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.

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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.