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Research Interests

Today, biomedical imaging techniques like MRI, CT and PET are corner stones for management of patients suffering from heart disease, stroke, cancer or autoimmune disease. Further developments of targeted contrast agent and novel imaging modalities will pave the way for personalized therapy and high precision treatments in the near future. Short-wave infrared (SWIR) Imaging is an emerging technology involving novel, targeted nanoparticles that shows a high potential for clinical imaging applications in the new era of personalized medicine.

My research is committed to develop excellent techniques for biomedical imaging. The emphasis is on applying novel nanomaterials and technologies for next generation imaging. For these highly interdisciplinary studies I built a network of collaborators ranging from physics and chemistry over biology to preclinical and clinical research groups. My expertise is the functionalization and biological characterization of novel nanocrystals (e.g. fluorescent, magnetic or gold nanocrystals) and organics dyes for targeted biomedical imaging. With my experience I can now connect state of the art developments in material science, chemistry and imaging techniques with preclinical and clinical research to advance the translation of newest imaging technologies into clinical applications.

My educational background is biochemistry, biomedical imaging and cell biology. I always worked with interdisciplinary teams, combined complementary expertise and gathered the best research tools to push exciting discoveries. During my scientific career I focused on the interface between novel nanomaterials, state-of-the-art microscopy and whole body imaging techniques and applied this combination to answer basic research questions and engineer novel solution for real world medical problems.

First, I developed a novel technique to label lipoproteins in my diploma thesis, than I used this technique to investigate lipoprotein metabolism in the context of atherosclerosis and diabetes research. Next, I started to apply magnetic resonance imaging (MRI) in collaboration with the clinic of Prof. Adam in Hamburg. This collaboration led to a novel quantitative MR imaging technique (Bruns et al. Nature Nanotechnology 2009; Patent No.: WO/2012/098226). Next we used our new nanostructures to sense the metabolic activity of brown adipose tissue in a multimodal approach (high-speed confocal imaging, MRI and TEM and SEM) (Bartelt, Bruns, et al. Nature Medicine 2011). While I was a senior scientist in the group of Dr. Hohenberg at the Heinrich-Pette-Institute for Experimental Virology I also collaborated with PD Dr. Herkel to develop a novel nanoparticles based therapeutic approach for multiple sclerosis (Carambia et al., Journal of Hepatology 2015; Patent No: WO/2013/072051). This idea is currently translated into clinical practice by the newly formed company TOPAS Therapeutics, funded with more than $ 14,000,000.

Coming to MIT as a postdoc I started setting up in vivo animal work in the lab of Moungi Bawendi, for which he previously had to collaborate with other groups at MGH and other hospitals. I led the efforts to develop and establish whole body and intravital short-wave infrared (SWIR) imaging (Bruns et al. Nature Biomedical Engineering 2017; US Provisional Patent application 61/814,528) at MIT for cutting edge in vivo studies. Our lab at MIT now is conducting in vivo imaging studies in close collaboration with laboratories at Massachusetts General Hospital (MGH) and Harvard School of Public Health. In addition I also led the efforts for in vivo characterization and imaging applications of a novel MRI agent (Wei, Bruns et al. PNAS 2017; Wei, Bruns et al. Integrative Biology 2012).

Advanced materials as novel contrast agents for fluorescence imaging

 

After developing techniques for labelling lipoproteins for metabolic imaging and sensing as well as targeting specific cell populations in vivo during my PhD and postdoc in Hamburg I decided to strengthen my background in development of advanced materials for near infrared imaging. For this I joined the group of Moungi Bawendi at MIT which is not only one of the leading groups for developing novel nanoparticles, but also in fundamental spectroscopic studies and novel strategies for biofunctionalization and targeting of these materials. Through the interactions at MIT I also developed a deeper understanding of the fundamental optical processes at play and learned how to optimize an optical contrast agent for a particular application.

For fluorescence imaging it is important to optimize the brightness which is defined as the product of absorption cross section and quantum yield. While some materials emitting in the infrared have a good absorption cross section (e.g. carbon nanotubes (CNTs)), they often suffer from very low quantum yields (0.1% or 0.001 for CNTs). Other materials (e.g. rare earth doped nanoparticles or special donor-acceptor dyes) can exhibit higher quantum yields (around 1-2% or 0.01) but have a very low absorption cross section.

Quantum dots are an excellent class of labels as they combine both a high molar absorption cross section with the highest quantum yield (up to 30% or 0.3) achieved so far in the infrared.

SWIR for next-generation in vivo imaging

 

The SWIR region (short-wavelength infra-red / between 1000 nm and 2000 nm) of the optical spectrum is the optimal region for non-invasive optical bioimaging as scattering is highly suppressed and absorption of blood and autofluorescence are almost absent. Recent progress in detection technology and the development of new contrast agents allowed to demonstrate that SWIR imaging is superior to most other label based imaging techniques.

Awards

2006-2009 Fellowship by ‘Studienstiftung des Deutschen Volkes’ (German National Academic Foundation)
2006 Award for the best diploma thesis in Biochemistry/Molecular Biology
2007 Young Investigator Award, 30th annual Meeting of European Lipoprotein Club, Tutzing, Germany
2008 Young Investigator Award, 77th European Atherosclerosis Congress, 2008, Istanbul, Turkey
2010 Karl-Heinz Hölzer PhD-Award for Interdisciplinary Medical Research
2011 EMBO Long-Term Fellowship

 

Selected publications

Wei H, Bruns OT, Kaul MG, Hansen EC, Barch M, Wisniowska A, Chen O, Chen Y, Li N, Okada S, Cordero JM, Heine M, Farrar CT, Montana DM, Adam G, Ittrich H, Jasanoff A, Nielsen P, and Bawendi MG. Exceedingly small iron oxide nanoparticles as positive MRI contrast agents. Proceedings of the National Academy of Sciences of the United States of America. 2017, 114, 2325-2330.

Bruns OT, Bischof TS, Harris DK, Franke D, Shi Y, Riedemann L, Bartelt A, Jaworski FB, Carr JA, Rowlands CJ, Wilson MWB, Chen O, Wei H, Hwang GW, Montana DM, Coropceanu I, Achorn OB, Kloepper J, Heeren J, So PTC, Fukumura D, Jensen KF, Jain RK, Bawendi MG. Next-generation in vivo optical imaging with short-wave infrared quantum dots. Nature Biomedical Engineering. 2017, 1, .

Carr JA, Valdez T, Bruns OT, Bawendi MG. Using the shortwave infrared to image middle ear pathologies. Proceedings of the National Academy of Sciences of the United States of America. 2016, 113, No. 36, 9989–9994.

Franke D, Harris DK, Chen O, Bruns OT, Carr JA, Wilson MWB, Bawendi MG. Continuous injection synthesis of indium arsenide quantum dots emissive in the short-wavelength infrared. Nature Communications. 2016, , 12749.

Rowlands CJ, Park D, Bruns OT, Piatkevich K, Fukumura D, Jain RK, Bawendi MG, Boyden E, So PTC. Wide-field Three-Photon Excitation in Biological Specimens.. Light: Science & Applications. 2016, 5, 123-144.

Rowlands CJ, Bruns OT, Bawendi MG, So PTC. Objective, comparative assessment of the penetration depth of temporal-focusing microscopy for imaging various organs. Journal of Biomedical Optics. 2015, 20, 061107.

Lemon CM, Karnas E, Han X, Bruns OT, Kempa TJ, Fukumura D, Bawendi MG, Jain RK, Duda DG, Nocera DG.. Micelle-Encapsulated Quantum Dot-Porphyrin Assemblies as in Vivo Two-Photon Oxygen Sensors. Journal of the American Chemical Society. 2015, 137 , 9832–9842.

Chen O, Riedemann L, Etoc F, Herrmann H, Coppey M, Barch M, Farrar CT, Zhao J, Bruns OT, Wei H, Guo P, Cui J, Jensen R, Chen Y, Harris DK, Cordero JM, Wang Z, Jasanoff A, Fukumura D, Reimer R, Dahan M, Jain RK, Bawendi MG. Magneto-fluorescent core-shell supernanoparticles. Nature Communications. 2014, 5, 5093.

Wei H, Bruns OT, Chen O, Bawendi MG. Compact zwitterion-coated iron oxide nanoparticles for in vitro and in vivo imaging. Integrative Biology. 2013, 5, 108-114.