Click And Bioorthogonal Chemistry For The Chemical Modification Of Nanomaterials

The goal of this Ph.D. thesis work is the development of novel reactive nanomaterial templates that can be chemically modified in a facile and robust (i.e., formation of covalent bonds) way for the further modification of the nanomaterial’s physical-chemical properties by the reaction partner molecular system. This type of technology was employed to further expand the application of nanomaterials in nanomedicine, chemical biology and materials science. In order to reach this goal, as a proof of concept, small (d = 3nm) gold nanoparticles (AuNPs) and carbon nanotubes (CNT) were used as the nanomaterial substrates. Innovative synthetic strategies for the introduction of click and bioorthogonal functional groups onto the surface of these nanomaterials were developed. These functional groups include a maleimide that can undergo three click reactions with different functional groups (i.e., Michael addition with nucleophiles, Diels-Alder cycloaddition with dienes, dipolar cycloadditions with dipolar molecules), strained alkynes for bioorthogonal strain-promoted cycloaddition reactions with azides and nitrones, and methyl-2-(diphenylphosphino)benzoate moieties for the bioorthogonal Staudinger-Bertozzi ligation with azides. In order to study and characterize these clickable and bioorthogonal nanomaterial templates, methodologies for the determination of the amount of reactive functionalities introduced onto the nanomaterial’s surface and the evaluation of their proper reactivity were also developed. 1H NMR spectroscopy, transmission electron microscopy, and thermogravimetric analysis, were methodically used for the quantification of the interfacial reactive functionalities. 1H NMR spectroscopy was also employed to follow the correct interfacial reactivity of the nanomaterial template. Finally, in collaboration with Surface Science Western, the use of X-ray photoelectron spectroscopy (XPS) was developed as a method to independently confirm all the previously obtained results and, more specifically, quantitate the amount of interfacial reactive molecules that were introduced, track the interfacial organic chemistry of the nanomaterial template, and determine interfacial reaction yields. In all cases the clickable and bioorthogonal nanomaterial templates were found to react quickly, efficiently and chemoselectively with their chemical reporter through a simple pour-and-mix type of chemistry. The utility of these clickable and bioorthogonal nanomaterial templates was finally showcased in bioconjugation, for the synthesis of fluorogenic biosensors, nanomaterial hybrids and nanomaterial-based MRI contrast agents

Evolving Morphologies for Locomoting Micro-scale Robotic Agents

Designing locomotive mechanisms for micro-scale robotic systems could enable new approaches to tackling problems such as transporting cargos, or self-assembling into pre-programmed architectures. Morphological factors often play a crucial role in determining the behaviour of micro-systems, yet understanding how to design these aspects optimally is a challenge. This paper explores how the morphology of a multi-cellular micro-robotic agent can be optimised for reliable locomotion using artificial evolution in a stochastic environment. We begin by establishing the theoretical mechanisms that would allow for collective locomotion to emerge from contractile actuations in multiple connected cells. These principles are used to develop a Cellular Potts model, in order to explore the locomotive performance of morphologies in simulation. Evolved morphologies yield significantly better performance in terms of the reliability of the travel direction and the distance covered, compared to random morphologies. Finally, we demonstrate that patterns in evolved morphologies are robust to small imperfections and generalise well to larger morphologies

Dipole Moment Effect on the Electrochemical Desorption of Self-Assembled Monolayers of 310-Helicogenic Peptides on Gold

AbstractThe front cover artwork is provided by Pierangelo Gobbo and Flavio Maran, University of Padova (Italy). The image highlights how the orientation of the dipole moment associated with helical peptides affects the electrodesorption potential of the corresponding self‐assembled monolayers. Read the full text of the Article at 10.1002/celc.201600573

Spontaneous membrane-less multi-compartmentalisation via aqueous two-phase separation in complex coacervate microdroplets

Polyelectrolyte/nucleotide multiphase complex coacervate droplets are produced by internalized aqueous two-phase separation and used for the spatially dependent chemical transfer of sugar molecules, providing a step towards the development of membrane-free "organelles" within coacervate-based protocells

Colloidosomes as a Protocell Model: Engineering Life-Like Behaviour through Organic Chemistry

The bottom-up synthesis of self-assembled micro-compartmentalised systems that mimic basic characteristics of living cells is rapidly evolving. These types of systems are termed “protocells” and can be chemically programmed to grow and divide, to send and receive chemical signals, to transcript and translate chemical information, to adhere to surfaces or to other protocells, and to perform rudimental enzyme-mediated metabolic processes. An emerging protocell model that is attracting great attention is the colloidosome. Colloidosomes are microcapsules with a chemically crosslinked, semipermeable membrane composed of amphiphilic nanoparticles. Colloidosomes display important advantages over other protocell models (e. g., vesicles and coacervate micro-droplets) due to their physical-chemical properties that can be easily tuned through the careful engineering of their synthetic building blocks. In this review, we deliver an overview of the different types of colloidosomes that have been developed thus far and discuss how organic chemistry contributes to the design and bottom-up synthesis of novel types of colloidosomes endowed with advanced chemically programmed bio-inspired functions

Properties and Curing Kinetics of a Processable Binary Benzoxazine Blend

A benzoxazine system is presented combining liquid cardanol-based benzoxazine (CA-a) and an effective initiator (3,3 '-thiodipropionic acid, TDA) to bisphenol A-based benzoxazine (BA-a). The resultant mixture of monomeric precursors shows excellent fluidity and a relatively low peak polymerization temperature of around 200 degrees C. Moreover, the cured polybenzoxazine displays a high thermal decomposition temperature (T-d,T-5% > 330 degrees C), a moderately high glass transition temperature (similar to 148 degrees C), and robust mechanical strength (storage modulus similar to 2.8 GPa) comparable to those of the polybenzoxazine homopolymer obtained by curing BA-a. A comprehensive investigation into the microstructure and curing kinetics has also been conducted on the system, offering an extensive background for future studies

An Azide-Functionalized Nitronyl Nitroxide Radical: Synthesis, Characterization and Staudinger-Bertozzi Ligation Reactivity

An azide-functionalized nitronyl nitroxide was successfully synthesized and its reactivity towards the Staudinger-Bertozzi ligation was explored. While a model reaction in solution showed the conversion of the nitronyl nitroxide to an imino nitroxide radical, the same reaction at the interface of gold nanoparticles allowed for successful covalent incorporation of the nitronyl nitroxide radical onto the nanoparticles

Orthogonal Light-Dependent Membrane Adhesion Induces Social Self-Sorting and Member-Specific DNA Communication in Synthetic Cell Communities

Developing orthogonal chemical communication pathways in diverse synthetic cell communities is a considerable challenge due to the increased crosstalk and interference associated with large numbers of different types of sender-receiver pairs. Herein, the authors control which sender-receiver pairs communicate in a three-membered community of synthetic cells through red and blue light illumination. Semipermeable protein-polymer-based synthetic cells (proteinosomes) with complementary membrane-attached protein adhesion communicate through single-stranded DNA oligomers and synergistically process biochemical information within a community consisting of one sender and two different receiver populations. Different pairs of red and blue light-responsive protein-protein interactions act as membrane adhesion mediators between the sender and receivers such that they self-assemble and socially self-sort into different multicellular structures under red and blue light. Consequently, distinct sender-receiver pairs come into the signaling range depending on the light illumination and are able to communicate specifically without activation of the other receiver population. Overall, this work shows how photoswitchable membrane adhesion gives rise to different self-sorting protocell patterns that mediate member-specific DNA-based communication in ternary populations of synthetic cells and provides a step towards the design of orthogonal chemical communication networks in diverse communities of synthetic cells