiment conditions and the relevant CL intensity were obtained, which provided a novel research or clinic diagnosis method for the quantification detection of HBV-DNA.
In many molecule biology and genetic technology studies, the amount of available DNA can be one of the important criteria for selecting the samples from different sources. Compared with those genomic DNA methods using organic solvents or other traditional commercial kits, the method based on magnetic nanoparticles (MNPs) and adsorption technology has many remarkable advantages like being time-saving and cost effective without the laborious centrifugation or precipitation steps, and more importantly it has the great potential and especially suitable for automated DNA extraction and up-scaling. In this paper, the extraction efficiency of genomic nucleic acids based on magnetic nanoparticles from four different sources including bacteria, yeast, human blood and virus samples are compared and verified. After measurement and verification of the extracted genomic nucleic acids, it was shown that all these genomic nucleic acids extracted using the MNPs method can be of high yield and be available for next molecule biological steps.
In present study, we put forward an approach to prepare three-layer core-shell Fe3O4@SiO2@Au magnetic nanocomposites via the combination of self-assembling, seed-mediated growing and multi-step chemical reduction. The Fe3O4@SiO2@Au magnetic nanocomposites were analyzed and characterized by transmission electron microscope (TEM), scanning electronic microscope (SEM), energy dispersive spectrometer analysis (EDS), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), and ultraviolet and visible spectrophotometer (UV-Vis). TEM and SEM characterizations showed that the FeO4@SiO2@Au nanocomposites were obtained successfully with three-layer structures, especially a layer of thin, smooth and continuous gold shell. The average diameter of Fe3O4@SiO2@Au nanocomposites was about 600 nm and an excellent dispersity was observed for the as-prepared nanoparticles. EDS characterizations demonstrated that the nanocomposites contained three elements of the precursors, Fe, Si, and Au. Furthermore, FT-IR showed that the silica and gold shell were coated successfully. UV-Vis and VSM characterizations showed that the Fe3O4@SiO2@Au nanocomposites exhibited good optical and magnetic property, and the saturation magnetization was 25.76 emu/g. In conclusion, the Fe3O4@SiO2@Au magnetic nanocomposites with three-layer core-shell structures were prepared. Furthermore, Fe3O4@SiO2@Au magnetic nanocomposites were modified with streptavidin (SA) successfully, and it was validated that they performed low fluorescence background, suggesting that they should have good applications especially in bioassay based on fluorescence detection through bonding the biotinylated fluorescent probes.
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