Due to the prevalence of cardiovascular diseases, there is a large need for small diameter vascular grafts that cannot be fulfilled using autologous vessels. Although medium to large diameter synthetic vessels are in use, no suitable small diameter vascular graft has been developed due to the unique dynamic environment that exists in small vessels. To achieve long term patency, a successful tissue engineered vascular graft would need to closely match the mechanical properties of native tissue, be non-thrombotic and non-immunogenic, and elicit the proper healing response and undergo remodeling to incorporate into the native vasculature. Electrospinning presents a promising approach to the development of a suitable tissue engineered vascular graft. This review provides a comprehensive overview of the different polymers, techniques, and functionalization approaches that have been used to develop an electrospun tissue engineered vascular graft.

Aromatic hydrocarbons trigger a green luminescence on their association to a β-cyclodextrin (CD) modified with a Tb3+ diethylenetriaminepentaacetic acid (DTPA) macrocycle strapped across the bottom of the CD cup, [β-CD∪2(Tb⊂DTPA)]. The mechanism of this enhanced luminescence response is investigated with biphenyl as the aromatic hydrocarbon. Time-resolved emission spectroscopy reveals that excitation energy at the Tb3+ ion appears 12 μs after light is absorbed by biphenyl included within the CD cup. Excitation spectra are consistent with a photophysical mechanism comprising absorption-energy transfer-emission (AETE) from the aromatic hydrocarbon bound to the cavity of CD to the DTPA-encapsulated Tb3+ ion. A comparison of the luminescence decay kinetics for biphenyl associated to [β-CD∪2(Tb⊂DTPA)] and [β-CD∪2(Gd⊂DTPA)] complexes indicates that the pathway for the AETE process is absorption to the singlet excited state followed by intersystem crossing to the triplet, from which energy is transferred to the lanthanide ion.

Two electrons in two weakly coupled orbitals give rise to two states (diradical) with electrons residing in separate orbitals and two states (zwitterionic) with both electrons paired in one orbital or the other. This two-electron, two-orbital state manifold has eluded experimental confirmation because the zwitterionic states have been difficult to locate. Two-photon excitation of fluorescence from Mo(2)CI(4)(PMe(3))(4) (D2d) has been measured with linearly and circularly polarized light. From the polarization ratio and the energy of the observed transition, the 2(1)A(1) (delta*delta*) excited state has been located and characterized. In conjunction with the one-photon allowed (1)B(2) (deltadelta*) excited state, the zwitterionic state manifold for the quadruply bonded metal-metal class of compounds is thus established.

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