Hyperbranched poly(amido amine) (HPAMAM), which is structurally analogous to PAMAM dendrimers, has been proposed to be an effective agent for gene delivery. The facile synthesis of HPAMAM with scalable productivity by one-pot polymerization of monomers of methyl acrylate (MA) and diethylenetriamine (DETA) has been set up previously. In this study, the HPAMAM was further modified on the terminal amino groups with phenylalanine to various degrees (HPAMAM-PHE30, PHE45, PHE60). We showed that HPAMAM and HPAMAM-PHEs were all able to form complexes with plasmid DNA (pDNA) at various mass ratios. The cytotoxicity and transfection efficiencies of these polymers were evaluated in SMMC-7721 and COS-7 cell lines. The PHE modifications affected the cell transfection efficiency significantly. The HPAMAM-PHE60 was the most efficient, with transfection activities consistently higher than the commercial transfection reagent PEI. Our study demonstrated that HPAMAM-PHEs may be good new materials for gene delivery and other applications because of its large-scale availability, economical cost, and low toxicity.

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Amyloid fibrils are considered to play causal roles in the pathogenesis of amyloid-related degenerative diseases such as Alzheimer's disease, type II diabetes mellitus, the transmissible spongiform encephalopathies, and prion disease. The mechanism of fibril formation is still hotly debated and remains an important open question. In this study, we utilized molecular dynamics (MD) simulation to analyze the stability of hexamer for eight class peptides. The MD results suggest that VEALYL and MVGGVV-1 are the most stable ones, then SNQNNY, followed by LYQLEN, MVGGVV-2, VQIVYK, SSTSAA, and GGVVIA. The statistics result indicates that hydrophobic residues play a key role in stabilizing the zipper interface. Single point and two linkage mutants of MVGGVV-1 confirmed that both Met1 and Val2 are key hydrophobic residues. This is consistent with the statistics analysis. The stability results of oligomer for MVGGVV-1 suggest that the intermediate state should be trimer (3-0) and tetramer (2-2). These methods can be used in stabilization study of other amyloid fibril.

3D reconstruction of urban architecture, land, and roads is an important part of building a “digital city.” Unmanned aerial vehicles (UAVs) are gradually replacing other platforms, such as satellites and aircraft, in geographical image collection; the reason for this is not only lower cost and higher efficiency, but also higher data accuracy and a larger amount of obtained information. Recent 3D reconstruction algorithms have a high degree of automation, but their computation time is long and the reconstruction models may have many voids. This paper decomposes the object into multiple regional parallel reconstructions using the clustering principle, to reduce the computation time and improve the model quality. It is proposed to detect the planar area under low resolution, and then reduce the number of point clouds in the complex area.

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