Superparamagnetic nanoparticles with superhigh T2 relaxivity and cellular uptake are strongly desired for ultrasensitive magnetic resonance imaging (MRI). Towards this end, highly monodispersed manganese ferrite nanoparticles (MNPs, 6 nm) with mPEG‐g‐PEI and PEG coatings as model system are employed in this study to investigate the coating engineering for simultaneously high T2 relaxivity and cellular uptake. The quantitative evaluations of the intracellular uptake indicate that mPEG‐g‐PEI modified MNPs possess highly efficient cellular uptake, 2.4‐fold larger than that with mPEG coating. More significantly, this coating simultaneously leads to a remarkably high T2 relaxivity up to 331.8 mm−1 s−1, which is 4 times larger than that of the mPEG control and the largest value reported for superparamagnetic iron oxides with similar size. Modeling analysis reveals that the superior relaxivity is mainly attributed to the largely reduced diffusivity of water molecules trapped in the mPEG‐g‐PEI net. Further MRI of MDA‐MB‐231 breast cancer cells loaded MNPs with mPEG‐g‐PEI coating demonstrated the strong MR contrast in vitro effect with a T2 relaxivity as high as 92.6 mm−1 s−1, 2.5‐folds larger than reported 10 nm MNPs. This study provides a universal strategy of coating engineering of various magnetic nanoparticles for highly sensitive MRI.

Background: Recurrent Functional Chest pain (FCP) with normal coronary anatomy and no detectable gastroenterological and respiratory causes is a common problem that sometimes leads to excess use of medical care. Objective: The purpose of this meta-analysis is to investigate the efficacy of antidepressant treatments for FCP. Settings: MEDLINE, PsycINFO, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to July 2011. Randomized controlled trials (RCTs) that tested any type of antidepressants for FCP with normal coronary anatomy were analyzed. Diagnoses included non-specific chest pain, noncardiac chest pain, atypical chest pain, syndrome X, or chest pain with normal coronary anatomy. Methods: Two authors independently extracted data. Effects were summarized using standardized mean differences (SMDs), weighed mean differences (WMD), or odds ratio (OR) by suitable effects model. Results: Seven RCTs (median duration, 5 weeks; range, 3 - 16 weeks) involving 319 participants were included. There was strong evidence for an association of antidepressants with reduction in pain (SMD −1.26; 95% confidence interval [CI], −2.34 to −0.19) and psychological symptoms (SMD −0.87; 95% CI, −1.67 to – 0.08) as well as increased side effects (OR 0.34; 95% CI, 0.15 to 0.78). Current analysis did not support the association of antidepressants with improved health related quality of life (WMD 2.00; 95% CI, − 2.54 to – 6.65). Limitations: Demographics, co-morbidities of study participants and the amount of comedication were not reported, these possible sources of heterogeneity could not be examined. Conclusions: Antidepressant medications are associated with improvements in pain and psychological symptoms. The effects of factors including psychiatric co-morbidity, gender, age, ethnic group, and treating period on the outcomes should be checked further. Key words: Functional chest pain, antidepressants, meta-analysis