New Functional Handle for Use as a Self-Reporting Contrast and Delivery Agent in Nanomedicine

Fluorescence-readout as a powerful macromolecular characterisation tool

The last few decades have witnessed significant progress in synthetic macromolecular chemistry, which can provide access to diverse macromolecules with varying structural complexities, topology and functionalities, bringing us closer to the aim of controlling soft matter material properties with molecular precision. To reach this goal, the development of advanced analytical techniques, allowing for micro-, molecular level and real-time investigation, is essential. Due to their appealing features, including high sensitivity, large contrast, fast and real-time response, as well as non-invasive characteristics, fluorescence-based techniques have emerged as a powerful tool for macromolecular characterisation to provide detailed information and give new and deep insights beyond those offered by commonly applied analytical methods. Herein, we critically examine how fluorescence phenomena, principles and techniques can be effectively exploited to characterise macromolecules and soft matter materials and to further unravel their constitution, by highlighting representative examples of recent advances across major areas of polymer and materials science, ranging from polymer molecular weight and conversion, architecture, conformation to polymer self-assembly to surfaces, gels and 3D printing. Finally, we discuss the opportunities for fluorescence-readout to further advance the development of macromolecules, leading to the design of polymers and soft matter materials with pre-determined and adaptable properties.

Anion-Dependent Hydrogen-Bond Polarity Switching in Ethylene-bridged Urea Oligomers

The reversible coordination of anions to an N,N'-disubstituted 3,5-bis(trifluoromethyl)phenylurea located at a terminus of a linear chain of ethylene-bridged hydrogen-bonded ureas triggers a cascade of conformational changes. A series of hydrogen-bond polarity reversals propagates along the oligomer, leading to a global switch of its hydrogen-bond directionality. The induced polarity switch, transmitted through four reversible urea groups, results in a change in emission and excitation wavelengths of a fluorophore located at the opposite terminus of the oligomer. The molecule thus behaves as a chemical sensor with a relayed remote spectroscopic response to variations in anion concentration. The polarity switch induced by anion concentration constitutes an artificial communication mechanism for conveying information through oligomeric structures.

Two Birds with One Stone: A Novel Dithiomaleimide-Based GalNAc-siRNA Conjugate Enabling Good siRNA Delivery and Traceability

For the first time, a novel dithiomaleimides (DTM) based tetra-antennary GalNAc conjugate was developed, which enable both efficient siRNA delivery and good traceability, without incorporating extra fluorophores. This conjugate can be readily constructed by three click-type reactions, that is, amidations, thiol-dibromomaleimide addition and copper catalyzed azide-alkyne cycloaddition (CuAAC). And it also has comparable siRNA delivery efficiency, with a GalNAc L96 standard to mTTR target. Additionally, due to the internal DTMs, a highly fluorescent emission was observed, which benefited delivery tracking and reduced the cost and side effects of the extra addition of hydrophobic dye molecules. In all, the simple incorporation of DTMs to the GalNAc conjugate structure has potential in gene therapy and tracking applications.

Chemical design and synthesis of macromolecular profluorescent nitroxide systems as self-reporting probes

The objective of this mini-review article is to highlight the importance of the chemical design towards the synthesis of polymeric profluorescent nitroxides applicable as self-reporting probes.

Precise control over supramolecular nanostructures via manipulation of H-bonding in π-amphiphiles

Self-assembled supramolecular architectures are ubiquitous in nature. A synchronized combination of dynamic noncovalent interactions is the major driving force in forming unique structures with high-precision control over the self-assembly of supramolecular materials. Herein, we have achieved programmable nanostructures by introducing single/multiple H-bonding units in a supramolecular building block. A diverse range of nanostructures can be generated in aqueous medium by subtly tuning the structure of π-amphiphiles. 1D-cylindrical micelles, 2D-nanoribbons and hollow nanotubes are produced by systematically varying the number of H-bonding units (0-2) in structurally near identical π-amphiphiles. Spectroscopic measurements revealed the decisive role of H-bonding units for different modes of molecular packing. We have demonstrated that a competitive self-assembled state (a kinetically controlled aggregation state and a thermodynamically controlled aggregation state) can be generated by fine tuning the number of noncovalent forces present in the supramolecular building blocks. The luminescence properties of conjugated dithiomaleimide (DTM) provided insight into the relative hydrophobicity of the core in these nanostructures. In addition, fluorescence turn-off in the presence of thiophenol enabled us to probe the accessibility of the hydrophobic core in these assembled systems toward guest molecules. Therefore the DTM group provides an efficient tool to determine the relative hydrophobicity and accessibility of the core of various nanostructures which is very rarely studied in supramolecular assemblies.

A molecular communication channel consisting of a single reversible chain of hydrogen bonds in a conformationally flexible oligomer

Communication of information through the global switching of conformation in synthetic molecules has hitherto entailed the inversion of chirality. Here, we report a class of oligomer through which information may be communicated through a global reversal of polarity. Ethylene-bridged oligoureas are constitutionally symmetrical, conformationally flexible molecules organized by a single chain of hydrogen bonds running the full length of the oligomer. NMR reveals that this hydrogen-bonded chain may undergo a coherent reversal of directionality. The directional uniformity of the hydrogen-bond chain allows it to act as a channel for the spatial communication of information on a molecular scale. A binding site at the terminus of an oligomer detects local information about changes in pH or anion concentration and transmits that information—in the form of a directionality switch in the hydrogen-bond chain—to a remote polarity-sensitive fluorophore. This propagation of polarity-encoded information provides a new mechanism for molecular communication.

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Simple urea oligomers organize themselves with a single coherent hydrogen-bond chain

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Reversing the polarity of the hydrogen bonding sends a message through the molecule

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Conformational messages can be transmitted by changes in pH or by anion binding

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Receipt of the conformational message is indicated by a remote fluorescent response

Despite the progress made by synthetic chemistry in building the molecular structures of nature, there are still domains of molecular science where biology is immensely more sophisticated than even the most advanced artificial chemical systems. One of these is the ability to use molecular structures to encode and communicate information. Nature stores information in the hydrogen-bond polarity of the base pairs and translates it into molecular function using the polarity matching of these bonds. Here, we outline an early step toward replicating this ability in the design, synthesis, and operation of a series of synthetic molecular devices that employ a structurally simple family of oligomeric molecules that can communicate information in the form of hydrogen-bond polarity. This study marks a significant step in the design of molecular systems that manipulate information, which will form the basis of the many compartmentalization-based nanotechnologies of the future.

Rigidochromism by imide functionalisation of an aminomaleimide fluorophore

Fluorescent dyes that exhibit high solid state quantum yields and sensitivity to the mechanical properties of their local environment are useful for a wide variety of applications, but are limited in chemical diversity. We report a trityl-functionalised maleimide that displays rigidochromic behaviour, becoming highly fluorescent when immobilised in a solid matrix, while displaying negligible fluorescence in solution. Furthermore, the dye's quantum yield is shown to be sensitive to the nature of the surrounding matrix. Computational studies reveal that this behaviour arises from the precise tuning of inter- and intramolecular noncovalent interactions. This work expands the diversity of molecules exhibiting solid state environment sensitivity, and provides important fundamental insights into their design.

Prevent or Cure-The Unprecedented Need for Self-Reporting Materials

Self-reporting smart materials are highly relevant in modern soft matter materials science, as they allow for the autonomous detection of changes in synthetic polymers, materials, and composites. Despite critical advantages of such materials, for example, prolonged lifetime or prevention of disastrous material failures, they have gained much less attention than self-healing materials. However, as diagnosis is critical for any therapy, it is of the utmost importance to report the existence of system changes and their exact location to prevent them from spreading. Thus, we herein critically review the chemistry of self-reporting soft matter materials systems and highlight how current challenges and limitations may be overcome by successfully transferring self-reporting research concepts from the laboratory to the real world. Especially in the space of diagnostic self-reporting systems, the recent SARS-CoV-2 (COVID-19) pandemic indicates an urgent need for such concepts that may be able to detect the presence of viruses or bacteria on and within materials in a self-reporting fashion.

Clusteroluminescence from Cluster Excitons in Small Heterocyclics Free of Aromatic Rings

The study of nonconventional luminescence is important for revealing the luminescence of natural systems and has gradually drawn the attention of researchers in recent years. However, the underlying mechanism is still inexplicable. Herein, the luminescence behavior of two series of simple, heteroatom-containing small molecules without aromatic rings, i.e., maleimide and succinimide derivatives, are studied to gain further mechanistic insight into the nonconventional luminescence process. It has been unveiled that all the molecules exhibit bright and visible luminescence in concentrated solution and solid state and the formation of clusters is the root cause for such behaviors, which can effectively increase the possibility of both the nonradiative n-π* and favorable π-π* transitions and stabilize the excitons formed in the excited state. The distinctive luminescent phenomena and intriguing mechanism presented in this work will be significant for understanding the mechanism of clusteroluminescence and provide new strategies for the rational design of novel luminescent materials.

Rational Construction of a Mitochondrial Targeting, Fluorescent Self-Reporting Drug-Delivery Platform for Combined Enhancement of Endogenous ROS Responsiveness

To maximize the utilization and response to the high oxidative stress environment of tumor sites while avoiding the dilemma of enhancing reactive oxygen species (ROS) response in a single way, mitochondrial targeting combined with fluorescent self-reporting polymeric nanocarriers (1K-TPP and 2K-TPP) with grafted structures were synthesized via a chemoenzymatic method in a high yield to simultaneously enhance the drug delivery of endogenous ROS responses. 1K-TPP and 2K-TPP loaded doxorubicin (DOX) at a high content over 12% and formed homogeneous spherical micelles. In vitro, both of them showed promising high sensitivity (detection limit below 200 nM H₂O₂), fast response, and ratiometric fluorescent self-reporting properties (fluorescent enhancement more than 200 times) to ROS and excellent stability under physiological conditions, while achieving a rapid release of the DOX in response to 1 mM H₂O₂. Cell co-localization experiments exhibited that they had favorable mitochondrial targeting, and mitochondrial isolation experiments also confirmed that the TPP-modified 1K-TPP selectively accumulated nearly three times in mitochondria than that in total cells. The internalization of 1K-TPP and 2K-TPP into cancer cells was greatly improved by nearly 200% compared to that of unmodified control (1K-OH and 2K-OH) and also explored a unique energy-dependent endocytosis. Furthermore, stimulation of endogenous ROS enhanced the green fluorescence intensity (up to 51.4%) of the linked probe so as to destroy the internal structure of the nanocarriers, achieving self-reporting of the drug's intracellular release and tracking of the intracellular location of nanocarriers. The cytotoxicity of DOX-loaded 1K-TPP and 2K-TPP in tumor cells with a higher ROS content showed statistical superiority to that of 1K-OH and 2K-OH, benefiting from the extremely good endogenous ROS response sensitivity leading to the differential selective release of drugs. These results demonstrate the potential of 1K-TPP and 2K-TPP, especially for 1K-TPP, as mitochondria-targeted, fluorescent self-reporting nanocarriers for combined enhancement of endogenous ROS responsiveness.

Manipulating the fluorescence lifetime at the sub-cellular scale via photo-switchable barcoding

Fluorescent barcoding is a pivotal technique for the investigation of the microscale world, from information storage to the monitoring of dynamic biochemical processes. Using fluorescence lifetime as the readout modality offers more reproducible and quantitative outputs compared to conventional fluorescent barcoding, being independent of sample concentration and measurement methods. However, the use of fluorescence lifetime in this area has been limited by the lack of strategies that provide spatiotemporal manipulation of the coding process. In this study, we design a two-component photo-switchable nanogel that exhibits variable fluorescence lifetime upon photoisomerization-induced energy transfer processes through light irradiation. This remotely manipulated fluorescence lifetime property could be visually mapped using fluorescence lifetime imaging microscopy (FLIM), allowing selective storage and display of information at the microscale. Most importantly, the reversibility of this system further provides a strategy for minimizing the background influence in fluorescence lifetime imaging of live cells and sub-cellular organelles.

A programmable chemical switch based on triggerable Michael acceptors

Developing an engineerable chemical reaction that is triggerable for simultaneous chemical bond formation and cleavage by external cues offers tunability and orthogonality which is highly desired in many biological and materials applications. Here, we present a chemical switch that concurrently captures these features in response to chemically and biologically abundant and important cues, viz., thiols and amines. This thiol/amine-triggerable chemical switch is based on a Triggerable Michael Acceptor (TMAc) which bears good leaving groups at its β-position. The acceptor undergoes a "trigger-to-release" process where thiol/amine addition triggers cascaded release of leaving groups and generates a less activated acceptor. The newly generated TMAc can be further reversed to liberate the original thiol/amine by a second nucleophile trigger through a "trigger-to-reverse" process. Within the small molecular volume of the switch, we have shown five locations that can be engineered to achieve tunable "trigger-to-release" kinetics and tailored reversibility. The potential of the engineerable bonding/debonding capability of the chemical switch is demonstrated by applications in cysteine-selective and reversible protein modification, universal self-immolative linkers, and orthogonally addressable hydrogels.

Tuning H2S Release by Controlling Mobility in a Micelle Core

Drug delivery from polymer micelles has been widely studied, but methods to precisely tune rates of drug release from micelles are limited. Here, the mobility of hydrophobic micelle cores was varied to tune the rate at which a covalently bound drug was released. This concept was applied to cysteine-triggered release of hydrogen sulfide (H2S), a signaling gas with therapeutic potential. In this system, thiol-triggered H2S donor molecules were covalently linked to the hydrophobic blocks of self-assembled polymer amphiphiles. Because release of H2S is triggered by cysteine, diffusion of cysteine into the hydrophobic micelle core was hypothesized to control the rate of release. We confirmed this hypothesis by carrying out release experiments from H2S-releasing micelles in varying compositions of EtOH/H2O. Higher EtOH concentrations caused the micelles to swell, facilitating diffusion in and out of their hydrophobic cores and leading to faster H2S release from the micelles. To achieve a similar effect without addition of organic solvent, we prepared micelles with varying core mobility via incorporation of a plasticizing co-monomer in the core-forming block. The glass transition temperature (Tg) of the core block could therefore be precisely varied by changing the amount of the plasticizing co-monomer in the polymer. In aqueous solution under identical conditions, the release rate of H2S varied over 20-fold (t½ = 0.18 - 4.2 h), with the lowest Tg hydrophobic block resulting in the fastest H2S release. This method of modulating release kinetics from polymer micelles by tuning core mobility may be applicable to many types of physically encapsulated and covalently linked small molecules in a variety of drug delivery systems.

Spindle-like and telophase-like self-assemblies mediated by complementary nucleobase molecular recognition

Supramolecular nanoparticles based on complementary nucleobase interactions have aroused wide interest.

Mechanochemical Fluorescence Switching in Polymers Containing Dithiomaleimide Moieties

Polymers that display useful mechanochemical responses, such as changes of their fluorescence characteristics, are attracting great interest. Here, we introduce the fluorescent dithiomaleimide (DTM) motif as a mechanofluorophore and report the mechanoresponse of two polymer types containing this motif. Poly(methyl acrylate) (PMA) and poly(ε-caprolactone)s (PCL) featuring one DTM moiety in the center of each chain (PMA-DTM and PCL-DTM) were synthesized by controlled radical and coordination-insertion ring-opening polymerizations using bifunctional DTM-containing initiators. Upon ultrasonic treatment of PMA-DTM or PCL-DTM of sufficiently high initial molecular weight, both the molecular weight and the fluorescence intensity decreased with similar kinetics, while no significant fluorescence changes were observed for DTM-free reference polymers. The results show that the DTM motif can serve as a mechanophore that displays a mechanically induced fluorescence turn-off.

Emerging Applications of Fluorogenic and Non-fluorogenic Bifunctional Linkers

Homo- and hetero-bifunctional linkers play vital roles in constructing a variety of functional systems, ranging from protein bioconjugates with drugs and functional agents, to surface modification of nanoparticles and living cells, and to the cyclization/dimerization of synthetic polymers and biomolecules. Conventional approaches for assaying conjugation extents typically rely on ex situ techniques, such as mass spectrometry, gel electrophoresis, and size-exclusion chromatography. If the conjugation process involving bifunctional linkers was rendered fluorogenic, then in situ monitoring, quantification, and optical tracking/visualization of relevant processes would be achieved. In this review, conventional non-fluorogenic linkers are first discussed. Then the focus is on the evolution and emerging applications of fluorogenic bifunctional linkers, which are categorized into hetero-bifunctional single-caging fluorogenic linkers, homo-bifunctional double-caging fluorogenic linkers, and hetero-bifunctional double-caging fluorogenic linkers. In addition, stimuli-cleavable bifunctional linkers designed for both conjugation and subsequent site-specific triggered release are also summarized.

Rational design of substituted maleimide dyes with tunable fluorescence and solvafluorochromism

A series of maleimide derivatives were systematically designed and synthesized with tunable fluorescent properties. The facile modifications herein provide a simple methodology to expand the scope of maleimide-based dyes and also provide insight into the relationship between substitution pattern and optical properties.

Supramolecular Nanomedicine Constructed from Cucurbit[8]uril-Based Amphiphilic Brush Copolymer for Cancer Therapy

An amphiphilic supramolecular brush copolymer CB[8]⊃(PEG-Np·PTPE) was constructed on the basis of a novel host-guest molecular recognition model formed by cucurbit[8]uril (CB[8]), 4,4'-bipyridinium derivative, and PEGylated naphthol (PEG-Np). In aqueous solution, the resultant supramolecular brush copolymer self-assembled into supramolecular nanoparticles (SNPs), by which the anticancer drug doxorubicin (DOX) was encapsulated in the hydrophobic core, establishing an artful Förster resonance energy transfer system with dual fluorescence quenched. With the help of intracellular reducing agents and low pH environment, the SNPs disassembled and the loaded drug molecules were released, realizing in situ visualization of the drug release via the location and magnitude of the energy transfer-dependent fluorescence variation. The cytotoxicity evaluation indicated DOX-loaded SNPs effectively inhibited cell proliferation against HeLa cells. Animal experiments demonstrated that these DOX-loaded SNPs highly accumulated in tumor tissues through the enhanced permeability and retention effect and also had a long blood circulation time. These multifunctional supramolecular nanoparticles possessing self-imaging and controllable drug release ability exhibited great potential in cancer therapy.

Reversibly Manipulating the Surface Chemistry of Polymeric Nanostructures via a "Grafting To" Approach Mediated by Nucleobase Interactions

"Grafting to" polymeric nanostructures or surfaces is a simple and versatile approach to achieve functionalization. Herein, we describe the formation of mixed polymer-grafted nanoparticles through a supramolecular "grafting to" method that exploits multiple hydrogen-bonding interactions between the thymine (T)-containing cores of preformed micelles and the complementary nucleobase adenine (A) of added diblock copolymers. To demonstrate this new "grafting to" approach, mixed-corona polymeric nanoparticles with different sizes were prepared by the addition of a series of complementary diblock copolymers containing thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) to a preformed micelle with a different coronal forming block, poly(4-acryloylmorpholine) (PNAM). PNIPAM chains were distributed throughout the corona and facilitated a fast and fully reversible size change of the resulting mixed-corona micelles upon heating. Through the introduction of an environmentally sensitive fluorophore, the reversible changes in nanoparticle size and coronal composition could be easily probed. Furthermore, preparation of mixed-corona micelles also enabled ligands, such as d-mannose, to be concealed and displayed on the micelle surface. This supramolecular "grafting to" approach provides a straightforward route to fabricate highly functionalized mixed polymeric nanostructures or surfaces with potential applications in targeted diagnosis or therapy and responsive surfaces.

Reduction-responsive dithiomaleimide-based polymeric micelles for controlled anti-cancer drug delivery and bioimaging

The biocompatible amphiphilic block copolymers and the CPT model drug were self-assembled into micelles with bright fluorescence and taken up by tumor cells. Then, the disulfide bonds in the micelles were cleaved to release CPT at a high GSH concentration.

Reversible surface functionalisation of emulsion-templated porous polymers using dithiophenol maleimide functional macromolecules

Reversible, easy-to-monitor approach to the surface functionalisation of thiol–acrylate polyHIPEs that can be utilised in a wide range of applications.

Spin fluorescence silencing enables an efficient thermally driven self-reporting polymer release system

A self-reporting profluorescent release system driven by the thermo-reversible dynamic covalent ligation of chromophores to polymer chain, whose fluorescence is silenced by unpaired spins of nitroxides prior to release is introduced.

Anticancer Drug Disulfiram for In Situ RAFT Polymerization: Controlled Polymerization, Multifacet Self-Assembly, and Efficient Drug Delivery

Here we report the synthesis of a well-defined amphiphilic conjugate, tetraethylthiuram disulfide (disulfiram, DS)-poly(ethylene glycol) methyl ether acrylate (DS-PEGMEA), and its multifacet self-assembly in aqueous solutions and application in DS drug delivery to melanoma cells. The DS-PEGMEA was synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization utilizing DS, a 90 year old anticancer drug, as a precursor to generate RAFT agent in situ. Results demonstrate that the in situ formed RAFT can effectively control the polymerization of PEGMEA. Depending on the concentration in aqueous solution, the amphiphilic DS-PEGMEA conjugate can self-assemble to form layered, toroidal, hairy, or spherical nanostructures, respectively. Moreover, DS drug can be further encapsulated by DS-PEGMEA to formulate core-shell structured DS/DS-PEGMEA nanoparticles mediating the apoptosis of melanoma cells (A375) while inducing minimal cytotoxicity to normal (hADSC and NIH fibroblast) cells. Both DS and PEGMEA are approved by the American Food and Drug Administration (FDA); therefore, the DS-PEGMEA has great potential for application in clinical drug delivery to melanoma.

Fluorescent polymeric nanovehicles for neural stem cell modulation

Nanomaterials are emerging as strong candidates for applications in drug delivery and offer an alternative platform to modulate the differentiation and activity of neural stem cells. Herein we report the synthesis and characterization of two different classes of polymeric nanoparticles: N-isopropylacrylamide-based thermoresponsive nanogels RM1 and P(TEGA)-b-P(_d,lLA)₂ nano-micelles RM2. We covalently linked the nanoparticles with fluorescent tags and demonstrate their ability to be internalized and tracked in neural stem cells from the postnatal subventricular zone, without affecting their proliferation, multipotency and differentiation characteristics up to 150 μg ml^-1. The difference in chemical structure of RM1 and RM2 does not appear to impact toxicity however it influences the loading capacity. Nanogels RM1 loaded with retinoic acid improve solubility of the drug which is released at 37 °C, resulting in an increase in the number of neurons, comparable to what can be obtained with a solution of the free drug solubilised with a small percentage of DMSO.

Aminomaleimide fluorophores: a simple functional group with bright, solvent dependent emission

Amino-substituted maleimides form a new class of highly emissive compounds, with large Stokes shifts (>100 nm) and high quantum yields (up to ∼60%).

Amino-substituted maleimides form a new class of highly emissive compounds, with large Stokes shifts (>100 nm) and high quantum yields (up to ∼60%). Emission is responsive to the maleimide's environment with both a red-shift, and quenching, observed in protic polar solvents. Aminomaleimides are easily functionalised, providing a versatile fluorescent probe.

Fluorescent Block Copolymer Micelles That Can Self-Report on Their Assembly and Small Molecule Encapsulation

Block copolymer micelles have been prepared with a dithiomaleimide (DTM) fluorophore located in either the core or shell. Poly(triethylene glycol acrylate)-b-poly(tert-butyl acrylate) (P(TEGA)-b-P(tBA)) was synthesized by RAFT polymerization, with a DTM-functional acrylate monomer copolymerized into either the core forming P(tBA) block or the shell forming P(TEGA) block. Self-assembly by direct dissolution afforded spherical micelles with R_h of ca. 35 nm. Core-labeled micelles (CLMs) displayed bright emission (Φ_f = 17%) due to good protection of the fluorophore, whereas shell-labeled micelles (SLMs) had lower efficiency emission due to collisional quenching in the solvated corona. The transition from micelles to polymer unimers upon dilution could be detected by measuring the emission intensity of the solutions. For the core-labeled micelles, the fluorescence lifetime was also responsive to the supramolecular state, the lifetime being significantly longer for the micelles (τ_Av,I = 19 ns) than for the polymer unimers (τ_Av,I = 9 ns). The core-labeled micelles could also self-report on the presence of a fluorescent hydrophobic guest molecule (Nile Red) as a result of Förster resonance energy transfer (FRET) between the DTM fluorophore and the guest. The sensitivity of the DTM fluorophore to its environment therefore provides a simple handle to obtain detailed structural information for the labeled polymer micelles. A case will also be made for the application superiority of core-labeled micelles over shell-labeled micelles for the DTM fluorophore.

Redox tunable delivery systems: sweet block copolymer micelles via thiol–(bromo)maleimide conjugation

A tunable release of encapsulated Nile Red from xyloglucan-oligosaccharides-block-polycaprolactone obtained by thiol–(bromo)maleimide click reaction was successfully achieved by mixing their Gluathione-responsiveness.

CO2/pH-responsive particles with built-in fluorescence read-out

A novel fluorescent monomer was synthesized to probe the state of CO₂-responsive cross-linked polymer particles.

Unexpected fluorescence from polymers containing dithio/amino-succinimides

Nonfluorescent succinimides become fluorescent only by thiol and amine group substitutions, without employing any fluorescent units.

Methods to Make Homogenous Antibody Drug Conjugates

Antibody drug conjugates (ADCs) have progressed from hypothesis to approved therapeutics in less than 30 years, and the technologies available to modify both the antibodies and the cytotoxic drugs are expanding rapidly. For reasons well reviewed previously, the field is trending strongly toward homogeneous, defined antibody conjugation. In this review we present the antibody and small molecule chemistries that are currently used and being explored to develop specific, homogenous ADCs.

Poly(ferulic acid-co-tyrosine): Effect of the Regiochemistry on the Photophysical and Physical Properties en Route to Biomedical Applications

The photophysical and mechanical properties of novel poly(carbonate-amide)s derived from two biorenewable resources, ferulic acid (FA) and l-tyrosine ethyl ester, were evaluated in detail. From these two bio-based precursors, a series of four monomers were generated (having amide and/or carbonate coupling units with remaining functionalities to allow for carbonate formation) and transformed to a series of four poly(carbonate-amide)s. The simplest monomer, which was biphenolic and was obtained in a single amidation synthetic step, displayed bright, visible fluorescence that was twice brighter than FA. Multidimensional fluorescence spectroscopy of the polymers in solution highlighted the strong influence that regioselectivity and the degree of polymerization have on their photophysical properties. The regiochemistry of the system had little effect on the wettability, surface free energy, and Young’s modulus (ca. 2.5 GPa) in the solid state. Confocal imaging of solvent-cast films of each polymer revealed microscopically flat surfaces with fluorescent emission deep into the visible region. Fortuitously, one of the two regiorandom polymers (obtainable from the biphenolic monomer in only an overall two synthetic steps from FA and l-tyrosine ethyl ester) displayed the most promising fluorescent properties both in the solid state and in solution, allowing for the possibility of translating this system as a self-reporting or imaging agent in future applications. To further evaluate the potential of this polymer as a biodegradable material, hydrolytic degradation studies at different pH values and temperatures were investigated. Additionally, the antioxidant properties of the degradation products of this polymer were compared with its biphenolic monomer and FA.

Construction of a versatile and functional nanoparticle platform derived from a helical diblock copolypeptide-based biomimetic polymer

Sequential polymerization of N-carboxyanhydrides accelerated by nitrogen flow is utilized to generate a novel well-defined diblock copolypeptide (PDI = 1.08), with incorporation of alkyne-functionalized side-chain groups allowing for rapid and efficient thiol-yne click-type modifications, followed by self-assembly into nanopure water to construct a helical polypeptide-based versatile and functional nanoparticle platform.

Colour-tunable fluorescent multiblock micelles

Emerging strategies based on the self-assembly of block copolymers have recently enabled the bottom-up fabrication of nanostructured materials with spatially distinct functional regions. Concurrently, a drive for further miniaturization in applications such as optics, electronics and diagnostic technology has led to intense interest in nanomaterials with well-defined patterns of emission colour. Using a series of fluorescent block copolymers and the crystallization-driven living self-assembly approach, we herein describe the synthesis of multicompartment micelles in which the emission of each segment can be controlled to produce colours throughout the visible spectrum. This represents a bottom-up synthetic route to objects analogous to nanoscale pixels, into which complex patterns may be written. Because of their small size and high density of encoded information, these findings could lead to the development of new materials for applications in, for example, biological diagnostics, miniaturized display technology and the preparation of encoded nanomaterials with high data density.

Dual effect of thiol addition on fluorescent polymeric micelles: ON-to-OFF emissive switch and morphology transition

Reaction with a thiol causes solution-state self-assembled block copolymer nanoparticles to undergo a simultaneous morphology transition from micelles to vesicles coupled to an ON-to-OFF switch in particle fluorescence.