Biogenic Ag2O nanoparticles with "Hoja Santa" (Piper auritum) extract: characterization and biological capabilities.

The 'sacred leaf' or "Hoja Santa" (Piper auritum Kunth) has a great value for Mexican culture and has gained popularity worldwide for its excellent properties from culinary to remedies. To contribute to its heritage, in this project we proposed the green synthesis of silver oxide nanoparticles (Ag2O NPs) using an extract of "Hoja Santa" (Piper auritum) as a reducing and stabilizing agent. The synthesized Ag2O NPs were characterized by UV-Visible spectroscopy (plasmon located at 405 nm), X-ray diffraction (XRD) (particle size diameter of 10 nm), scanning electron microscopy (SEM) (particle size diameter of 13.62 ± 4.61 nm), and Fourier-transform infrared spectroscopy (FTIR) (functional groups from "Hoja Santa" attached to nanoparticles). Antioxidant capacity was evaluated using DPPH, ABTS and FRAP methods. Furthermore, the antimicrobial activity of NPs against a panel of clinically relevant bacterial strains, including both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Salmonella Enteritidis and Escherichia coli O157:H7), was over 90% at concentrations of 200 µg/mL. Additionally, we assessed the antibiofilm activity of the NPs against Pseudomonas aeruginosa (reaching 98% of biofilm destruction at 800 µg/mL), as biofilm formation plays a crucial role in bacterial resistance and chronic infections. Moreover, we investigated the impact of Ag2O NPs on immune cell viability, respiratory burst, and phagocytic activity to understand their effects on the immune system.

Generation of Photopolymerized Microparticles Based on PEGDA Hydrogel Using T-Junction Microfluidic Devices: Effect of the Flow Rates.

The formation of microparticles (MPs) of biocompatible and biodegradable hydrogels such as polyethylene glycol diacrylate (PEGDA) utilizing microfluidic devices is an attractive option for entrapment and encapsulation of active principles and microorganisms. Our research group has presented in previous studies a formulation to produce these hydrogels with adequate physical and mechanical characteristics for their use in the formation of MPs. In this work, hydrogel MPs are formed based on PEGDA using a microfluidic device with a T-junction design, and the MPs become hydrogel through a system of photopolymerization. The diameters of the MPs are evaluated as a function of the hydrodynamic condition flow rates of the continuous (Qc) and disperse (Qd) phases, measured by optical microscopy, and characterized through scanning electron microscopy. As a result, the following behavior is found: the diameter is inversely proportional to the increase in flow in the continuous phase (Qc), and it has a significant statistical effect that is greater than that in the flow of the disperse phase (Qd). While the diameter of the MPs is proportional to Qd, it does not have a significant statistical effect on the intervals of flow studied. Additionally, the MPs' polydispersity index (PDI) was measured for each experimental hydrodynamic condition, and all values were smaller than 0.05, indicating high homogeneity in the MPs. The microparticles have the potential to entrap pharmaceuticals and microorganisms, with possible pharmacological and bioremediation applications.

Jasmonic and Salicylic Acids Enhance Biomass, Total Phenolic Content, and Antioxidant Activity of Adventitious Roots of Acmella radicans (Jacq.) R.K. Jansen Cultured in Shake Flasks.

Acmella radicans (Asteraceae) is a plant native to America. Despite it having medicinal attributes, studies on its phytochemical properties are scarce, and biotechnological studies do not exist for this species. In this study, we established an adventitious root culture from A. radicans internodal segments in shake flasks with indole-3-butyric acid (IBA), and then elicited it with jasmonic acid (JA) and salicylic acid (SA). The total phenolic content and antioxidant activity were evaluated, and a comparison was made using in vitro plantlets and wild plants. Internodal segments with 0.1 mg/L IBA showed 100% root induction and exhibited better growth after transfer to shake flasks with MS liquid culture medium. JA had a significant effect on biomass increase compared to unelicited roots, mainly with 50 µM JA (28%), while SA did not show significant results. Root elicited with 100 µM (SA and JA) showed a 0.34- and 3.9-fold increase, respectively, in total phenolic content (TPC) compared to the control. The antioxidant activity was also significant, and a lower half-maximal inhibitory concentration (IC50) was observed as the AJ concentration increased. Roots elicited with AJ (100 µM) exhibited high antioxidant activity with DPPH (IC50 = 9.4 µg/mL) and ABTS (IC50 = 3.3 µg/mL) assays; these values were close to those for vitamin C (IC50 = 2.0 µg/mL). The TPC and antioxidant activity of in vitro plants and root cultured in shake flasks showed the lowest values in most cases; even the root cultures without elicitation were better than those of a wild plant. In this study, we demonstrated that A. radicans root culture is capable of producing secondary metabolites, while its production and antioxidant activity can be enhanced using jasmonic acid.