Mussel-Inspired Polydopamine Coated Iron Oxide Nanoparticles for Biomedical Application

Mussel-inspired polydopamine (PDA) coated iron oxide nanoparticles have served as a feasible, robust, and functional platform for various biomedical applications. However, there is scarcely a systemic paper reviewed about such functionalising nanomaterials to date. In this review, the synthesis of iron oxide nanoparticles, the mechanism of dopamine self-oxidation, the interaction between iron oxide and dopamine, and the functionality and the safety assessment of dopamine modified iron oxide nanoparticles as well as the biomedical application of such nanoparticles are discussed. To enlighten the future research, the opportunities and the limitations of functionalising iron oxide nanoparticles coated with PDA are also analyzed

Synthesis of Superparamagnetic Iron Oxide Nanoparticles Modified with MPEG-PEI via Photochemistry as New MRI Contrast Agent

Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) coated with polyethylenimine (PEI) and modified with poly(ethylene glycol) methyl ether (MPEG), MPEG-PEI-SPIONs, was developed. PEI-SPIONs were successfully prepared in aqueous system via photochemistry, and their surface was modified with poly(ethylene glycol) methyl ether (MPEG). The so-obtained MPEG-PEI-SPIONs had a uniform hydrodynamic particle size of 34 nm. The successful coating of MPEG-PEI on the SPIONs was ascertained from FT-IR analysis, and the PEI and MPEG fractions in MPEG-PEI-SPIONs were calculated to account for 31% and 12%, respectively. Magnetic measurement revealed that the saturated magnetization of MPEG-PEI-SPIONs reached 46 emu/g and the nanoparticles showed the characteristic of being superparamagnetic. The stability experiment revealed that the MPEG-PEI modification improved the nanoparticles stability greatly. T2 relaxation measurements showed that MPEG-PEI-SPIONs show similar R2 value to the PEI-SPIONs. The T2-weighted magnetic resonance imaging (MRI) of MPEG-PEI-SPIONs showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticle concentration in water. These results indicated that the MPEG-PEI-SPIONs had great potential for application in MRI

Highly Selective Electrochemical Strategy for Monitoring of Cerebral Cu²⁺ Based on a Carbon Dot-TPEA Hybridized Surface

Direct determination of cerebral metal ions in small volume biological samples is still the bottleneck for evaluating the roles that metal ions play in the physiological and pathological processes. In this work, selected copper ion (Cu²⁺) as a model, a facile and direct electrochemical method for detection of Cu²⁺ has been developed on the basis of two new designed strategies: one is specific recognition molecule for Cu²⁺-AE-TPEA (N-(2-aminoethyl)-N,N′,N′-tris­(pyridine-2-yl-methyl)­ethane-1,2-diamine); another is carbon dots (C-Dots) with high electrocatalytic activity. Based on the high affinity between TPEA and Cu²⁺, the electrode assembled with C-Dot-TPEA hybridized nanocomposites shows high selectivity toward Cu²⁺ over other metal ions, amino acids, and biological coexisting species, such as uric acid (UA), ascorbic acid (AA), and so on, which makes it possible to be used for determination of Cu²⁺ in the complex brain system. By taking advantage of C-Dots, a dynamic linear range from 1 μM to 60 μM is first achieved with a detection limit of ∼100 nM in aCSF solution. In addition, the developed method with theoretical simplicity and less instrumental demands exhibits long-term stability and good reproducibility. As a result, the present strategy has been successfully applied in detection of cerebral Cu²⁺ in normal rat brain and that followed by global cerebral ischemia, combined with in vivo microdialysis. The determined concentrations of Cu²⁺ in the rat brain microdialysates by the present method are found to be identical to those obtained by the conventional ICP-AES method

Six2 Is a Coordinator of LiCl-Induced Cell Proliferation and Apoptosis

The metanephric mesenchyme (MM) cells are a subset of kidney progenitor cells and play an essential role in mesenchymal-epithelial transition (MET), the key step of nephron generation. Six2, a biological marker related to Wnt signaling pathway, promotes the proliferation, inhibits the apoptosis and maintains the un-differentiation of MM cells. Besides, LiCl is an activator of Wnt signaling pathway. However, the role of LiCl in cellular regulation of MM cells remains unclear, and the relationship between LiCl and Six2 in this process is also little known. Here, we performed EdU assay and flow cytometry assay to, respectively, detect the proliferation and apoptosis of MM cells treated with LiCl of increasing dosages. In addition, reverse transcription-PCR (RT-PCR) and Western-blot were conducted to measure the expression of Six2 and some maker genes of Wnt and bone-morphogenetic-protein (BMP) signaling pathway. Furthermore, luciferase assay was also carried out to detect the transcriptional regulation of Six2. Then we found LiCl promoted MM cell proliferation at low-concentration (10, 20, 30, and 40 mM). The expression of Six2 was dose-dependently increased in low-concentration (10, 20, 30, and 40 mM) at both mRNA and protein level. In addition, both of cell proliferation and Six2 expression in MM cells declined when dosage reached high-concentration (50 mM). However, Six2 knock-down converted the proliferation reduction at 50 mM. Furthermore, Six2 deficiency increased the apoptosis of MM cells, compared with negative control cells at relative LiCl concentration. However, the abnormal rise of apoptosis at 30 mM of LiCl concentration implies that it might be the reduction of GSK3β that increased cell apoptosis. Together, these demonstrate that LiCl can induce the proliferation and apoptosis of MM cells coordinating with Six2