Control of planktonic bacterial cells and biofilms through magnetic hyperthermia

Disinfection of surfaces is a challenging task aggravated by bacteria's capacity to form biofilms, which enables them to survive and resist a wide variety of antimicrobial agents and hostile conditions. Potential application of magnetic hyperthermia (MH) as a new disinfection method against biofilms has been recently proposed however, studies comparing its performance and effectiveness on planktonic and biofilm cells from the same bacterial species remain unexplored. This work evaluated the effect of MH generated by iron oxide magnetic nanoparticles (MNP) against planktonic and biofilm cells Pseudomonas fluorescens, a major food spoilage microorganism. A P. fluorescens collection strain (ATCC 27663) was used and its biofilms allowed to form on silicone coupons during three days incubation in tryptic soy broth culture medium, at room temperature (20 ± 2ºC) and constant agitation of 120 rpm. Hyperthermia experiments were performed by applying an oscillating magnetic field of 873kHz and 100 Oe to several identical solutions of bacteria and MNP. To study cell viability as a function of temperature, magnetic heatings were performed at the same heating rate and up to different maximum temperatures. Bacterial survival was assessed through colony forming units count, while confocal laser scanning microscopy (CLS) was used to evaluate cellular membrane integrity of both bacterial life forms, as well as eventual effects of MH in biofilms' structure. Results showed a significant reduction (3 log) of viable planktonic cells when a maximum temperature of 40QC was reached, corresponding to only about 3 minutes of exposure to alternate magnetic field. A complete cellular eradication was achieved after only 8 minutes, when the maximum temperature was increased up to 55ºC. ln contrast, a significantly lower reduction of cellular viability was accomplished for biofilm s at the same temperatures, and no eradication was achieved even after 17 minutes of magnetic field exposure, reaching a maximum temperature of 60ºC. CLS images showed that MH inflicted cellular membrane damages both in planktonic and biofilm s cells, and also suggested that the outer cell layers of biofilms were more damaged than inner ones, as denoted by the higher amount of injured cells observed in the external layers. Summarizing, this work confirms the potential of MH as a disinfection method and shows for the first time its efficacy against a food spoilage microorganism. More importantly, it presents the first insights about how different bacterial life forms are affected by MH, showing a significantly different effectiveness against planktonic cells and biofilms

A carboxyl-functionalized covalent organic polymer for the efficient adsorption of saxitoxin

Saxitoxin (STX), the most widely distributed neurotoxin in marine waters and emerging cyanotoxin of concern in freshwaters, causes paralytic shellfish poisoning in humans upon consumption of contaminated shellfish. To allow for the efficient monitoring of this biotoxin, it is of high importance to find high-affinity materials for its adsorption. Herein, we report the design and synthesis of a covalent organic polymer for the efficient adsorption of STX. Two β-keto-enamine-based materials were prepared by self-assembly of 2,4,6-triformylphloroglucinol (Tp) with 2,5-diaminobenzoic acid (Pa-COOH) to give TpPa-COOH and with 2,5-diaminotoluene (Pa-CH3) to give TpPa-CH3. The carboxylic acid functionalized TpPa-COOH outperformed the methyl-bearing counterpart TpPa-CH3 by an order of magnitude despite the higher long-range order and surface area of the latter. The adsorption of STX by TpPa-COOH was fast with equilibrium reached within 1 h, and the Langmuir adsorption model gave a calculated maximum adsorption capacity, Qm, of 5.69 mg g-1, making this material the best reported adsorbent for this toxin. More importantly, the prepared TpPa-COOH also showed good reusability and high recovery rates for STX in natural freshwater, thereby highlighting the material as a good candidate for the extraction and pre-concentration of STX from aquatic environments.publishe

Biocompatibility and bioimaging potential of fruit-based carbon dots

Photo-luminescent carbon dots (CD) have become promising nanomaterials and their synthesis from natural products has attracted attention by the possibility of making the most of affordable, sustainable and, readily-available carbon sources. Here, we report on the synthesis, characterization and bioimaging potential of CDs produced from diverse extensively produced fruits: kiwi, avocado and pear. The in vitro cytotoxicity and anticancer potential of those CDs were assessed by comparing human epithelial cells from normal adult kidney and colorectal adenocarcinoma cells. In vivo toxicity was evaluated using zebrafish embryos given their peculiar embryogenesis, with transparent embryos developing ex-utero, allowing a real-time analysis. In vitro and in vivo experiments revealed that the synthesized CD presented toxicity only at concentrations of ≥1.5 mg mL−1. Kiwi CD exhibited the highest toxicity to both cells lines and zebrafish embryos, presenting lower LD50 values. Interestingly, despite inducing lower cytotoxicity in normal cells than the other CDs, black pepper CDs resulted in higher toxicity in vivo. The bio-distribution of CD in zebrafish embryos upon uptake was investigated using fluorescence microscopy. We observed a higher accumulation of CD in the eye and yolk sac, avocado CD being the ones more retained, indicating their potential usefulness in bio-imaging applications. This study shows the action of fruit-based CDs from kiwi, avocado and pear. However the compounds present in these fruit-based CDs and their mechanism of action as a bioimaging agent need to be further explored.N. Vasimalai and Marisa P Sárria acknowledge the financial support from the Marie Curie COFUND Programme (NanoTRAINforGrowth). I. Pinheiro acknowledges the financial support from NanoDesk project (SOE1/P1/E0215) co-financed by the Interreg SUDOE Programme through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Protection against paraquat-induced oxidative stress by Curcuma longa extract-loaded polymeric nanoparticles in zebrafish embryos

The link between oxidative stress and environmental factors plays an important role in chronic degenerative diseases; therefore, exogenous antioxidants could be an effective alternative to combat disease progression and/or most significant symptoms. Curcuma longa L. (CL), commonly known as turmeric, is mostly composed of curcumin, a multivalent molecule described as having antioxidant, anti-inflammatory and neuroprotective properties. Poor chemical stability and low oral bioavailability and, consequently, poor absorption, rapid metabolism, and limited tissue distribution are major restrictions to its applicability. The advent of nanotechnology, by combining nanosacale with multi-functionality and bioavailability improvement, offers an opportunity to overcome these limitations. Therefore, in this work, poly-Ɛ-caprolactone (PCL) nanoparticles were developed to incorporate the methanolic extract of CL, and their bioactivity was assessed in comparison to free or encapsulated curcumin. Their toxicity was evaluated using zebrafish embryos by applying the Fish Embryo Acute Toxicity test, following recommended OECD guidelines. The protective effect against paraquat-induced oxidative damage of CL extract, free or encapsulated in PCL nanoparticles, was evaluated. This herbicide is known to cause oxidative damage and greatly affect neuromotor functions. The overall results indicate that CL-loaded PCL nanoparticles have an interesting protective capacity against paraquat-induced damage, particularly in neuromuscular development that goes well beyond that of CL extract itself and other known antioxidants.Marisa P. Sarria was supported by Marie Skłodowska—Curie Actions from European Union’s 7th Framework Programme for Research, Technological Development and Demonstration under Grant Agreement 600375. This work was supported by the strategic programme UID/BIA/04050/ 2019 funded by national funds through the Fundação para a Ciência e a Tecnologia I.P. Marisa P. Sárria was supported by Marie Curie COFUND funding from the European Union’s 7th Framework Programme for research, technological development, and demonstration under grant agreement 600375. Begoña Espiña is supported by the co-funding from Northern Regional Operational Program through the Project NORTE-45-2015-02 Nanotechnology based functional solutions. B.E. acknowledges the financial support of the project SbDtoolBox—Nanotechnology-based tools and tests for Safer-by-Design nanomaterials, with the reference nº NORTE-01-0145-FEDER-000047, funded by Norte2020—North-Regional Operational Programme under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)

Fruit-based carbon dots as fluorescent probes: in vitro and in vivo toxicity evaluation

MNE2017 - 43rd International Conference on Micro and Nanoengineering (Conference Booklet)New solutions for biomedical purposes are a major focus of interest for the development of new nanomaterials. In comparison to traditional metal-based quantum dots, photoluminescent carbon-dots are greater in terms of aqueous solubility, chemical inertness, simple modification and fluorescent proprieties. In this work C-dots derived from kiwi and avocado and synthesized using a green method were evaluated for their toxicity and bioimaging in vitro and in vivo. Normal and cancer cells lines, and zebrafish embryos were used as in vitro an in vivo models, respectively, either for toxicological profile and confocal imaging. Both C-dots showed toxicity profiles in the range of mg/mL concentrations inducing delays in zebrafish embryos development. Concentrations of kiwi and avocado C-dots used for confocal bioimaging were adjusted below the NOAEL accordingly.info:eu-repo/semantics/publishedVersio

Correlative Light, Electron Microscopy and Raman Spectroscopy Workflow To Detect and Observe Microplastic Interactions with Whole Jellyfish.

Many researchers have turned their attention to understanding microplastic interaction with marine fauna. Efforts are being made to monitor exposure pathways and concentrations and to assess the impact such interactions may have. To answer these questions, it is important to select appropriate experimental parameters and analytical protocols. This study focuses on medusae of Cassiopea andromeda jellyfish: a unique benthic jellyfish known to favor (sub-)tropical coastal regions which are potentially exposed to plastic waste from land-based sources. Juvenile medusae were exposed to fluorescent poly(ethylene terephthalate) and polypropylene microplastics (<300 μm), resin embedded, and sectioned before analysis with confocal laser scanning microscopy as well as transmission electron microscopy and Raman spectroscopy. Results show that the fluorescent microplastics were stable enough to be detected with the optimized analytical protocol presented and that their observed interaction with medusae occurs in a manner which is likely driven by the microplastic properties (e.g., density and hydrophobicity)

BSA/ASN/Pol407 nanoparticles for acute lymphoblastic leukemia treatment

During the treatment of acute lymphoblastic leukemia (ALL) with asparaginase (ASN) there is an accumulation of ammonia in the body as result of asparagine hydrolysis. This accumulation known as hyperammonemia is one of the main side-effects of this therapy. To avoid hyperammonemia is urgent to develop new strategies for ammonia retention. Herein is presented the immobilization of ASN into bovine serum albumin/poloxamer 407 (BSA/Pol407) nanoparticles. The ability of the developed nanoparticles to hydrolyze asparagine while retaining the forming ammonia is also explored. Different percentages of ASN were entrapped into BSA nanoparticles coated with Poloxamer 407 and were prepared by high-pressure homogenization. The nanoparticles were characterized regarding their physico-chemical properties, stability, capacity to retain ammonia and safety using zebrafish embryos as an in vivo model of toxicity. The BSA/ASN25%/Pol407 nanoparticles were selected as the best formulation to hydrolyze asparagine using the lowest nanoparticle concentration. These nanoparticles presented physical characteristics suitable for an intravenous application and were capable to retain the forming ammonia decreasing the negative effect of free ASN on zebrafish survival. These nanoparticles could potentially be used to prevent hyperammonemia during ALL treatment with ASN.This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01- 0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145- FEDER-000004) and Nanotechnology Based Functional Solutions (NORTE-01-0145-FEDER-000019) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. We also acknowledge the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through Fundação para a Ciência e a Tecnologia (FCT) and by the ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI). Marisa P. Sárria was supported by Marie Curie COFUND funding from the European Union’s 7th Framework Programme for research, technological development and demonstration under grant agreement 600,375. Artur Ribeiro and Ana Tinoco thanks FCT for funding the scholarships with the references SFRH/BPD/98388/2013, SFRH/BD/ 114035/2015, respectively.info:eu-repo/semantics/publishedVersio

Adsorption of marine phycotoxin okadaic acid on a covalent organic framework

Phycotoxins, compounds produced by some marine microalgal species, can reach high concentrations in the sea when a massive proliferation occurs, the so-called harmful algal bloom. These compounds are especially dangerous to human health when concentrated in the digestive glands of seafood. In order to generate an early warning system to alert for approaching toxic outbreaks, it is very important to improve monitoring methods of phycotoxins in aquatic ecosystems. Solid-phase adsorption toxin tracking devices reported thus far based on polymeric resins have not been able to provide an efficient harmful algal bloom prediction system due to their low adsorption capabilities. In this work, a water-stable covalent organic framework (COF) was evaluated as adsorbent for the hydrophobic toxin okadaic acid, one of the most relevant marine toxins and the parental compound of the most common group of toxins responsible for the diarrhetic shellfish poisoning. Adsorption kinetics of okadaic acid onto the COF in seawater showed that equilibrium concentration was reached in only 60 min, with a maximum experimental adsorption of 61 mg g1. Desorption of okadaic acid from the COF was successful with both 70% ethanol and acetonitrile as solvent, and the COF material could be reused with minor losses in adsorption capacity for three cycles. The results demonstrate that COF materials are promising candidates for solid-phase adsorption in water monitoring devices.This article is a result of the project Nanotechnology Based Functional Solutions (NORTE-01-0145-FEDER-000019), supported by Norte Portugal Regional Operational Programme (NORTE2020) under the PORTUGAL 2020 Partnership Agreement through the European Regional Development Fund (ERDF). This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 600375.info:eu-repo/semantics/publishedVersio

Bioaccumulation of titanium dioxide nanoparticles in green (Ulva sp.) and red (Palmaria palmata) seaweed

A bioaccumulation study in red (Palmaria palmata) and green (Ulva sp.) seaweed has been carried out after exposure to different concentrations of citrate-coated titanium dioxide nanoparticles (5 and 25 nm) for 28 days. The concentration of total titanium and the number and size of accumulated nanoparticles in the seaweeds has been determined throughout the study by inductively coupled plasma mass spectrometry (ICP-MS) and single particle-ICP-MS (SP-ICP-MS), respectively. Ammonia was used as a reaction gas to minimize the effect of the interferences in the 48Ti determination by ICP-MS. Titanium concentrations measured in Ulva sp. were higher than those found in Palmaria palmata for the same exposure conditions. The maximum concentration of titanium (61.96 ± 15.49 μg g−1) was found in Ulva sp. after 28 days of exposure to 1.0 mg L−1 of 5 nm TiO2NPs. The concentration and sizes of TiO2NPs determined by SP-ICP-MS in alkaline seaweed extracts were similar for both seaweeds exposed to 5 and 25 nm TiO2NPs, which indicates that probably the element is accumulated in Ulva sp. mainly as ionic titanium or nanoparticles smaller than the limit of detection in size (27 nm). The implementation of TiO2NPs in Ulva sp. was confirmed by electron microscopy (TEM/STEM) in combination with energy dispersive X-Ray analysis (EDX)The authors wish to thank the fnancial support of Ministerio de Economía y Competitividad (project INNOVANANO, reference RT2018-099222-B-100), European Union (INTERREG Atlantic Area, project NANOCULTURE, reference EAPA590/2018), and Xunta de Galicia (Grupo de Referencia Competitiva, grant number ED431C 2022/29)S