Elucidating Charge Generation in Green-Solvent Processed Organic Solar Cells

Organic solar cells have the potential to become the cheapest form of electricity. Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors. Next generation photovoltaics based upon environmentally benign “green solvent” processing of organic semiconductors promise a step-change in the adaptability and versatility of solar technologies and promote sustainable development. However, high-performing OSCs are still processed by halogenated (non-environmentally friendly) solvents, so hindering their large-scale manufacture. In this perspective, we discuss the recent progress in developing highly efficient OSCs processed from eco-compatible solvents, and highlight research challenges that should be addressed for the future development of high power conversion efficiencies devices.

Recent Advances on Large-Scale Manufacture of Curcumin and Its Nanoformulation for Cancer Therapeutic Application

Considerable amount of research is going on the role of plant species that exhibit anti-cancer properties. One such plant species is turmeric, which has been used in the human diet for centuries. The main active component/polyphenol in turmeric is curcumin. Recently, curcumin has been considered for cancer therapy. The initial challenge with curcumin is its large-scale production and purification of curcuminoids from turmeric. Most of the strategies are not fully effective due to the involvement of many organic solvents, time consumption, and inadequate separation between similar derivatives and crystal structures. Some of the methods to avoid using organic solvents are explained in this entry. The second challenge is that the isolated curcumin is unstable under various environmental and physiological conditions and degrades easily. Various strategies have been proposed and investigated to improve its aqueous solubility, stability, bioavailability, and potential therapeutic applications. Among them, nanoformulation is utilized to fill the gaps between clinical application and production. This review summarizes recent advances in curcumin's large-scale production and purification protocols, the necessity of nanoformulation, recent patents, and its anti-cancer mechanism. Emphasis is given on applying safe and green-tech methods of nanoformulation, including Mozafari and Heating methods.

Ultra-high sensitivity measurement of DNA sequences with conducting polymer-modified electrodes: mechanism, large-scale manufacture, and prospects for rapid polymerase chain reaction measurement (e-PCR)

At low copy number, sequence detection by polymerase chain reaction (PCR) requires up to 30 cycles (amplification by a factor of 109) to produce a reliably detectable concentration of fluorescently-labelled amplicons. The cycle number and hence detection time is determined by the analytical sensitivity of the detector. Hybridisation of complementary DNA strands to oligonucleotide-modified conducting polymer electrodes yields an increase in the charge transfer resistance for the ferri-ferrocyanide redox couple. Sensors using this technology for e-PCR offer a label-free method with detector sensitivity in the pM range, potentially decreasing the required cycle number from 30 to 10 and offering a much simplified instrument construction. We demonstrate sensors using screen-printed carbon electrodes modified with a conducting polymer formed from a monomer pre-functionalised with complementary oligonucleotide. Off-chip pre-functionalisation of the conducting polymer precursor is a key step towards practical manufacture and the method is potentially a general one for sensors which require a capture probe-functionalised surface. We demonstrate reliable sensitivity of the interfacial resistance change at the pM scale for short (20-mer) sequences and at the aM scale for bacterial lysate, with dynamic range extending to μM scale and response time-scale 5 min. Donnan exclusion of the redox couple from the surface, as previously proposed, seems unlikely as a mechanism for such ultra-high sensitivity. We demonstrate that the most important element in the response at the lowest concentrations is due to variation of an electrical resistance within the polymer film. We develop a mechanism based on repulsion from the solution interface of dopant anions and attraction towards and trapping at the interface of radical cations (polarons) by the charge associated with surface-bound DNA. With results for >160 single-use sensors, we formulate a response model based on percolation within a random resistor network and highlight challenges for large-scale manufacture of such sensors. We propose a PCR device concept for rapid use at point-of-sampling.

Diketopyrrolopyrrole (DPP) pigments

Since their industrial introduction in the 1980s, DPP pigments now constitute a highly important group of high-performance carbonyl pigments. The DPP system was first discovered by accident in 1974, and was subsequently re-investigated by Ciba Geigy who recognized its potential to provide commercial organic pigments. DPP pigments exhibit strong similarities compared with quinacridone pigments, in terms of their molecular and crystal structures and their properties, including low solubility and excellent fastness properties. X-ray crystal structural analysis has demonstrated that their technical performance is the result of intermolecular hydrogen bonding and π–π stacking interactions in the crystal lattice structure. Based on a simple retrosynthetic analysis, an efficient synthetic process was developed by Ciba Geigy for their large-scale manufacture. DPP pigments currently provide orange through to reddish violet shades and have become of special importance in providing brilliant saturated red shades with the outstanding durability required for applications such as automotive paints.

Metachronal waves in magnetic micro-robotic paddles for artificial cilia

Biological cilia generate fluid movement within viscosity-dominated environments using beating motions that break time-reversal symmetry. This creates a metachronal wave, which enhances flow efficiency. Artificially mimicking this behaviour could improve microfluidic point-of-care devices, since viscosity-dominated fluid dynamics impede fluid flow and mixing of reagents, limiting potential for multiplexing diagnostic tests. However, current biomimicry schemes require either variation in the hydrodynamic response across a cilia array or a complex magnetic anisotropy configuration to synchronise the actuation sequence with the driving field. Here, we show that simple modifications to the structural design introduce phase differences between individual actuators, leading to the spontaneous formation of metachronal waves. This generates flow speeds of up to 16 μm/s as far as 675 μm above the actuator plane. By introducing metachronal waves through lithographic structuring, large scale manufacture becomes feasible. Additionally, by demonstrating that metachronal waves emerge from non-uniformity in internal structural mechanics, we offer fresh insight into the mechanics of cilia coordination.

A Flexible Pressure Sensor with Ink Printed Porous Graphene for Continuous Cardiovascular Status Monitoring

Flexible electronics with continuous monitoring ability a extensively preferred in various medical applications. In this work, a flexible pressure sensor based on porous graphene (PG) is proposed for continuous cardiovascular status monitoring. The whole sensor is fabricated in situ by ink printing technology, which grants it the potential for large-scale manufacture. Moreover, to enhance its long-term usage ability, a polyethylene terephthalate/polyethylene vinylacetate (PET/EVA)-laminated film is employed to protect the sensor from unexpected shear forces on the skin surface. The sensor exhibits great sensitivity (53.99/MPa), high resolution (less than 0.3 kPa), wide detecting range (0.3 kPa to 1 MPa), desirable robustness, and excellent repeatability (1000 cycles). With the assistance of the proposed pressure sensor, vital cardiovascular conditions can be accurately monitored, including heart rate, respiration rate, pulse wave velocity, and blood pressure. Compared to other sensors based on self-supporting 2D materials, this sensor can endure more complex environments and has enormous application potential for the medical community.

Plant-Based Vaccines: The Way Ahead?

Severe virus outbreaks are occurring more often and spreading faster and further than ever. Preparedness plans based on lessons learned from past epidemics can guide behavioral and pharmacological interventions to contain and treat emergent diseases. Although conventional biologics production systems can meet the pharmaceutical needs of a community at homeostasis, the COVID-19 pandemic has created an abrupt rise in demand for vaccines and therapeutics that highlight the gaps in this supply chain’s ability to quickly develop and produce biologics in emergency situations given a short lead time. Considering the projected requirements for COVID-19 vaccines and the necessity for expedited large scale manufacture the capabilities of current biologics production systems should be surveyed to determine their applicability to pandemic preparedness. Plant-based biologics production systems have progressed to a state of commercial viability in the past 30 years with the capacity for production of complex, glycosylated, “mammalian compatible” molecules in a system with comparatively low production costs, high scalability, and production flexibility. Continued research drives the expansion of plant virus-based tools for harnessing the full production capacity from the plant biomass in transient systems. Here, we present an overview of vaccine production systems with a focus on plant-based production systems and their potential role as “first responders” in emergency pandemic situations.