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Learning from biological systems such as Silicateins and their molecular mechanisms have paved the way for controlled synthesis of inorganic materials with advanced properties and high performances. In the case of zinc oxide (ZnO), conventional production methods are environmentally damaging and wasteful with the use of toxic and/or flammable solvents and precursors, extreme alkaline conditions requiring extra processing steps to neutralize, and lack satisfactory control of desired crystal habits for high value applications. Inspired by ZnO-binding peptides, we demonstrate a bioinspired synthesis and aspect ratio control of ZnO hexagonal prisms directly at 65°C using histidine in HMTA-zinc nitrate reaction system, with no seeding or substrate, yet well-defined morphology and conversion up to 40%. Histidine interferes with zinc ions, thereby stabilizing the system, affecting the conversion and particle morphology. We are now testing the performance of histidine in other ZnO synthesis systems to enable scalability of the bioinspired route.

Bioinspired synthesis of nanomaterials: Case study of zinc oxide

Individuals with medical implants are often at risk of developing life-threatening thrombi on the surface of these devices. Fibrinogen (Fgn) facilitates platelet recruitment by laterally aggregating at its αC domains into interconnected fibers that provide structure for thrombi. Thus, one method of preventing thrombogenesis is by inhibiting this process. The calculated optimal adsorption cites of the in silico human Fgn NJm on a hydrophobic thermoplastic surface model were congruent with existing literature, suggesting that on a polystyrene (PS) surface, Fgn is positioned with its αC domain exposed. Allowing a molecule to bind to the exposed αC domain will prevent the Fgn proteins from laterally aggregating. This study generated an in vitro bovine model of fiber formation on a hydrophobic PS surface to investigate the proficiency of a hydrophilic 14-peptide sequence derived from the Aα635-648 region of fibronectin, P-12 (PSHISKYILRWRPK), in achieving that end. Various amounts of bovine Fgn and P-12 were plated on PS and submerged in phosphate-buffered saline at various intervals. 100 μg/mL of Fgn acted as the monolayer that would initiate fibrin cluster formation, an additional 4 mg/mL of Fgn that, uninterrupted, would aggregate to form fibers, and 10μM of P-12 were added to investigate its impact on Fgn polymerization. Large fibers were observed in the absence of P-12, supporting the previous reports that the αC domains of the monolayer were opened by the hydrophobic interaction. Significantly smaller fibers were present when the P-12 was added alongside the surface monolayer, suggesting P-12 displaced certain sections, while minimal fiber formation occurred when P-12 was added afterward, which suggests that P-12 binds with Fgn to prevent the formation of fibrin clusters. This experiment confirms that P-12 blocks the ability of Fgn to execute fiber formation and that P-12 can displace Fgn from surfaces. If medical implants are manufactured with hydrophobic surfaces, this study suggests the introduction of P-12 can be used to mitigate thrombosis.

Development of a short peptide to prevent non-thrombogenic clot formation on hydrophobic surfaces

Electrocatalytic synthesis of H2O2 via two-electron oxygen reduction reaction (2e- ORR) has attracted tremendous interest in diversified fields, including wafer cleaning, paper manufacturing, and public sanitation. However, developing inexpensive, highly active, and selective catalysts is still a challenge for the large-scale electroproduction of H2O2. Here, we report a fluorine and sulfur dual-doping strategy for metal-free nanofibers to achieve comparable performances to metal-based catalysts. The optimized F/S dual-doping catalysts can afford an onset potential of 0.814 V versus reversible hydrogen electrode (RHE) and highly enhanced H2O2 selectivity of nearly 100%, superior to most of the recently reported carbon-based and metal-based counterparts. Experimental and theoretical computation results demonstrate that the manipulated free energy profiles and reduced energy barrier originate from the synergistic effect of intermolecular charge transfer coupled with electron spin redistribution in the adjacent carbon active sites, owing to the fluorine and sulfur heteroatom doping, respectively. This work can open the door to the design and implementation of inexpensive, large-scale, and highly efficient catalysts for the electroproduction of H2O2, and enjoys versatility to be extended to other catalytic fields, such as CO2 reduction, water splitting, and ammonia production.

Highly active and selective metal-free nanofibers for H2O2 electroproduction via F/S dual-doping

The COVID-19 pandemic has impacted the Green Chemistry Teaching and Learning Community. In 2020, universities and schools were forced to move towards online education. Digital technologies offer opportunities that facilitate some educational methods; however, they also can become barriers for an Inclusive Green Chemistry Education. Thousands of deaf students faced many difficulties with online teaching tools in Brazil. Unfortunately, this migration from face-to-face teaching to remote teaching increased the dropout rate among students in schools. Many reasons for this increase in dropouts were reported, for example non-attendance of a sign language interpreter and the absence of inclusive teaching methods. This urgent reality requires a pedagogical rethink. From this perspective, this work proposed and evaluated strategies to promote interactions between hearing teachers and deaf students during online classes of chemistry. Our method was applied to high school students in a public college in Brazil. Chemistry teachers and translator-interpreters of Brazilian Sign Language (Libras) planned the lessons. They worked together for more interactive and visual classes. Visualization tools are important to teach chemistry, according to Mahaffy's model. Our project was divided into five stages: survey questions (1), case study (2), visual-educational activity (3), interactions with social media (4) and (5) final test, which were approved by the Research Ethics Committee. Results showed that Libras is essential for communication. We confirmed a positive impact on the learning of students and an effective interest into sustainable development. Using social media ensured a constant communication with students. In conclusion, our inclusive methodology allowed introducing some principles of Green Chemistry in high school classes online. We helped deaf students to stay focused and develop metacognitive skills during the COVID-19 pandemic. An inclusion of participants was possible with a Systems Thinking perspective. We hope that new inclusive approaches should be a priority for Green Chemistry Teaching and Learning Community.

Promoting teacher-student interactions in green chemistry education: An inclusive approach for deaf students during the COVID-19 pandemic

Daily use of multiple medications is commonplace for many Americans. While pharmacists monitor prescriptions for drug interactions, consumers rarely check the possible side effects when using an over-the-counter product. In this fictional case study, Sam is prescribed clomipramine and ciprofloxacin, while also taking Tylenol PM.
All three medications are orally administered, and drug metabolism is catalyzed in the liver by cytochrome P450 enzymes (CYP450). CYP isoenzymes CYP1A2, CYP3A4 and CYP2C19 are responsible for clomipramine metabolism and formation of major bioactive metabolite desmethylclomipramine, while CYP2D6 hydroxylates clomipramine and metabolite into hydroxyclomipramine and hydroxydesmethylclomipramine, respectively. Multi-drug use can inhibit or induce metabolic activity.  The extent to which activity is affected is determined by dose and ligand-enzyme binding strength. Ciprofloxacin is a known CYP1A2 inhibitor, while diphenhydramine inhibits CYP2D6. Quantification and visualization of metabolites formed from clomipramine, ciprofloxacin, and diphenhydramine in rat liver microsomes was performed using compact mass spectrometry and high-performance liquid chromatography. Chromatograms were analyzed for molecular weights of parent clomipramine and metabolized products. Data indicated a reduction ranging from 21.1% to 30.1% inhibition of clomipramine metabolism into desmethylclomipramine. It was concluded that CYP isoenzymes CYP1A2, CYP3A4, and CYP2C19 played a role in diminishing clomipramine metabolite formation. These results illustrate the need for research and education when administering multiple drugs.

HPLC and CMS analysis of clomipramine metabolism: A multi-drug study

It has been reported that nearly 10 million deaths were caused by cancer in 2020. Focusing on early detection and treatment is highly recommended to reduce cancer mortality. Therefore, it is crucial to explore new technologies based on tumor markers that can be implemented in point-of-care tests for early diagnosis of the disease. One of these protein tumor biomarkers is a carcinoembryonic antigen (CEA), a glycoprotein whose concentration is a well-established sign of colorectal cancer, among others, and metastasis. This study was focused on developing a nanoaptasensor based on gold nanotriangles (AuNT) functionalized with CEA hairpin-aptamer to produce the complex CEA-aptamer. The chemical pretreatment of this aptamer with tris (2-carboxyethyl) phosphine hydrochloride (TCEP) was studied to break possible disulfide bridges present (R-S-S-R) and ensure the interaction between the gold nanotriangles and the aptamer sulfur (Au-S). Additionally, two types of molecules were added as blocking agents to promote the stabilization of the AuNT while maximizing the interaction of the CEA and the aptamer. By using thiolated polyethylene glycol with a terminal methoxy group (HS -PEG(8)-OMe) as a blocking agent, the stability of the gold nanotriangles is enhanced since the PEG prevents them from agglomerating. In contrast, small molecules provide less stability to the AuNT than the PEG, but their presence may reduce the steric hindrance for the formation of the complex CEA-aptamer. By taking advantage of gold nanotriangles’ optical properties, promising results were obtained for detecting CEA by monitoring the LSPR band. In addition, it is possible to implement a colorimetric qualitative detection with the nanoaptasensor by a lateral flow assay (LFA).

Design and optimization of an optical nanoaptasensor based on gold nanotriangles modified with two blocking agents for the detection of carcinoembryonic antigen

American Chemical Society

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