Synthesis of Degradable Organic Nanotubes by Bottlebrush Molecular Templating

Kun Huang, Mark Johnson, and Javid Rzayev

http://pubs.acs.org/doi/abs/10.1021/mz3002287

Polymer bottlebrushes were synthesized by a graft from approach by polymerizing polylactide (PLA) from a poly(glycidyl methacrylate) backbone. Then poly(styrene-co-maleic anhydride) was polymerized from PLA by RAFT. Cysteamine was added to functionalize the maleic groups at the shell of the bottlebrush. The researchers funtionalized about 30% of the maleic anhydride, the rest was hydrolyzed to carboxylic acid groups. Oxidation of the thiol to disulfides was used to crosslink the shell of the brush, which was facilitated by I2, THF. Formation of disulfide bonds was confirmed by FTIR. The PLA core was then degraded by hydrolysis under basic conditions, forming hollow nanotube-like assemblies. The shell could be further degraded by reduction with DTT. FTIR, DLS, and TEM was used to help characterize the brushes.

A “Mix-and-Click” Approach to Double Core−Shell Micelle Functionalization

Claire F. Hansell and Rachel K. O’Reilly

http://pubs.acs.org/doi/abs/10.1021/mz300230c

RAFT was used to create a block polymer consisting of a copolymer of styrene and styrene functionalized with  norbornene, followed by a copolymer of triethylene glycol acrylate and trimethylsilane protected propargyl acrylate, which was then deprotected. In water, this polymer self-assembled such that the hydrophobic norbornene block was in the core, and the hydrophilic alkyne block formed the shell. The researchers were able to click on a coumarin functionalized azide to the shell, and a tetrazine to the core. However, if both were added at the same time, functionalization was less efficient (50%), but this was overcome by clicking on the azide coumarin first, followed by the tetrazine (but not the other way around). These particles were studied by TEM, fluorescence spectroscopy, UV-vis, H-NMR, and GPC.

Diffusion ordered spectroscopy (DOSY) as a powerful tool for amphiphilic block copolymer characterization and for critical micelle concentration (CMC) determination

Diffusion ordered spectroscopy (DOSY) as a powerful tool for amphiphilic block copolymer characterization and for critical micelle concentration (CMC) determination

Youssef Bakkour ,  Vincent Darcos ,  Suming Li and Jean Coudane 

 

http://pubs.rsc.org/en/Content/ArticleLanding/2012/PY/c2py20054f?utm_source=toc-alert&utm_medium=email&utm_campaign=pub-py-vol-3-issue-8

 

In this paper, DOSY was used to determine the purity of the block copolymer prepared by ROP of lactide using a difuncitonal PEG as the initiator.   Also, using DOSY, they could determine the critical micelle concentration of their block copolymer.

Direct and highly regioselective and enantioselective allylation of β-diketones

Wesley A. Chalifoux, Samuel K. Reznik & James L. Leighton
http://www.nature.com/nature/journal/v487/n7405/full/nature11189.html?WT.ec_id=NATURE-20120705

In this work, Leighton's allyl-silane reagent is used to do enantioselective allylation of beta-diketones by means of tethering the allylsilane reagent to the enol form of the beta-diketone.

Cancer Prognostics by Direct Detection of p53-Antibodies on Gold Surfaces by Impedance Measurements

Elisabet Prats-Alfonso,* Xavier Sisquella, Nadia Zine, Gemma Gabriel,
Anton Guimerà, F. Javier del Campo, Rosa Villa, Adam H. Eisenberg, Milan Mrksich, Abdelhamid Errachid, Jordi Aguiló, and Fernando Albericio*
 
http://onlinelibrary.wiley.com/doi/10.1002/smll.201102724/abstract

In this paper, impedance measurements of gold contacts functionalized with peptides that specifically bind to the p53 antibody are used to detect the antibody with high selectivity and at low concentrations (down to 10^-17 M).

Well-Defined Nanoclusters as Fluorescent Nanosensors: A Case Study on Au25(SG)18

Well-Defined Nanoclusters as Fluorescent Nanosensors: A Case Study on Au25(SG)18 


Zhikun Wu,* Man Wang, Jiao Yang, Xiaohong Zheng, Weiping Cai, Guowen Meng, Huifeng Qian, Huimin Wang, and Rongchao Jin*

http://onlinelibrary.wiley.com/doi/10.1002/smll.201102590/abstract

In this paper, the authors report the detection of Ag+ ions through fluorescence enhancement of gold nanoclusters.  This response is unique to silver, as other metal cations result in fluorescence quenching.  They also find that depending on the ligand, silver atoms can substitute gold atoms in the nanocluster.  Otherwise, they find that oxidation of the nanoclusters and an undefined interaction between the nanocluster and neutral or cationic silver causes the fluorescence to increase compared to the gold nanocluster itself.

Site-Specific Attachment of a Protein to a Carbon Nanotube End without Loss of Protein Function

http://pubs.acs.org/doi/full/10.1021/bc300131w

Bioconjugate Chemistry

The authors attached calmodulin to the ends of carbon nanotubes and demonstrated that the binding capacity of calmodulin remained unchanged. Protein attachment was done via a site-specific mutation of Tyr80 to azido-tyrosine, which was then coupled to oxidized CNTs using a Staudinger-Bertozzi ligation. Calmodulin binding was demonstrated using an ECFP-calmodulin-binding peptide fusion protein. Treatment with ECFP-CBP showed binding only on the ends of the CNTs.