**Author details**

334 Practical Applications in Biomedical Engineering

silanized particles were conjugated to oleyl-O-poly(ethylene glycol)succinyl-Nhydroxysuccinimidyl ester through binding of the surface amine groups with heterofunctional polyethylene glycol. The biocompatible silica-coated can effectively target the cell membranes of HepG2 human liver cancer cells, NIH-3T3 mouse fibroblast cells, and 4T1 mouse breast cancer cells. These results demonstrated that these materials have

The biological applications of the down-conversion luminescent materials are currently restricted because they frequently emit at UV and visible regions, given the autofluorescence from biological tissues. These limitations would be breakthrough if we discover an alternate materials emitted in near-infrared (NIR)-to-vis upconversion.[80] This expectation was proved by Stucky et al.[81] who recently developed the new mesoporous multifunctional materials based on the combination of both up-converting luminescent and magnetic properties. Nanorattle hollow spheres consisted of the rare-earth-doped NaYF4 shells with a SiO2-coated Fe3O4 inner particle fabricated through ion-exchange process. The silica coating of the Fe3O4 nanoparticles were carried out by hydrolysis of TEOS in reverse-microemulsion system. The Fe3O4@SiO2@Y2O3/Yb,Er magnetic upconversion oxide nanospheres were prepared by coating with the layer of Y/Yb,Er(OH)CO3.H2O via homogeneous precipitation in the aqueous solution of yttrium nitrate and urea and subsequent calcination at 550 oC for 2 h. The Fe3O4@SiO2@α-NaYF4/Yb,Er magnetic upconversion uoride nanorattles were formed via ion-exchange of the Fe3O4@SiO2@Y2O3/Yb,Er particles in HF and NaF solution. To demonstrate the material's potential use as a drug delivery system, the magnetic upconversion uoride nanorattles were conjugated with antitumor drug doxorubicin. Through in vitro experiments in mice cells, the authors demonstrated that the material emits visible luminescence upon NIR excitation and can be directed by external magnetic field to specific target, making it an attractive system for targeted chemotherapy. **Figure 10** shows the use of mesoporous silica-coated NaYF4:Yb,Er upconversion fluorescent nanoparticles (UCNs) as a remote-controlled nanotransducer for photodynamic therapy reported by Zhang et al.[82] The nanoparticle matrix can efficiently upconvert the energy of penetrating near-infrared light to visible light and transfer it to the encapsulated photosensitizers. The UCN materials exhibited a spectral overlap between the emitted visible light and the maximum absorption wavelengths of the photosensitizers to generate cytotoxic singlet oxygen in water. The authors discovered that the inhibition of tumor-cell growth in mice as a result of singlet oxygen generation from the UCNs, even at a very low 980-nm laser powers. This enabled selective fluorescent labelling, imaging and potentially sorting of the

potential for drug loading and delivery into cancer cells to induce cell death.

cells opening new prospects in cancer diagnostics and therapy.

Most strategies of conjugating functional surfaced nanoparticles with biomolecule imaging agents produce antibody-conjugated particles that are considered as efficient biomedical diagnosis agents and universal platforms for engineering of multifunctional nanodevices. Inorganic nanohybrids containing more than one component have drawn considerable interest

**7. Conclusions and outlooks** 

Thai-Hoa Tran *Department of Chemistry, Faculty of Sciences, Hue University, Hue 84054, Vietnam* 

Thanh-Dinh Nguyen**\*** *Department of Chemical Engineering, Laval University, Quebec G1K 7P4, Canada* 

<sup>\*</sup> Corresponding Author

#### **Acknowledgement**

This work was supported by the National Foundation for Science and Technology development of Vietnam-NAFOSTED (No. 104.03-2012.54).

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**Section 3** 

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**Biomedical Image Processing** 

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**Chapter 14** 

© 2012 Constantinides, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Constantinides, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Study of the Murine Cardiac Mechanical** 

**The Current Status, Challenges, and** 

**Future Perspectives** 

Additional information is available at the end of the chapter

Christakis Constantinides

http://dx.doi.org/10.5772/51364

**1. Introduction** 

**Function Using Magnetic Resonance Imaging:** 

While cardiac mechanical function studies initially focused on large mammals and the human, the mouse emerged as the preferred animal species for such research in recent years [Collins 2003]. Despite the fact that evidence supports that bio-energetically and hemodynamically the mouse scales in a linear fashion with larger mammals and humans [Dobson 1995, Nielsen 1958], nevertheless, important physiological questions still remain [Kass 1998, Balaban 2001] on whether such a model is the most appropriate for extrapolation of conclusions to man [Schaper 1998, Balaban 2012]. With the complete characterization of the mouse and human genomes (a National Institutes of Health initiative) in 2002 and 2003 respectively [Collins 2003, Gregory 2002], a plethora of mouse studies emerged targeting the cardiovascular system in animals with genetic modifications [James 1998, Hoit 2001, Gehmann 2000, Ehmke 2003], marking the onset of the molecular physiology, proteomics, and (structural and functional) genomics era. Collectively, these studies [Milano 1994, Barbee 1994, MacGowan 2001] initially targeted six important areas of cardiac function including the: *(a) excitation-contraction cascade*; *(b) the beta-adrenergic system*; *(c) the cytosolic/structural system and the cytoskeleton*; *(d) the extracellular matrix and its coupling to important cytosolic elements that assist the mechanical force generation or propagation*; *(e) molecules that determine spatial-temporal mechanical changes (due to differential gene expression, phosphorylation, or recruitment of fetal development gene programs)*; and *(f) the energetic-metabolic status of the muscle*. Equally important in most of these studies was the non-invasive imaging of such animals for phenotypic and genotypic screening, often conducted under inhalational anesthesia [Erhart 1984, Hart 2001, Price 1980, Kober 2005, Constantinides\_ILAR 2011].
