Activatable MRI probes for the specific detection of bacteria.

Activatable fluorescent probes have been successfully used as molecular tools for biomedical research in the last decades. Fluorescent probes allow the detection of molecular events, providing an extraordinary platform for protein and cellular research. Nevertheless, most of the fluorescent probes reported are susceptible to interferences from endogenous fluorescence (background signal) and limited tissue penetration is expected. These drawbacks prevent the use of fluorescent tracers in the clinical setting. To overcome the limitation of fluorescent probes, we and others have developed activatable magnetic resonance probes. Herein, we report for the first time, an oligonucleotide-based probe with the capability to detect bacteria using magnetic resonance imaging (MRI). The activatable MRI probe consists of a specific oligonucleotide that targets micrococcal nuclease (MN), a nuclease derived from Staphylococcus aureus. The oligonucleotide is flanked by a superparamagnetic iron oxide nanoparticle (SPION) at one end, and by a dendron functionalized with several gadolinium complexes as enhancers, at the other end. Therefore, only upon recognition of the MRI probe by the specific bacteria is the probe activated and the MRI signal can be detected. This approach may be widely applied to detect bacterial infections or other human conditions with the potential to be translated into the clinic as an activatable contrast agent.

Fibrin hydrogel incorporated with graphene oxide functionalized nanocomposite scaffolds for bone repair - In vitro and in vivo study.

Conventional bone repair therapies like the autologous and allogenic bone grafts have failed to meet challenges in bone reconstruction along with complications. Tissue engineering (TE) has emerged as a developing treatment regimen in regenerating damaged tissues rather than replacing them. In TE, biomaterials act as template for damaged tissues and function as artificial extracellular matrix (ECM), facilitating new tissue formation. Since single type biomaterial has unsuccessful regeneration properties, focus on using composites of natural and synthetic biomaterials is encouraged. In the current study, we have evaluated the potential of a graphene-based nano-composite scaffold as a biomaterial to enhance bone tissue regeneration. The findings demonstrate that the scaffold with Graphene oxide (GO) exhibits enhanced levels of biocompatibility, alkaline phosphatase activity, and calcium deposits, thereby emphasizing the hypothesis that fabricated nanocomposite scaffolds are promising osteoinductive products for bone repair/regeneration.

Macrophages mediated diagnosis of rheumatoid arthritis using fibrin based magnetic nanoparticles as MRI contrast agents.

BACKGROUND: A variety of bioimaging tools assists in the diagnosis and evaluation of rheumatoid arthritis (RA) and other osteoarthritis. However, detection of RA in the early stages by targeting its macrophages with suitable contrast agents will help in arresting the progression of the disease. METHODS: In the present study, we investigated the effectiveness of using magnetic fibrin nanoparticles (MFNPs) conjugated with folic acid (FA-MFNPs) as a specific contrast agent to target the activated macrophages, which overexpress the folate receptors (FR) in the knee joints of rats with antigen-induced arthritis (AIA). RESULTS: FA-MFNPs were spherical with an average size of 18.3±1.6nm. In vitro studies have shown effective internalization of FA-MFNPs into the Raw264.7 macrophage cells. In vivo studies were carried out by injecting FA-MFNPs intravenously into the arthritic rats. The results showed enhanced MR imaging in the synovium of arthritic joints. Prussian blue histological staining confirmed uptake of FA-MFNPs by macrophages in the synovial tissue. CONCLUSION: The animal experiment results indicate that FA-MFNPs can be used as a specific MRI contrast agent in identifying phagocytic active macrophages in the synovial joints. GENERAL SIGNIFICANCE: Blood is the precursor source for synthesising the fibrin-based iron oxide (magnetic) nanoparticles (MFNPs) with diameters between 12 and 15nm. It has excellent superparamagnetic behaviour, biocompatibility, osteogenic potency, hemocompatibility, and biodegradable properties. MFNPs-based nanocomposites might be a promising contrast agent for bioimaging.