Quaternization of cassava starch and determination of antimicrobial activity against bacteria and coronavirus.

This study describes the novel development of quaternized cassava starch (Q-CS) with antimicrobial and antiviral properties, particularly effective against the MHV-3 coronavirus. The preparation of Q-CS involved the reaction of cassava starch (CS) with glycidyltrimethylammonium chloride (GTMAC) in an alkaline solution. Q-CS physicochemical properties were determined by FTIR, NMR, elemental analysis, zeta potential, TGA, and moisture sorption. FTIR and NMR spectra confirmed the introduction of cationic groups in the CS structure. The elemental analysis revealed a degree of substitution (DS) of 0.552 of the cationic reagent on the hydroxyl groups of CS. Furthermore, Q-CS exhibited a positive zeta potential value (+28.6 ± 0.60 mV) attributed to the high positive charge density shown by the quaternary ammonium groups. Q-CS demonstrated lower thermal stability and higher moisture sorption compared to CS. The antimicrobial activity of Q-CS was confirmed against Escherichia coli (MIC = 0.156 mg mL-1) and Staphylococcus aureus (MIC = 0.312 mg mL-1), along with a remarkable ability to inactivate 99% of MHV-3 coronavirus after only 1 min of direct contact. Additionally, Q-CS showed high cell viability (close to 100%) and minimal cytotoxicity effects, guaranteeing its safe use. Therefore, these findings indicate the potential use of Q-CS as a raw material for antiseptic biomaterials.

Antiviral and antibacterial activity of sodium alginate/poly(diallyldimethylammonium chloride) polyelectrolyte film for packaging applications.

Pathogen agents, such as bacteria and virus, can contaminate plastic surfaces, particularly those used in food packaging. This study proposed to prepare a polyelectrolyte film with antiviral and antibacterial activity based on sodium alginate (SA) and poly(diallyldimethylammonium chloride) (PDADMAC), a cationic polymer with sanitizing properties. In addition, the physicochemical properties of the polyelectrolyte films were also evaluated. The polyelectrolyte films showed continuous, compact, and crack-free structures. The FTIR analysis confirmed the ionic interaction between SA and PDADMAC. Adding PDADMAC significantly affected the mechanical properties of the films (p < 0.05), increasing the maximum tensile strength (from 8.66 ± 1.55 MPa to 18.1 ± 1.77 MPa). However, polyelectrolyte films showed higher water vapor permeability values due to the strong hydrophilicity of PDADMAC, representing a 43 % average increase compared with the control film. Also, thermal stability improved with the incorporation of PDADMAC. The selected polyelectrolyte film inactivated 99.8 % of SARS-CoV-2 after 1 min in direct contact with the virus, in addition to having an inhibitory effect against Staphylococcus aureus and Escherichia coli bacteria. Therefore, this study demonstrated the efficacy of using PDADMAC in the preparation of polyelectrolyte sodium alginate-based films with improvements in physicochemical properties and especially with antiviral activity against SARS-CoV-2.

Selection and Control of Process Conditions Enable the Preparation of Curcumin-Loaded Poly(lactic-co-glycolic acid) Nanoparticles of Superior Performance.

Curcumin (CUR) is one natural bioactive compound acknowledged for diverse therapeutic activities, but its use is hindered by its poor bioavailability, fast metabolism, and susceptibility to pH variations and light exposure. Thus, the encapsulation in poly(lactic-co-glycolic acid), or PLGA, has been successfully used to protect and enhance CUR absorption in the organism, making CUR-loaded PLGA nanoparticles (NPs) promising drug delivery systems. However, few studies have focused beyond CUR bioavailability, on the environmental variables involved in the encapsulation process, and whether they could help obtain NPs of superior performance. Our study evaluated pH (3.0 or 7.0), temperature (15 or 35 °C), light exposure, and inert atmosphere (N2) incidence in the encapsulation of CUR. The best outcome was at pH 3.0, 15 °C, without light incidence, and without N2 usage. This best nanoformulation showed NP size, zeta potential, and encapsulation efficiency (EE) of 297 nm, -21 mV, and 72%, respectively. Moreover, the CUR in vitro release at pH values 5.5 and 7.4 suggested different potential applications for these NPs, one of which was demonstrated by the effective inhibition of multiple bacteria (i.e., Gram-negative, Gram-positive, and multi-resistant) in the minimal inhibition concentration assay. Besides, statistical analyses confirmed a significant impact of temperature on the NP size; in addition, temperature, light, and N2 affected the EE of CUR. Thus, the selection and control of process variables resulted in higher CUR encapsulation and customizable outcomes, ultimately enabling more economical processes and providing future scale-up guidelines.

Curcumin encapsulation in functional PLGA nanoparticles: A promising strategy for cancer therapies.

Nanoparticles have emerged as promising drug delivery systems for the treatment of several diseases. Novel cancer therapies have exploited these particles as alternative adjuvant therapies to overcome the traditional limitations of radio and chemotherapy. Curcumin is a natural bioactive compound found in turmeric, that has been reported to show anticancer activity against several types of tumors. Despite some biological limitations regarding its absorption in the human body, curcumin encapsulation in poly(lactic-co-glycolic acid) (PLGA), a non-toxic, biodegradable and biocompatible polymer, represents an effective strategy to deliver a drug to a tumor site. Furthermore, PLGA nanoparticles can be engineered with targeting moieties to reach specific cancer cells, thus enhancing the antitumor effects of curcumin. We herein aim to bring an up-to-date summary of the recently developed strategies for curcumin delivery to different types of cancer cells through encapsulation in PLGA nanoparticles, correlating their effects with those of curcumin on the biological capabilities acquired by cancer cells (cancer hallmarks). We discuss the targeting strategies proposed for advanced curcumin delivery and the respective improvements achieved for each cancer cell analyzed, in addition to exploring the encapsulation techniques employed. The conjugation of correct encapsulation techniques with tumor-oriented targeting design can result in curcumin-loaded PLGA nanoparticles that can successfully integrate the elaborate network of development of alternative cancer treatments along with traditional ones. Finally, the current challenges and future demands to launch these nanoparticles in oncology are comprehensively examined.

Silver nanoparticles incorporated into nanostructured biopolymer membranes produced by electrospinning: a study of antimicrobial activity

abstract This study examines the antimicrobial activity of silver nanoparticles incorporated into nanostructured membranes made of cellulose acetate (CA) and blends of chitosan/poly-(ethylene oxide, CTS/PEO) and prepared by electrospinning. The formation of chemically synthesized Ag nanoparticles (AgNPs) was monitored by UV-visible spectroscopy (UV-Vis) and characterized by transmission electron microscopy (TEM). The size distribution of the AgNPs was measured by dynamic light scattering (DLS), with an average size of approximately 20 nm. The presence of AgNPs on the surface of electrospun nanofibers was observed by field emission electron microscopy (FEG) and confirmed by TEM. The antimicrobial activity of AgNPs incorporated into nanostructured membranes made of CA and CTS/PEO electrospun nanofibers was evaluated in the presence of both Gram-positive bacteria, such as Staphylococcus aureus ATCC 29213 and Propionibacterium acnes ATCC 6919, and Gram-negative bacteria, such as Escherichia coli ATCC 25992 and Pseudomonas aeruginosa ATCC 17933. Microbiological results showed that the presence of AgNPs in CA and CTS/PEO nanostructured membranes has significant antimicrobial activity for the Gram-positive bacteria Escherichia coli and Propionibacterium acnes.

resumo Neste trabalho avaliou-se a atividade antimicrobiana das nanopartículas de prata (AgNPs) incorporadas em membranas de acetato celulose (AC) e blendas de quitosana/poli-óxido de etileno (CTS/PEO) preparadas pelo método de eletrofiação. A formação das AgNPs previamente sintetizadas foi monitorada por UV-Vis e caracterizada por microscopia eletrônica de transmissão (MET). A distribuição de tamanho das AgNPs foi mensurada por espalhamento de luz dinâmico, com tamanho médio em torno de 20 nm. A presença das NPs na superfície das nanofibras eletrofiadas foi observada por microscopia eletrônica com emissão de campo (FEG) e confirmada por MET. A atividade antimicrobiana das membranas nanoestruturadas de AC e CTS/PEO foi avaliada pelo uso de bactérias Gram-positivas, tais como Staphylococcus aureus ATCC 29213 e Propionibacterium acnes ATCC 6919, e Gram-negativas, como Escherichia coli ATCC 25992 e Pseudomonas aeruginosa ATCC 17933. Os resultados microbiológicos mostraram a presença das AgNPs nas membranas de AC e CTS/PEO com significativa atividade antimicrobiana para Escherichia coli e Propionibacterium acnes, respectivamente.