Chemical nature and structure of organic coating of quantum dots is crucial for their application in imaging diagnostics.

BACKGROUND: One of the most attractive properties of quantum dots is their potential to extend the opportunities for fluorescent and multimodal imaging in vivo. The aim of the present study was to clarify whether the composition and structure of organic coating of nanoparticles are crucial for their application in vivo. METHODS: We compared quantum dots coated with non-crosslinked amino-functionalized polyamidoamine (PAMAM) dendrimers, quantum dots encapsulated in crosslinked carboxyl-functionalized PAMAM dendrimers, and silica-shelled amino-functionalized quantum dots. A multimodal fluorescent and paramagnetic quantum dot probe was also developed and analyzed. The probes were applied intravenously in anesthetized animals for visualization of brain vasculature using two-photon excited fluorescent microscopy and visualization of tumors using fluorescent IVIS(®) imaging (Caliper Life Sciences, Hopkinton, MA) and magnetic resonance imaging. RESULTS: Quantum dots coated with non-crosslinked dendrimers were cytotoxic. They induced side effects in vivo, including vasodilatation with a decrease in mean arterial blood pressure and heart rate. The quantum dots penetrated the vessels, which caused the quality of fluorescent imaging to deteriorate. Quantum dots encapsulated in crosslinked dendrimers had low cytotoxicity and were biocompatible. In concentrations <0.3 nmol quantum dots/kg bodyweight, these nanoparticles did not affect blood pressure and heart rate, and did not induce vasodilatation or vasoconstriction. PEGylation (PEG [polyethylene glycol]) was an indispensable step in development of a quantum dot probe for in vivo imaging, based on silica-shelled quantum dots. The non-PEGylated silica-shelled quantum dots possessed low colloidal stability in high-salt physiological fluids, accompanied by rapid aggregation in vivo. The conjugation of silica-shelled quantum dots with PEG1100 increased their stability and half-life in the circulation without significant enhancement of their size. In concentrations <2.5 nmol/kg bodyweight, these quantum dots did not affect the main physiological variables. It was possible to visualize capillaries, which makes this quantum dot probe appropriate for investigation of mediators of vasoconstriction, vasodilatation, and brain circulation in intact animals in vivo. The multimodal silica-shelled quantum dots allowed visualization of tumor tissue in an early stage of its development, using magnetic resonance imaging. CONCLUSION: THE PRESENT STUDY SHOWS THAT THE TYPE AND STRUCTURE OF ORGANIC/BIOORGANIC SHELLS OF QUANTUM DOTS DETERMINE THEIR BIOCOMPATIBILITY AND ARE CRUCIAL FOR THEIR APPLICATION IN IMAGING IN VIVO, DUE TO THE EFFECTS OF THE SHELL ON THE FOLLOWING PROPERTIES: colloidal stability, solubility in physiological fluids, influence of the basic physiological parameters, and cytotoxicity.

The influence of accessory right inferior hepatic veins on the venous drainage in right graft living donor liver transplantation.

BACKGROUND/AIMS: Proper venous outflow reconstruction is essential for the success of living donor liver transplantation (LDLT). It has also a decisive impact on postoperative graft dysfunction. The accessory right inferior hepatic veins (IHVs) usually drain parts of the lateral sector of the right hemiliver graft (RHL). The purpose of our study was to: (1) evaluate the drainage patterns of the IHVs in right hemiliver grafts; (2) analyze the influence of IHVs on the dominance relationships between the right and middle hepatic veins in RHL's; (3) evaluate some potential correlation between drainage patterns of IHVs and the portal vein anatomy. METHODOLOGY: We analyzed 3-dimensional CT-imaging reconstructions of 71 potential live liver donors evaluated at our Institution between January 2003 and October 2004. RESULTS: (1) Thirty-six (51%) donors had inferior hepatic veins (IHV) with detectable venous drainage territories, (2) the RHV/IHV-complex was dominant in 97% of cases, and the RHV as a single veinwithout anatomical IHV was dominant in 94% of right hemiliver grafts, (3) 27 of 71 livers (38%) showed a central (n=11) or peripheral (n=16) PV anomaly, (4) IHV provided a mean 32% of venous drainage in the right lateral sector, and in some cases drained up to 25% of the right medial sector irrespective of the PV anatomy, (5) such cases required IHV reconstruction to prevent severe tissue congestion in the right hemiliver graft. CONCLUSIONS: Accurate insight into the drainage patterns of the right and middle hepatic veins and precise knowledge of the functional volume drained by the IHV are essential when planning for the proper outflow reconstruction of right hemiliver grafts in LDLT.