A bioinspired cercosporin/polymethylmethacrylate photocatalyst with high efficiency for decontamination of pharmaceuticals and pathogens

Synthetic Biology-based Construction of Unnatural Perylenequinones with Improved Photodynamic Anticancer Activities

The construction of structural complexity and diversity of natural products is crucial for drug discovery and development. To overcome high dark toxicity and poor photostability of natural photosensitizer perylenequinones (PQs) for photodynamic therapy, herein, we aim to introduce the structural complexity and diversity to biosynthesize the desired unnatural PQs in fungus Cercospora through synthetic biology-based strategy. Thus, we first elucidate the intricate biosynthetic pathways of class B PQs and reveal how the branching enzymes create their structural complexity and diversity from a common ancestor. This enables the rational reprogramming of cercosporin biosynthetic pathway in Cercospora to generate diverse unnatural PQs without chemical modification. Among them, unnatural cercosporin A displays remarkably low dark toxicity and high photostability with retention of great photodynamic anticancer and antimicrobial activities. Moreover, it is found that, unlike cercosporin, unnatural cercosporin A could be selectively accumulated in cancer cells, providing potential targets for drug development. Therefore, this work provides a comprehensive foundation for preparing unnatural products with customized functions through synthetic biology-based strategies, thus facilitating drug discovery pipelines from nature.

Bio-based matrix photocatalysts for photodegradation of antibiotics

Antibiotics development during the last century permitted unprecedent medical advances. However, it is undeniable that there has been an abuse and misuse of antimicrobials in medicine and cosmetics, food production and food processing, in the last decades. The pay toll for human development and consumism is the emergence of extended antimicrobial resistance and omnipresent contamination of the biosphere. The One Health concept recognizes the interconnection of human, environmental and animal health, being impossible alter one without affecting the others. In this context, antibiotic decontamination from water-sources is of upmost importance, with new and more efficient strategies needed. In this framework, light-driven antibiotic degradation has gained interest in the last few years, strongly relying in semiconductor photocatalysts. To improve the semiconductor properties (i.e., efficiency, recovery, bandgap width, dispersibility, wavelength excitation, etc.), bio-based supporting material as photocatalysts matrices have been thoroughly studied, exploring synergetic effects as operating parameters that could improve the photodegradation of antibiotics. The present work describes some of the most relevant advances of the last 5 years on photodegradation of antibiotics and other antimicrobial molecules. It presents the conjugation of semiconductor photocatalysts to different organic scaffolds (biochar and biopolymers), then to describe hybrid systems based on g-C3N4 and finally addressing the emerging use of organic photocatalysts. These systems were developed for the degradation of several antibiotics and antimicrobials, and tested under different conditions, which are analyzed and thoroughly discussed along the work.

Designing a cercosporin-bioinspired bifunctional algicide with flocculation and photocatalysis for efficiently controlling harmful cyanobacterial blooms

Harmful cyanobacterial blooms (HCBs) are spreading in freshwater ecosystems worldwide, adversely affecting drinking water supplies, aquatic production, recreational and tourism activities. Therefore, the efficient and environmentally friendly method is still of interest to be developed to effectively control HCBs. Inspired by the excellent algicidal activity of cercosporin (CP), a novel metal-free algaecide SiO2@EDU@CP (EDU, N-ethyl-N'-(3-dimethylaminopropyl)urea) with flocculation and photoremoval functions, was successfully designed and prepared in one-step to simultaneously introduce CP and EDU on SiO2 nanoparticles. It could rapidly form algae flocs in 20 min with 97.1% flocculation rate, and remove Microcystis aeruginosa within 12 h with 91.0% algicidal rate under 23 W compact fluorescent light irradiation without any leaked CP detected. Additionally, odorant β-cyclocitral and toxin microcystin-LR were both photodegraded after treatment of SiO2@EDU@CP. Further mechanistic studies showed that the introduction of EDU significantly reversed the zeta potential of SiO2-COOH to achieve the flocculation through neutral charge, and the photophysical characterization of SiO2@EDU@CP revealed the improved charge separation ability to generate reactive oxygen species. More importantly, the utility of SiO2@EDU@CP was well demonstrated by its effectiveness for algae from Taihu Lake under natural sunlight and inability to regrow after treatment. This study not only establishes a bifunctional algicide SiO2@EDU@CP to efficiently control HCBs, but also provides design possibilities to develop more novel and efficient algicides for the better control of practical HCBs.

A theoretical protocol for the rational design of the bioinspired multifunctional hybrid material MIP@cercosporin

CONTEXT

Rational design of polymeric materials prepared with the molecular imprinting technology is gaining even more space, as it can provide the optimal conditions to direct the laboratory molecularly imprinting polymer (MIP) preparation, maximizing their efficiency while reducing costs and preparation time, when compared to try-and-error approaches. We perform a rational design of an MIP with specific cavities for cercosporin accommodation by means of computational tools. The main steps of an MIP preparation were simulated and it was found that the most appropriated functional monomer to be used in the MIP preparation for cercosporin is the acrylamide, while the most suitable crosslinking agent is found to be p-divinylbenzene. Also, the most suitable solvents to remove cercosporin from the cavity are those with low dielectric constant, such as chloroform. This kind of solvent can then be used in washing step, in the case of use the MIP for sensing destinations. On the other hand, solvents like water, which has high dielectric constants, can efficiently improve the interactions between cercosporin and the functional monomer acrylamide, being indicated when the objective is to attract or maintain the cercosporin inside the MIP cavity. Thus, a MIP@cercosporin hybrid material can be used in aqueous solutions more reliably, or even the cercosporin detection in this media can be favoured. In the selectivity analysis of the material prepared in this specific condition, the results point that this MIP can also detect elsinochrome A with high efficiency, and could be more selective for hypericin, altertoxin, hypocrelin A, and phleichrome mycotoxins.

METHOD

The main steps of a MIP synthesis were theoretically simulated trough density functional theory (DFT) calculations aiming to direct and optimize the synthesis and applications of the material before the bench tests. Initially, in order to choose the most suitable functional to be employed for cercosporin calculations, eight of the DFT functionals that had been previously used for cercosporin calculations in literature were tested, which were the LCWPBE, B3LYP, CAM-B3LYP, M062-X, mPW1PW91, PBE0, TPSSh, and ωb97Xd. The theoretical 1H NMR chemical shifts for cercosporin molecule were calculated and compared with experimental results to analyze the performance of the functionals. Of all these, the best results were obtained with the TPSSh functional, employing the 6-31G(d,p) basis set, and this level of theory was then used for all the following steps. All the simulations were performed by means of geometry optimizations and frequency calculations. Additionally, AIM calculations were employed for further analysis of the interactions between the chosen functional monomer and cercosporin template in step 1, which was functional monomer selection. In washing step, the calculations were done using implicit solvation model, and finally, in selectivity tests, the putative "solid" MIP was simulated by freezing the positions of the monomers after the template remotion, and then other structurally similar toxins were placed in its cavity for the geometry optimizations and frequency calculations.

Highly efficient degradation of ofloxacin and diclofenac by composite photocatalyst aloe-emodin/PMMA

Photocatalysis is one of the most effective methods to remove pollutants from water. Photocatalyst is the core of photocatalysis. The composite photocatalyst combines the photosensitizer with the support and uses the photosensitivity of the photosensitizer and the stability and adsorption of the support to achieve efficient and rapid degradation of pharmaceuticals in water. In this study, natural aloe-emodin with π-conjugated structure was used as photosensitizer to react with macroporous resin polymethylmethacrylate (PMMA) under mild conditions to prepare composite photocatalysts AE/PMMAs. The photocatalyst underwent photogenerated electron migration under visible light to form ^•O₂^- and holes with high oxidation activity, which could realize efficient photocatalytic degradation of ofloxacin and diclofenac sodium and showed excellent stability, recyclability and industrial feasibility. This research has developed an efficient method of composite photocatalyst and realized the application of a natural photosensitizer in pharmaceutical degradations.

Stimulating fungal cell wall integrity by exogenous β-glucanase to improve the production of fungal natural products

The low production of natural products (NPs) is still the critical restrictive factor in exploiting their potential large-scale applications and a barrier to isolating and identifying other meaningful products. Given that the stimulation of cell wall integrity (CWI) has become a novel strategy to modulate the production of microbial natural products, herein, exogenous β-glucanase treatment was developed as an external cell wall β-glucan stress to stimulate the fungal CWI, and then to improve the production of fungal NPs. It was found that the production of fungal NPs cercosporin and sophorolipids, biosynthesized by Cercospora sp. and Starmerella bombicola, respectively, was significantly improved by the treatment of β-glucanase under a controllable dose. Moreover, it demonstrated that β-glucanase had an ability to stimulate fungal CWI through slight fungal superficial damage, thus facilitating the secretion of NPs. We expected that this easy-operating method to stimulate fungal CWI could be feasible to improve more fungal NPs production. KEY POINTS: • Exogenous β-glucanase stimulated the fungal cell wall integrity • Changing fungal cell walls modulated natural product production • β-glucanase with potential universal effects on more fungal natural products.