Conjugation of biologically active proteins to polymeric materials is of great interest in the treatment of cancer and other diseases of protein deficiencies. The conjugation of such biomacromolecules is challenging both due to their hydrophilicity and propensity to denature under non-native conditions. We describe a novel reactive self-assembly approach to “wrap” a protein with polymers, simultaneously protecting its delicate folded state and silencing its enzymatic activity. This approach has been demonstrated using caspase-3, an apoptosis-inducing protein, as the first case study. The protein-polymer conjugation is designed to be reversed under the native conditions for caspase-3, i.e. the reducing environment found in the cytosol. The current strategy allowed release and recovery of up to 86% of caspase activity and nanogel-caspase-3 conjugates induced 70–80% apoptotic cell death shortly thereafter. This approach is widely generalizable and should be applicable to the intracellular delivery of a wide range of therapeutic proteins for treatment of complex and genetic diseases.

An amphiphilic nanoassembly was designed to respond to the concurrent presence of a protein and an enzyme. We present herein a system, where in the presence of these two stimuli causes a supramolecular disassembly and molecular release. This molecular release arises in the form a fluorescence response that has been shown to be specific. We also show that this system can be modified to respond only if light stimulus is also present in addition to the protein and the enzyme. Demonstration of such supramolecular disassembly principles could have wide implications in a variety of biological applications.

A series of oligomers, containing oligo(ethylene glycol) (OEG) moieties, with the same composition of amphiphilic functionalities has been designed, synthesized, and characterized for their temperature sensitive behavior. The non-covalent amphiphilic aggregates, formed from these molecules, influence the temperature sensitivity of these molecules. Moreover, the covalent tethering of the amphiphilic units also has significant influence on their temperature sensitivity. The lower critical solution temperatures (LCST) of these oligomers show increasingly sharp transitions with increasing numbers of OEG functional groups, indicating enhanced cooperativity in dehydration of the OEG moieties when covalently tethered. These molecules were also engineered to be concurrently sensitive to enzymatic reaction and pH. This possibility was investigated using porcine liver esterase as the enzyme, where we show that enzymatic action on the pentamer lowers its temperature sensitivity. The product moiety from the enzymatic reaction renders the amphiphilic oligomer exhibit a pH-dependent temperature sensitivity.

Border Gateway Protocol allows Autonomous Systems (ASs) to apply diverse routing policies for selecting routes and for propagating reachability information to other ASs. Although a significant number of studies have been focused on the Internet topology, little is known about what routing policies network operators employ to configure their networks. In this paper, we infer and characterize routing policies employed in the Internet. We find that routes learned from customers are preferred over those from peers and providers, and those from peers are typically preferred over those from providers. We present an algorithm for inferring and characterizing export policies. We show that ASs announce their prefixes to a selected subset of providers. The main reasons behind the selective announcement are the traffic engineering strategy for controlling incoming traffic. The impact of these routing policies might be significant. For example, many Tier-1 ASs reach their (direct or indirect) customers via their peers instead of customers. Furthermore, the selective announcement routing policies imply that there are much less available paths in the Internet than shown in the AS connectivity graph. We hope that our findings will caution network operators in choosing the selective announcement routing policy for traffic engineering. Finally, we study export policies to peers and find that ASs tend to announce all of their prefixes to other peers. To the best of our knowledge, this is the first study on systematically understanding routing policies applied in the Internet.

Supramolecular assemblies formed by amphiphilic homopolymers with negatively charged groups in the hydrophilic segment have been designed to enable high labeling selectivity towards reactive side chain functional groups in peptides. The negatively-charged interiors of the supramolecular assemblies are found to block the reactivity of protonated amines that would otherwise be reactive in aqueous solution, while maintaining the reactivity of non-protonated amines. Simple changes to the pH of the assemblies’ interiors allow control over the reactivity of different functional groups in a manner that is dependent on the pKa of a given peptide functional group. The labeling studies carried out in positively charged supramolecular assemblies and free buffer solution show that, even when the amine is protonated, labeling selectivity exists only when complementary electrostatic interactions are present, thereby demonstrating the electrostatically controlled nature of these reactions.