Tumor‐Specific Aptamer‐Conjugated Polymeric Photosensitizer for Effective Endo‐Laparoscopic Photodynamic Therapy

Recent advances in medical technology and endo‐laparoscopic devices have enabled the treatment of gastrointestinal (GI) cancers to be minimally invasive through endo‐laparoscopic photodynamic therapy (PDT). To achieve an efficient regional or endo‐laparoscopic PDT, it is necessary to develop a highly target specific photosensitizer (PS) that can be easily treated to the lesion site with endo‐laparoscopic device. Here, an ideal polymeric PS is demonstrated for effective endo‐laparoscopic PDT. In the synthetic process, conventional PS (i.e., Chlorin e6, Ce6) is conjugated with an Aptamer (i.e., AS1411) targeting nucleolin (also called C23) overexpressed on the cancer cell membrane using a water‐soluble polymeric linker (i.e., polyethylene glycol, PEG). The synthesized Aptamer‐PEG‐Ce6 could target nucleolin‐overexpressing tumor cells efficiently and visualize the tumor tissues through optical and fluorescent imaging both in vitro and ex vivo, and effectively kills cancer cells under laser irradiation. Tumor staining with Aptamer‐PEG‐Ce6 is easily accomplished through endoscopic equipment within a few minutes. Furthermore, after laser irradiation, Aptamer‐PEG‐Ce6 is found to penetrate deeply into the tumor tissue and induce apoptosis of tumor cells. Taken together, the tumor‐specific Aptamer‐conjugated polymeric PS developed in this study has great potential as an ideal photomedicine for effective tumor treatment using endo‐laparoscopic PDT.     

Targeted Delivery of CRISPR/Cas9‐Mediated Cancer Gene Therapy via Liposome‐Templated Hydrogel Nanoparticles

Due to its simplicity, versatility, and high efficiency, the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 technology has emerged as one of the most promising approaches for treatment of a variety of genetic diseases, including human cancers. However, further translation of CRISPR/Cas9 for cancer gene therapy requires development of safe approaches for efficient, highly specific delivery of both Cas9 and single guide RNA to tumors. Here, novel core–shell nanostructure, liposome‐templated hydrogel nanoparticles (LHNPs) that are optimized for efficient codelivery of Cas9 protein and nucleic acids is reported. It is demonstrated that, when coupled with the minicircle DNA technology, LHNPs deliver CRISPR/Cas9 with efficiency greater than commercial agent Lipofectamine 2000 in cell culture and can be engineered for targeted inhibition of genes in tumors, including tumors the brain. When CRISPR/Cas9 targeting a model therapeutic gene, polo‐like kinase 1 (PLK1), is delivered, LHNPs effectively inhibit tumor growth and improve tumor‐bearing mouse survival. The results suggest LHNPs as versatile CRISPR/Cas9‐delivery tool that can be adapted for experimentally studying the biology of cancer as well as for clinically translating cancer gene therapy.     

Contingency and serendipity in the reactions of Fischer carbene complexes with conjugated triynes

The first examples of reactions of Fischer carbene complexes with triynes are reported. The regioselectivity of the reaction of the two different alkyne functions in the symmetrical triyne depends on the nature of the substituent of the triyne. Bis-silyl-substituted triynes react at the central alkyne unit, whereas bis-aryl- and bis-alkyl-substituted triynes react at the end alkyne unit. The reaction of a Fischer carbene complex with a phenyl substituent also reacts with a bis-silyl-substituted triyne at the central alkyne unit but gives a furan product rather than the normal phenol product. It was also demonstrated that all three of the alkyne units in conjugated triynes could react in turn with a Fischer carbene complex to give access to trisquinones.     

High-performance liquid chromatographic enantiomeric separation of an enzyme inhibitor which possesses both a chiral center and tautomeric moieties

The enantiomeric separation using high-performance liquid chromatography (HPLC) on chiral stationary phases (CSPs) of a chiral compound which exists in solution in several tautomeric forms is described. 2,4-Dioxo-5-acetamido-6-phenylhexanoic acid is the most potent inhibitor known for peptidylamidoglycolate lyase (PGL, EC 4.3.2.5), an enzyme which plays an essential role in carboxyl-terminal amidation of many biological peptides. Synthesis of this inhibitor entails an alkaline hydrolysis step, under which condition the compound is racemized; thus, HPLC with a CSP was employed to obtain the individual enantiomers of this inhibitor. Since 2,4-dioxo-5-acetamido-6-phenylhexanoic acid exists in solution in several tautomeric forms, the strategy of first converting this compound from its multiple enol forms into a single diketo tautomer, which was then applied to various CSPs, was employed. Successful preparative scale enantiomeric separation of this compound was achieved using a Chiralpak AD CSP. Enantiomeric separation was also accomplished on a D-penicillamine column, but this CSP was found to be less satisfactory for preparative purposes.     

Further evaluation and development of charge similarity indices for choosing molecular analogues

Two molecular charge similarity index (CSI ) methods are further evaluated for practical application: one method based on a simple CNDO -type approximation to the electron density function and the other based on an ab initio pseudo total charge density function. The test system consists of isosteric analogues of dimethyl ether and methoxy acetic acid. The effects of differences in skeletal structure on the CSI measure of electron density similarity about corresponding atoms is estimated, and two new developments are presented for application of the ab initio-based method: (1) an INDO -type approximation which improves the efficiency of the CSI calculation; and (2) a FOCUS feature which enables comparisons of local molecule regions.     

Derivatized amino acids relevant to native peptide synthesis by chemical ligation and acyl transfer

Three amino acids were converted into the derivatives 5.2 (from glycine), 6.4a and 6.4b (from alanine), and 8.3a and 8.3b (from O-benzyl serine). These N-alkylated amino acids, which can be deprotected after conversion of the carboxyl into an amide, correspond to the general structure 2.1, a compound class of use in the study of peptide segment coupling by the ligation-acyl transfer method.     

Structural refinement of the high-pressure phase of aluminum trihydroxide: in-situ high-pressure angle dispersive synchrotron X-ray diffraction and theoretical studies

In-situ high-pressure synchrotron angle-dispersive X-ray diffraction for gibbsite (aluminum trihydroxide) was performed at room temperature up to 20 GPa. A pressure-induced phase transition was observed at 2.6 GPa. The new high-pressure phase can be recovered at ambient pressure. Rietveld refinement shows that the new phase of Al(OH)(3) has an orthorhombic structure, spacegroup Pbca, and the lattice parameters at ambient condition are a = 868.57(5) pm, b = 505.21(4) pm, c = 949.54(6) pm, V = 416.67(6) x 10(6) pm(3) with Z = 8. The compressibility of gibbsite and the high-pressure polymorph was analyzed, and their bulk moduli were estimated as 49.8 +/- 1.8 and 81.0 +/- 5.2 GPa, respectively. First-principles calculations of the high-pressure phase were performed to determine the hydrogen positions and to confirm the structural stability of the new phase.     

Dynamics or Stochastic Conductance Switching of Phenylene–Ethynylene Oligomers?

Scanning tunneling microscopy (STM) studies of phenylene-ethynylene oligomers inserted in alkanethiolate self assembled monolayers (SAMs) are presented. Spontaneous changes in appearance of bundles of inserted molecules during imaging are observed. The results indicate that the appearance changes are caused by fluctuations of the number of molecules in the bundles, by diffusion and exchange of molecules, in contrast to previous reports which attribute the changes to stochastic conductance switching. The packing density of the SAM around the bundles of inserted molecules influence the fluctuations, as the fluctuations observed at 77 K all take place in bundles inserted at locally less-densely packed SAM areas. At room temperature fluctuations of bundles inserted in well-ordered areas are also observed.     

Vibrational spectra and conformations of 1,4-cyclohexadiene and its oxygen analogues: ab initio and density functional calculations

The vibrational spectra and ring-puckering potential energy functions of 1,4-cyclohexadiene, 4H-pyran and 1,4-dioxin have been examined using a density functional theory (DFT) method as well as the Hartree–Fock (HF) and second-order Møller–Plesset (MP2) methods. The calculated vibrational frequencies and potential energy functions of those molecules have been compared with previously reported experimental data and MM3 results. For all three molecules, the DFT method using Becke's three-parameter functional (B3LYP) has led to the prediction of more accurate vibrational frequencies than the HF and MP2 methods. The enlargement of the basis set at the B3LYP levels has improved the accuracy of calculated vibrational frequencies. In particular, the C–O–C=C torsional force field parameters obtained from the B3LYP method have correctly predicted the ring-puckering potential energy functions of the oxygen-containing analogues, 4H-pyran and 1,4-dioxin, which could not be done by the MM3 method.