Marisa M. Beppu

Removal of glyphosate herbicide from water using biopolymer membranes

Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. The adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. The membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. The results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). The AG membrane did not show any adsorption capacity for this herbicide. The pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. The SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. The results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to treat a water sample contaminated with glyphosate. Biopolymer membranes therefore potentially offer a versatile method to eliminate agricultural chemicals from water supplies.

Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa

In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum.

Hyaluronan/chitosan nanofilms assembled layer-by-layer and their antibacterial effect: A study using Staphylococcus aureus and Pseudomonas aeruginosa

In the last few years, chitosan-based coatings have been proposed as antibacterial surfaces for biomedical devices in order to prevent nosocomial infections. In that sense, this work reports the optimized synthesis of hyaluronan/chitosan (HA/CHI) nanofilms assembled layer-by-layer in order to maximize the antibacterial effect for two important human pathogenic bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. In this assembly, HA forms a soft, highly hydrated, and nontoxic film, whereas CHI shows the antimicrobial characteristics. Our HA/CHI nanofilm synthesis optimization was based on changing pH values of the biopolymer stem-solutions and the consequent variation of their ionization degree. Furthermore, the surface density of primary amino groups, which are related to the antibacterial effect, was also enhanced by increasing the number of HA/CHI bilayers. The antibacterial effect of HA/CHI nanofilms was evaluated by the spread plate counting method for both bacteria. These results were correlated with the morphology of nanofilms (characterized using SEM and AFM), as well as with their chemical properties studied by UV-vis, Kelvin Probe Force microscopy and XPS spectroscopy.

Liposome-Loaded Cell Backpacks.

Cell backpacks, or micron-scale patches of a few hundred nanometers in thickness fabricated by layer-by-layer (LbL) assembly, are potentially useful vehicles for targeted drug delivery on the cellular level. In this work, echogenic liposomes (ELIPs) containing the anticancer drug doxorubicin (DOX) are embedded into backpacks through electrostatic interactions and LbL assembly. Poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA)n , and poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/SPS)n film systems show the greatest ELIP incorporation of the films studied while maintaining the structural integrity of the vesicles. The use of ELIPs for drug encapsulation into backpacks facilitates up to three times greater DOX loading compared to backpacks without ELIPs. Cytotoxicity studies reveal that monocyte backpack conjugates remain viable even after 72 h, demonstrating promise as drug delivery vehicles. Because artificial vesicles can load many different types of drugs, ELIP containing backpacks offer a unique versatility for broadening the range of possible applications for cell backpacks.

Antibacterial silk fibroin/nanohydroxyapatite hydrogels with silver and gold nanoparticles for bone regeneration

The rapid emergence of antibiotic resistance is becoming an imminent problem in bone tissue engineering, and therefore biomaterials must be modified to promote the tissue integration before bacterial adhesion. In this work, silk fibroin/nanohydroxyapatite hydrogel was modified with in situ synthesized silver and gold nanoparticles (AgNPs and AuNPs), taking advantage of the tyrosine amino acid. The presence of AgNPs and AuNPs in the hydrogels was characterized by UV spectrophotometer, transmission electron microscopy and thermogravimetric analysis. In vitro antimicrobial studies revealed that hydrogels with AgNPs and AuNPs exhibited significant inhibition ability against both gram-positive and gram-negative bacteria. Cytocompatibility studies carried out using osteoblastic cells revealed that up to 0.5 wt% of AgNPs, and for all concentrations of AuNPs, the hydrogels can be effectively used as antimicrobial materials, without compromising cell behavior. On the basis of the aforementioned observations, these hydrogels are very attractive for bone tissue engineering.

Optimization of Amine-Rich Multilayer Thin Films for the Capture and Quantification of Prostate-Specific Antigen

It is demonstrated that poly(allylamine hydrochloride)/poly(styrenesulfonate) (PAH/SPS) multilayer films can be successfully tailored for the capture and detection of small biomolecules in dilute concentrations. Based on in vitro results, these films could be potentially applied for rapid and high-throughput diagnosis of dilute biomarkers in serum or tissue. PAH presents functional amino groups that can be further reacted with desired chemistries in order to create customizable and specific surfaces for biomolecule capture. A variety of film assembly characteristics were tested (pH, molecular weight of PAH, and ionic strength) to tune the biotinylation and swelling behavior of these films to maximize detection capabilities. The resultant optimized biotinylated PAH/SPS 9.3/9.3 system was utilized in conjunction with quantum dots (Qdots) to capture and detect a dilute biomarker for prostate cancer, prostate-specific antigen (PSA). Compared to previous work, our system presents a good sensitivity for PSA detection within the clinically relevant range of 0.4-100 ng/mL.

Antibacterial and non-cytotoxic ultra-thin polyethylenimine film

In recent years, a common strategy, to obtain more uniform and controlled synthesis of polyelectrolytes multilayers (PEMs), relies on a previous polyethylenimine (PEI) coating of the substrate surface. PEI is a synthetic cationic polymer which provides a positive charge distribution on the materials to be covered with PEMs. Despite being an important step, this pre-layer deposition is frequently overlooked and no comprehensive characterizations or deep discussions are reported in literature. In that sense, this work reports on the synthesis of a typical PEI film that works as a precursor for PEMs, and its detailed physicochemical characterization. As many PEMs are produced for antibacterial and biomedical applications, the cytotoxicity of the film was also tested using fibroblasts, and its antibacterial activity was studied using Staphylococcus aureus and Pseudomonas aeruginosa. Our results present the formation of an ultra-thin film of PEI with a thickness around 3.5nm, and with a significant percent of NH3+ (35% of the total amount of N) in its chemical structure; NH3+ is a key chemical group because it is considered an important bacterial killer agent. The film was stable and did not present important cytotoxic effect for fibroblasts up to 7days, contrary to other reports. Finally, the PEI film showed high antibacterial activity against the S. aureus strain: reductions in cell density were higher than 95% up to 24h.

Preface: 10th Brazilian meeting on adsorption

In 2014, Brazil held the FIFA World Cup, which was the most evidenced event in the worldwide community. However, we were also proud to host some other meetings that is boosting Brazil into a world class scientific production. Two months earlier, the Brazilian adsorption community promoted the 10th Brazilian Meeting on Adsorption (EBA10), the most expressive national conference in the field. This edition was chaired by Federal University of Sao Paulo (UNIFESP) Diadema, held from April 27th to 30th, in Guaruja, Sao Paulo. Reaching its tenth edition, EBA has experienced a growing interest by Brazilian and international scientific and business community. To understand this growing, we need to know a little bit of history: the first EBA happened in Fortaleza, Ceara on June 1996, organized by an initiative of a group of professors at the Federal University of Ceara, led by Celio Loureiro Cavalcante Jr, PhD. This first meeting showed that the initiative was timely, not only because it relied on the presence of Prof. Douglas Morris Ruthven, PhD, but also by the number of participants (about 100) and quality of the 65 papers presented. After six editions more (Table 1), EBA’s growth came along breaking the country’s frontiers. For this reason, the city of Campina Grande/PB received the EBA7 on June 2008, in which the 1st South American Symposium on Adsorption, Science and Technology and the 1st South American School on Adsorption were held in parallel. The 9th edition, in Recife/PE, held the 1st Ibero-American Symposium on Adsorption (IBA1), which was a longstanding demand of many researchers on Adsorption area who met sporadically at conferences like the Fundamentals of Adsorption (FOA). The simultaneous occurrence of events led to a massive participation of researchers from the Ibero-Latin American region. In this meeting, it was decided that the IBAs will be held every three years. Prof. Juan Carlos Moreno-Pirajan, PhD, from Universidad de los Andes (Colombia) is the chairman of IBA2, which will be held from 26th to 30th April, 2015, in Cartagena de Indias—a World Cultural Heritage by UNESCO. This growth trend that EBA experienced was the driving force that motivated a group of young professors from the Chemical Engineering undergraduate program at UNIFESP to accept the invitation to organize the EBA10. The Enseada Beach in Guaruja, a beautiful coastal city 90 km far from Sao Paulo was chosen as the place to host this milestone tenth edition. The development of human resources and the interest of undergraduate and graduate students were highlighted by carrying out the School of Adsorption during EBA10. As its name implies, in the school lessons on various areas of adsorption are taught by professors from educational and research institutions and companies. International invited speakers were responsible for five plenary lectures. Nine keynotes also took place held by international and Brazilian researchers, from academia and business community in order to foster research partnerships. Distributed in eight oral sessions and two poster sessions, 228 papers were presented. The conference was attended by 334 participants from Brazil, South America and Europe. We thank our invited speakers (Gino Baron, Alois Jungbauer, Alirio Rodrigues, Abdelhamid Sayari, Juan Carlos I. T. L. Bresolin (&) Department of Exact and Earth Sciences, Federal University of Sao Paulo (UNIFESP), Diadema, SP 09972-270, Brazil e-mail: igor.bresolin@gmail.com