Visualizing the Solid–Liquid Interface of Conjugated Copolymer Films Using Fluorescent Liposomes

Single-Component Electroactive Polymer Architectures for Non-Enzymatic Glucose Sensing

Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC-based sensors rely predominantly on the use of composite matrices to enable stimuli-responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non-enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT-PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT-PBA and molecularly imprinted PEDOT-PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non-imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly.

Interactions of Catalytic Enzymes with n-Type Polymers for High-Performance Metabolite Sensors

The tight regulation of the glucose concentration in the body is crucial for balanced physiological function. We developed an electrochemical transistor comprising an n-type conjugated polymer film in contact with a catalytic enzyme for sensitive and selective glucose detection in bodily fluids. Despite the promise of these sensors, the property of the polymer that led to such high performance has remained unknown, with charge transport being the only characteristic under focus. Here, we studied the impact of the polymer chemical structure on film surface properties and enzyme adsorption behavior using a combination of physiochemical characterization methods and correlated our findings with the resulting sensor performance. We developed five n-type polymers bearing the same backbone with side chains differing in polarity and charge. We found that the nature of the side chains modulated the film surface properties, dictating the extent of interactions between the enzyme and the polymer film. Quartz crystal microbalance with dissipation monitoring studies showed that hydrophobic surfaces retained more enzymes in a densely packed arrangement, while hydrophilic surfaces captured fewer enzymes in a flattened conformation. X-ray photoelectron spectroscopy analysis of the surfaces revealed strong interactions of the enzyme with the glycolated side chains of the polymers, which improved for linear side chains compared to those for branched ones. We probed the alterations in the enzyme structure upon adsorption using circular dichroism, which suggested protein denaturation on hydrophobic surfaces. Our study concludes that a negatively charged, smooth, and hydrophilic film surface provides the best environment for enzyme adsorption with desired mass and conformation, maximizing the sensor performance. This knowledge will guide synthetic work aiming to establish close interactions between proteins and electronic materials, which is crucial for developing high-performance enzymatic metabolite biosensors and biocatalytic charge-conversion devices.

Naphthalene diimides: perspectives and promise

In this review, we describe the developments in the field of naphthalene diimides (NDIs) from 2016 to the presentday. NDIs are shown to be an increasingly interesting class of molecules due to their electronic properties, large electron deficient aromatic cores and tendency to self-assemble into functional structures. Almost all NDIs possess high electron affinity, good charge carrier mobility, and excellent thermal and oxidative stability, making them promising candidates for applications in organic electronics, photovoltaic devices, and flexible displays. NDIs have also been extensively studied due to their potential real-world uses across a wide variety of applications including supramolecular chemistry, sensing, host-guest complexes for molecular switching devices, such as catenanes and rotaxanes, ion-channels, catalysis, and medicine and as non-fullerene accepters in solar cells. In recent years, NDI research with respect to supramolecular assemblies and mechanoluminescent properties has also gained considerable traction. Thus, this review will assist a wide range of readers and researchers including chemists, physicists, biologists, medicinal chemists and materials scientists in understanding the scope for development and applicability of NDI dyes in their respective fields through a discussion of the main properties of NDI derivatives and of the status of emerging applications.

Organic Bioelectronics: From Functional Materials to Next-Generation Devices and Power Sources

Conjugated polymers (CPs) possess a unique set of features setting them apart from other materials. These properties make them ideal when interfacing the biological world electronically. Their mixed electronic and ionic conductivity can be used to detect weak biological signals, deliver charged bioactive molecules, and mechanically or electrically stimulate tissues. CPs can be functionalized with various (bio)chemical moieties and blend with other functional materials, with the aim of modulating biological responses or endow specificity toward analytes of interest. They can absorb photons and generate electronic charges that are then used to stimulate cells or produce fuels. These polymers also have catalytic properties allowing them to harvest ambient energy and, along with their high capacitances, are promising materials for next-generation power sources integrated with bioelectronic devices. In this perspective, an overview of the key properties of CPs and examination of operational mechanism of electronic devices that leverage these properties for specific applications in bioelectronics is provided. In addition to discussing the chemical structure-functionality relationships of CPs applied at the biological interface, the development of new chemistries and form factors that would bring forth next-generation sensors, actuators, and their power sources, and, hence, advances in the field of organic bioelectronics is described.

Biofuel powered glucose detection in bodily fluids with an n-type conjugated polymer

A promising class of materials for applications that rely on electron transfer for signal generation are the n-type semiconducting polymers. Here we demonstrate the integration of an n-type conjugated polymer with a redox enzyme for the autonomous detection of glucose and power generation from bodily fluids. The reversible, mediator-free, miniaturized glucose sensor is an enzyme-coupled organic electrochemical transistor with a detection range of six orders of magnitude. This n-type polymer is also used as an anode and paired with a polymeric cathode in an enzymatic fuel cell to convert the chemical energy of glucose and oxygen into electrical power. The all-polymer biofuel cell shows a performance that scales with the glucose content in the solution and a stability that exceeds 30 days. Moreover, at physiologically relevant glucose concentrations and from fluids such as human saliva, it generates enough power to operate an organic electrochemical transistor, thus contributes to the technological advancement of self-powered micrometre-scale sensors and actuators that run on metabolites produced in the body.

Synthesis and characterization of acetyl curcumin-loaded core/shell liposome nanoparticles via an electrospray process for drug delivery, and theranostic applications

Despite substantial advancements in divergent drug delivery systems (DDS), there is still room for novel and innovative nanoparticle-mediated drug delivery methodologies such as core/shell liposomes to deliver drugs in a kinetically controlled manner into the active site without any side effects. Herein, ((1E,6E)-3,5-dioxohepta-1,6-diene-1,7-diyl) bis (2-methoxy-4,1-phenylene) diacetate acetyl curcumin (AC)-loaded poly(lactic-co-glycolic acid) (PLGA) core/shell liposome nanoparticles (ACPCSLNPs) were prepared using an electron spray method under an applied electric field, which facilitated the uniform formation of nano-sized liposome nanoparticles (LNPs). Then, kinetically controlled and sustained drug release profiles were investigated using the as-prepared ACPCSLNPs. Moreover, the inner polymeric core could not only induce the generation of electrostatic interactions between the polymer and drug molecules but could also affect the prominent repulsions between the polar head groups of lipids and the nonpolar drug molecules. As a result, the sustained maximum release of the drug molecules (~48.5%) into the system was observed over a long period (~4 days). Furthermore, cell cytotoxicity studies were conducted in a human cervical cancer cell line (HeLa) and a healthy human dermal fibroblast cell line (HDFa) by employing all AC loaded LNPs along with free drugs. Multicolor cell imaging was also observed in HeLa cells using ACPCSLNPs. Notably, more curcumin was released from the ACPCSLNPs than AC due to the presence of polar group attractions and polar-polar interactions between the lipid head groups and curcumin since curcumin is more soluble than AC in aqueous medium. In addition, the predictions of the release kinetic patterns were also investigated thoroughly using the exponential-based Korsmeyer-Peppas (K-P) and Higuchi models for drug-loaded LNPs and PLGA NPs, respectively.