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The understanding of the endocytosis process of internalized nanomedicines through membrane biomarker is essential for the development of molecular-specific nanomedicines. In various recent reports, the metalloproteases have been identified as important markers during the metastasis of cancer cells. In particular, MT1-MMP has provoked concern due to its protease activity in the degradation of the extracellular matrix adjacent to tumors. Thus, in the current work, we have applied fluorescent Au nanoclusters which present strong resistance to chemical quenching to the investigation of MT1-MMP-mediated endocytosis. We synthesized protein-based Au nanocluster (PAuNC) and MT1-MMP-specific peptide was conjugated with PAuNC (pPAuNC) for monitoring protease-mediated endocytosis. The fluorescence capacity of pPAuNC was investigated and MT1-MMP-mediated intracellular uptake of pPAuNC was subsequently confirmed by a co-localization analysis using confocal microscopy and molecular competition test. Furthermore, we confirmed a change in the intracellular lipophilic network after an endocytosis event of pPAuNC. The identical lipophilic network change did not occur with the endocytosis of bare PAuNC. By classification of the branched network between the lipophilic organelles at the nanoscale, the image-based analysis of cell organelle networking allowed the evaluation of nanoparticle internalization and impaired cellular components after intracellular accumulation at a single-cell level. Our analyses suggest a methodology to achieve a better understanding of the mechanism by which nanoparticles enter cells. [ABSTRACT FROM AUTHOR]

Structural and energetic properties of nanoclusters of Au, Li, and LiAu ( n = 1-6) were studied employing MP2, M062X, and B3LYP computational methods. The planar (2D) isomers were the most stable structures of the Au clusters. Binding energy per atom ( E) for the Au clusters increased with increase in the cluster size and were in the range of 0.9-1.7 eV. The Li clusters were more unstable, and their E values were about 0.4-0.6 eV. Lithium-doping of Au clusters resulted in an increase of E values and more stable clusters. Also, Li-doping led to stability of the 3D clusters so that the bipyramidal AuLi isomer became more stable than the planar clusters. It was observed that the electron affinities of the Au, Li, and LiAu clusters increased with cluster sizes. Ionization energies and electron affinities of the Li-doped gold clusters were smaller than those for pure Au clusters. [ABSTRACT FROM AUTHOR]

Taking Au as a prototype, hollow cages with different arrangements and those stuffed by a different number of atoms have been studied by using the scalar relativistic density functional theory. The global minimum structures of Au ( i = 0, ±1) are found to exhibit low symmetry core-shell structures: Au and Au feature a four-atom tetrahedral core and Au possesses a six-atom octahedron core. For the neutral Au, the tube-like structure has the highest chemical stability. The obtained information forms the basis for future chemisorption studies to unravel the catalytic effects of gold nanoparticles. [ABSTRACT FROM AUTHOR]