Nanotechnology approaches play an important role in developing novel and efficient carriers for biomedical applications. Peptides are particularly appealing to generate such nanocarriers because they can be rationally designed to serve as building blocks for self-assembling nanoscale structures with great potential as therapeutic or diagnostic delivery vehicles. In this review, we describe peptide-based nanoassemblies and highlight features that make them particularly attractive for the delivery of nucleic acids to host cells or improve the specificity and sensitivity of probes in diagnostic imaging. We outline the current state in the design of peptides and peptide-conjugates and the paradigms of their self-assembly into well-defined nanostructures, as well as the co-assembly of nucleic acids to form less structured nanoparticles. Various recent examples of engineered peptides and peptide-conjugates promoting self-assembly and providing the structures with wanted functionalities are presented. The advantages of peptides are not only their biocompatibility and biodegradability, but the possibility of sheer limitless combinations and modifications of amino acid residues to induce the assembly of modular, multiplexed delivery systems. Moreover, functions that nature encoded in peptides, such as their ability to target molecular recognition sites, can be emulated repeatedly in nanoassemblies. Finally, we present recent examples where self-assembled peptide-based assemblies with “smart” activity are used in vivo. Gene delivery and diagnostic imaging in mouse tumor models exemplify the great potential of peptide nanoassemblies for future clinical applications.

In the past few decades natural and non-natural prolines-and among the latter, a-quaternary derivatives are of great interest-have found wide application in the design of new organocatalysts [1] and chiral auxiliaries [2] for asymmetric synthesis. Furthermore, non-natural proline units have been incorporated in new peptide chains, affording peptidomimetics with different conformational flexibility and correlated drastic changes of their secondary structures. [3] In the best cases, these alterations enhance the resistance of the modified proteins to metabolic and chemical degradation and hence their overall biological activity.A number of strategies [4] -and, among them, those that adopt the well-known Kawabatas principles of "memory of chirality" (MOC) [5] and of "chiral non-racemic enolate" [6] emerge as the most appealing-have been proposed for the stereoselective synthesis of quaternary a-amino acids. In particular, the synthetic methods for quaternary prolines [7] involve the enantioselective functionalization of l-proline derivatives, for example, through self-reproduction of chirality, diastereoselective alkylation, or transfer of stereochemical information via cyclic ammonium ylides.Recently, we reported a straightforward protocol for the enantioselective synthesis of quaternary N-alkyl-a-4-nitrophenyl-a-amino tert-butyl esters, through N-alkylation of the corresponding a-N-(4-nitrophenyl)sulfonamido esters, followed by degradative rearrangement, with loss of SO 2 .[8]The one-pot overall process is highly stereoselective, ees up to 98 %; in contrast, the reaction conducted with the preformed N-alkyl-a-N-(4-nitrophenyl)sulfonamido ester gave the corresponding quaternary amino ester with very low ees, for example, 28 % ee in the case of N-allyl phenylalanine derivative. In the present paper we describe the rearrangement under basic conditions of N-(arylsulfonyl)proline tert-butyl esters 1, which showed a different behavior of that found for N-alkylated open-chain sulfonamido esters. Preliminary runs (Table 1), conducted on N-(4-nitrobenzenesul-[a] F.

To achieve enantioselective electroanalysis either chiral electrodes or chiral media are needed. High enantiodiscrimination properties can be granted by the "inherent chirality" strategy of developing molecular materials in which the stereogenic element responsible for chirality coincides with the molecular portion responsible for their specific properties, an approach recently yielding outstanding performances as electrode surfaces. Inherently chiral ionic liquids (ICILs) have now been prepared starting from atropisomeric 3,3'-bicollidine, synthesized from inexpensive reagents, resolved into antipodes without need of chiral HPLC and converted into long-chain dialkyl salts with melting points below room temperature. Both the new ICILs and shorter family terms, solid at room temperature, employed as low-concentration additives in achiral ILs, afford impressive enantioselection for the enantiomers of different probes on achiral electrodes, regularly increasing with additive concentration.

Janus nanoparticles (JNPs) can offer significant potential for synthesis of multifunctional materials, due to their inherent property contrast between the lobes. Asymmetric surface chemical modifications on JNPs can be performed such that each lobe can carry different surface and/or bulk‐like properties, which could be combined in surprising ways. In this work, it is shown that snowman‐type polymeric JNPs can be used to make conductive materials with tunable resistance and surface polarity. By changing the relative size between a conductive and an electrically insulating lobe, the bulk powder conductivity within a series of JNPs by a factor of 10 without changing the intrinsic conductivity of the polymer can be tuned. In the same time, the surface polarity of the powder material decreased by a factor of 5. The possibility to synthesize multifunctional materials from JNPs building blocks that enable the coupling of a bulk‐like property with a surface functionality is therefore demonstrated.

The 'one-pot' stereoselective conversion of N-(4-nitrobenzene)sulfonyl-alpha-amino acid tert-butyl esters into the corresponding N-alkyl-alpha-(4-nitrophenyl)-alpha-amino esters has been realized through N-alkylation of the starting amido esters, followed by N-C(alpha) migration of the p-nitrophenyl group and the loss of sulfur dioxide; the asymmetric induction is determined by an intermediate non-racemic enolate, without the need of an external source of chirality.