Search

Evaluating compostability is increasingly essential for proving commercial bio-based cutlery or packaging since these materials must biodegrade under controlled conditions quickly. Utensils for eating represent Mexico's most popular consumer single-use materials, and Mexican regulations based on biodegradation or compostability are still vague and lack scientific evaluations. This study analyzed three bio-based polymeric materials (bags, dishes, and forks) from commercial brands following Mexican regulations and using various analytical techniques to verify their biodegradability and compostability. First, weight loss measurements, stress-strain tests, and topographic imaging were applied for preliminary observations at the macro scale up to 90 days of compostability. Besides, spectroscopy, microscopy, and thermal techniques indicate changes and behavior of the bio-based materials depending on the composition. The results suggest that bags exhibited the highest decomposition rate (80 %) compared to dishes and forks. Similarly, mechanical resistance indicates a reduction of 62 % for bags, 30 % for dishes, and almost none for forks. Texture image analysis revealed that the complexity and roughness of the materials increased over time, correlating with the physical changes observed. These results indicate minimal surface topography changes and higher stiffness for dishes and forks, indicating low biodegradability. SEM images supported these findings, showing surface degradation in bags and dishes but not in forks. FTIR and XRD analyses confirmed the presence of polyamide (bags) and polypropylene (dishes and forks). These results reduce biodegradation and differ from the claims made by manufacturers. The thermal analysis found similar results, indicating that the materials' thermal stability decreased after degradation, which is related to lower biodegradability and compostability. Overall, the study concluded only bags meet the criteria for compostability in national regulations. However, dishes and forks made of petroleum-derived polymers have higher resistance to natural and microbial degradation., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nowadays, the use of super-resolution microscopy (SRM) is increasing globally due to its potential application in several fields of life sciences. However, a detailed and comprehensive guide is necessary for understanding a single-frame image's resolution limit. This study was performed to provide information about the structural organisation of isolated cellulose fibres from garlic and agave wastes through fluorophore-based techniques and image analysis algorithms. Confocal microscopy provided overall information on the cellulose fibres' microstructure, while techniques such as total internal reflection fluorescence microscopy facilitated the study of the plant fibres' surface structures at a sub-micrometric scale. Furthermore, SIM and single-molecule localisation microscopy (SMLM) using the PALM reconstruction wizard can resolve the network of cellulose fibres at the nanometric level. In contrast, the mean shift super-resolution (MSSR) algorithm successfully determined nanometric structures from confocal microscopy images. Atomic force microscopy was used as a microscopy technique for measuring the size of the fibres. Similar fibre sizes to those evaluated with SIM and SMLM were found using the MSSR algorithm and AFM. However, the MSSR algorithm must be cautiously applied because the selection of thresholding parameters still depends on human visual perception. Therefore, this contribution provides a comparative study of SRM techniques and MSSR algorithm using cellulose fibres as reference material to evaluate the performance of a mathematical algorithm for image processing of bioimages at a nanometric scale. In addition, this work could act as a simple guide for improving the lateral resolution of single-frame fluorescence bioimages when SRM facilities are unavailable., (© 2024 Royal Microscopical Society.)

The pollution caused by petroleum-derived plastic materials has become a major environmental problem that has encouraged the development of new compostable and environmentally friendly materials for food packaging based on biomodified polymers with household residues. This study aims to design, synthesize, and characterize a biobased polymeric microstructure film from polyvinyl alcohol and chitosan reinforced with holocellulose from spent coffee grounds for food-sustainable packaging. Chemical isolation with a chlorite-based solution was performed to obtain the reinforced holocellulose from the spent coffee ground, and the solvent casting method was used to obtain the films to study. Physicochemical and microscopic characterizations were conducted to identify and select the best formulations using a simplex-centroid design analysis. The response surface methodology results indicate that the new packaging material obtained with equal amounts of polymers and reinforced material (1:1:1) possesses the appropriate barrier properties and microstructural character to prevent water attack and hydrophobic behavior and thus could be used as an alternative for food packaging materials., (© 2024 Wiley Periodicals LLC.)

Arthrospira maxima is a source of phycobiliproteins with different nutraceutical properties, e.g. antioxidant and anti-inflammatory activities. The current study was aimed at the elaboration, characterization, and evaluation of the anti-inflammatory effect of the phycobiliprotein nanoparticles extracted from Arthrospira maxima. Previously freeze-dried phycobiliproteins were milled by high-energy ball milling until reaching a nanometric size (optimal time: 4 h). Microscopy techniques were used for the characterization of the size and morphology of phycobiliproteins nanoparticles. Additionally, a spectroscopic study evidenced that nanosized reduction induced an increase in the chemical functional groups associated with its anti-inflammatory activity that was tested in a murine model, showing an immediate inflammatory effect. The novelty and importance of this contribution was to demonstrate that high energy ball milling is an emerging and green technology that can produce phycobiliprotein nanoparticles on a large-scale, without the use of organic solvents, to test their nutraceutical properties in a biological model by intragastric administration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This work analyzes the role of the tight junction (TJ) protein ZO-2 on mechanosensation. We found that the lack of ZO-2 reduced apical membrane rigidity measured with atomic force microscopy, inhibited the association of γ-actin and JAM-A to the cell border, and instead facilitated p114RhoGEF and afadin accumulation at the junction, leading to an enhanced mechanical tension at the TJ measured by FRET, with a ZO-1 tension probe, and increased tricellular TJ tension. Simultaneously, adherens junction tension measured with an E-cadherin probe was unaltered. The stability of JAM-A and ZO-2 binding was assessed by a collaborative in silico study. The absence of ZO-2 also impacted the cell response to the substrate, as monolayers plated in 20 kPa hydrogels developed holes not seen in parental cultures and displayed a retarded elongation and formation of cell aggregates. The absence of ZO-2 was sufficient to induce YAP and Snail nuclear accumulation in cells cultured over glass, but when ZO-2 KD cells were plated in nanostructured ridge arrays, they displayed an increased abundance of nuclear Snail and conspicuous internalization of claudin-4. These results indicate that the absence of ZO-2 also impairs the response of cells to substrate stiffness and exacerbates transformation triggered by substrate topography.

A hybrid ultra-light and porous cellulose aerogel was prepared by extracting cellulose fibers from white paper, alkali/urea as a crosslinker agent, and functionalized with CNTs and pure anatase TiO 2 nanoparticles. Since CNTs work as mechanical reinforcement for aerogels, physical and mechanical properties were measured. Besides, since TiO 2 acts as a photocatalyst for degrading dyes (rhodamine B and methylene blue), UV-Vis spectroscopy under UV light, visible light, and darkroom was used to evaluate the degradation process. XRD, FTIR, and TGA were employed to characterize the structural and thermal properties of the composite. The nanostructured solid network of aerogels was visualized in SEM microscopy confirming the structural uniformity of cellulose and TiO 2 -CNTs onto fibers. Moreover, CLSM was used to study the nano-porous network distribution of cellulose fibers and porosity, and the functionalization process in a detailed way. Finally, the photocatalytic activity of aerogels was evaluated by degradation of dye aqueous solutions, with the best photocatalytic removal (>97 %) occurring after 110 min of UV irradiation. In addition, HPLC-MS facilitated the proposed mechanism for the degradation of dyes. These results confirm that cellulose aerogels coupled with nanomaterials enable the creation of economic support to reduce water pollution with higher decontamination rates., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Microplastics (MPs) alone may endanger the health and fitness of aquatic species through different mechanisms. However, the harmful effects of these when mixed with other emerging contaminants require additional research. Herein, we aimed to determine whether a mixture of MPs with metformin (MET) or guanylurea (GUA) might induce embryotoxicity and oxidative stress in Danio rerio. Upon exposure to mixtures, our results showed MPs reduced the mortality rate of MET and GUA in embryos. Moreover, the severity and the rate of malformations were also decreased in all mixtures with MPs. Concerning oxidative stress, our findings indicated MET, GUA, MPs, and the mixtures increased the levels of lipoperoxidation, hydroperoxide content, and protein carbonyl content in D. rerio larvae. However, the oxidative damage induced in all mixtures was lower than that produced by both drugs alone. Thus, it is likely that the accumulation of MPs avoided the entrance of MET and GUA into the embryos. Once the embryo hatched, MPs did only remain accumulated in the yolk sac of larvae and did not translocate to other organs. Our risk assessment analysis confirmed that MPs shrunk the damage produced by MET and GUA. In a nutshell, MPs mitigate the embryotoxic damage of metformin and guanylurea in D. rerio by blocking their entrance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In the present work a comprehensive characterization of the hierarchical architecture of the walnut shell (Juglans regia L.) was carried out using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Furthermore, micromechanical properties (hardness, H IT and elastic modulus, E IT ) of plant tissues were evaluated at cell wall level by applying the instrumented indentation technique (IIT). The complex architecture of the material was described in terms of four hierarchical levels (HL): endocarp (H1), plant tissues (H2), plant cells (H3) and cell wall (H4). Our findings revealed that the walnut shell consists of a multilayer structure (sclerenchyma tissue, ST; interface tissue, IT; porous tissue, PT; and flattened parenchyma tissue, FPT), where differences in the microstructure and composition of plant tissues generate parallel gradients along the cross-section. The indentation tests showed a functional gradient with a sandwich-like configuration, i.e., a lightweight and soft layer (PT, H IT  = 0.04 GPa) is located between two dense and hard layers (ST, H IT  = 0.33 GPa; FPT, H IT  = 0.28 GPa); where additionally there is an interface between ST and PT (IT, H IT  = 0.16 GPa). This configuration is a successful strategy designed by nature to improve the protection of the kernel by increasing the strength of the shell. Therefore, the walnut shell can be considered as a functionally graded material (FGM), which can be used as bioinspiration for the design of new functional synthetic materials. In addition, we proposed some structure-property-function relationships in the whole walnut shell and in each of the plant tissues., (Copyright © 2022. Published by Elsevier Ltd.)

This study aimed to evaluate the influence of pH changes on morphometric parameters of casein micelles and a general overview of their conformational structure through microscopy techniques, Raman spectroscopy and multivariate analysis. It was found that casein micelles morphology and protein secondary structure depend strongly upon pH. The changes of arithmetic average roughness (Ra), size, and shape of casein micelles at different pH are properly characterized by atomic force and cryo-transmission electron microscopy. Morphometric changes of casein micelles were correlated correctly with folding and unfolding of casein molecules as evaluated by Raman spectroscopy when the pH was varied. The novelty of this contribution consists in demonstrating that there is a close structure-functionality relationship between the morphometric parameters of proteins and their secondary structure. Knowledge about casein micelles can help improve their use of its diverse applications.

The use of nanoparticles (NPs) in various industries has experienced significant growth due to the advantages they offer, so the increase in their use has generated the continuous discharge of these products in numerous water bodies, which can affect the organisms that inhabit them. Previous studies have shown that Al is capable of producing oxidative stress in aquatic organisms; however, so far the impact of AlNP on hydrobionts is limited. Therefore, the objective of this work was to determine the oxidative stress produced by AlNP in liver, gill and blood of Cyprinus carpio, as well as their bioconcentration factor (BCF) in various tissues. For this purpose, the organisms were exposed to 50 μg L -1 AlNP for 12-96 h. Subsequently, the tissues were obtained and the activity of antioxidant enzymes, oxidative damage to lipids and proteins were determined, and the BCF was calculated for liver, brain, gill and muscle. The results showed alterations in the activity of antioxidant enzymes and increased levels of lipoperoxidation, hydroperoxides and oxidized proteins. When establishing the integrated biomarker response, it was observed that the liver is the most affected organ and these effects are related to the Al content in the tissue. Finally, it was observed that muscle and gills presented a higher BCF, compared to brain and liver. These findings show that AlNP are capable of generating oxidative stress in carp, affecting tissue function and accumulating, which represents an important risk for the health of fish such as common carp., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The objective of this study was to evaluate the effect of the presence of calcium oxalate (CaOx) crystals on the micromechanical properties of sclerenchyma tissue from the pecan nutshell (Carya illinoinensis). The microstructure of the cross-section nutshell was examined using light microscopy (LM) and atomic force microscopy (AFM). Using an instrumented indentation system, indentation tests with maximum loads of 500 mN were made on the biological material where the variables studied were the number of crystals present in the evaluated area and the size of individual crystals. Microscopic analysis revealed that the pecan nutshell consists of sclerenchyma tissue with multiple CaOx crystals randomly distributed throughout the material, exhibiting prismatic shapes and various sizes. The results of the indentation tests showed that the examined areas where there were crystals (1, 2 or up to 3) presented values of hardness and elastic modulus significantly higher (P < 0.05) compared to the sclerenchyma (without crystals). Likewise, there were no significant differences (P > 0.05) between the values of the micromechanical properties of the areas evaluated as a function of the number of crystals. On the other hand, it was observed that the size of the crystals did not show a direct correlation with the mechanical properties evaluated as expected. In conclusion, the biomineralization phenomenon is a successful strategy designed by nature to improve the rigidity of the pecan nutshell, where the CaOx crystals strengthen the structure by increasing the micromechanical properties., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Campylobacter jejuni is a pathogen bacterium that causes foodborne gastroenteritis in humans. However, phenolic compounds extracted from natural sources such as capsicum pepper plant (Capsicum annuum L. var. aviculare) could inhibit the growth of C. jejuni. Therefore, different extracts were prepared using ultrasonic extraction (USE), conventional extraction (CE) and thermosonic extraction (TSE). C. jejuni was then exposed to chili extracts to examine the antimicrobial effect and their growth/death bacterial kinetics were studied using different mathematical models. Atomic force microscopy was applied to investigate the microstructural and nanomechanical changes in the bacteria. Extracts obtained by TSE had the highest phenolic content (4.59 ± 0.03 mg/g of chili fresh weight [FW]) in comparison to USE (4.12 ± 0.05 mg/g of chili FW) and CE (4.28 ± 0.07 mg/g of chili FW). The inactivation of C. jejuni was more efficient when thermosonic extract was used. The Gompertz model was the most suitable mathematical model to describe the inactivation kinetics of C. jejuni. Roughness and nanomechanical analysis performed by atomic force microscopy (AFM) provided evidence that the chili extracts had significant effects on morphology, surface, and the reduced Young's modulus of C. jejuni. The novelty of this work was integrating growth/death bacterial kinetics of C. jejuni using different mathematical models and chili extracts, and its relationship with the morphological, topographic and nanomechanical changes estimated by AFM., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study presents a nanocomposite developed with PVA, multiwall carbon nanotubes (CNTs) doped with nitrogen, and NaDDBS, which change the electrical properties of the polymer and its viscosity to be used in electrospinning process for obtaining mats of nano/macro fibers. The proposed nanocomposite was characterized using Fourier transform-infrared and Raman spectroscopy techniques, confirming the presence of the CNxs immersed in the polymer. High-resolution transmission electron microscopy was used to obtain the micrographs that showed the characteristic interplanar distances of the multiwall CNT in the polymeric matrix, with values of 3.63 Å. Finally, the CNx mats were exposed to various aqueous solutions in a potentiostat to demonstrate the effectiveness of the nanofibers for electrochemical analysis. The CNx-induced changes in the electrical properties of the polymer were identified using cyclic voltammograms, while the electrochemical analysis revealed supercapacitor behavior.

In this study, tomato plants were grown in vitro with and without incorporation of TiO 2 nanoparticles in Murashige and Skoog (MS) growth medium. The aim of this study was to describe the morphological (area and roundness cell) and mechanical (Young's Modulus) change in the different tissue of tomato root, epidermis (Ep), parenchyma (Pa), and vascular bundles (Vb), when the whole plant was exposed to TiO 2 nanoparticles (TiO 2 NPs). light microscopy (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), wavelength dispersive X-ray fluorescence (WDXRF) techniques were used to identify changes into the root cells when TiO 2 NPs were incorporated. TiO 2 NPs incorporation produces changes in the area, roundness, and Young's Modulus of the tomato root. When tomato root is exposed to TiO 2 NPs, the Ep and Vb area size decreases from 260.92 µm 2 to 160.71 µm 2 and, 103.08 µm 2 to 52.13 µm 2 , respectively, compared with the control area, while in Pa tissue the area size was increased considerably from 337.72 mm 2 to 892.96 mm 2 . Cellular roundness was evident in tomato root that was exposed to TiO 2 NPs in the Ep (0.49 to 0.67), Pa (0.63 to 0.79), and Vb (0.76 to 0.71) area zones. Young's Modulus in Pa zone showed a rigid mechanical behavior when tomato root is exposed to TiO 2 NPs (0.48 to 4.98 MPa control and TiO 2 NPs, respectively). Meanwhile, Ep and Vb were softer than the control sample (13.9 to 1.06 MPa and 6.37 to 4.41 MPa respectively). This means that the Pa zone was stiffer than Ep and Vb when the root is exposed to TiO 2 NPs. Furthermore, TiO 2 NPs were internalized in the root tissue of tomato, accumulating mainly in the cell wall and intercellular spaces, with a wide distribution throughout the tissue, as seen in TEM.

The aim of this study was to obtain cellulose and cellulose nanoparticles (CNP) from garlic and agave wastes, as well as elucidating its structure at different scales using microscopy and spectroscopy techniques. Cellulose is isolated by using a sequential extractive process and monitored by CLSM and SEM, while CNP are produced in a high-energy planetary mill. FTIR and XRD confirmed the presence of cellulose type I and CI and D hkl was used to evaluate the size of CNP. The corresponding crystalline structure, d-spacing and angles obtained from crystalline regions of CNP were estimated by TEM and computational simulation. It is shown that the triclinic phase is predominant in G, and a monoclinic conformation in CNP for A. The novelty of this contribution is to demonstrate that the crystalline structure of CNP, extracted from different agro-food wastes, depends on its initial microstructural arrangement (laminar or fibrillar)., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The cuajilote (Parmentiera edulis D.C.) tree produces fibrous fruits with a high content of lignocellulosic compounds. However, this fruit and their fibers have been scarcely studied. For this reason, an integral study of their cellular architecture, physicochemical, micromechanical, and structural properties in two maturity stages were carried out. Physicochemical tests, light, confocal and electron microscopy, microindentation, and X-ray diffraction were used for the characterization of fruit and their fibers. Chemical analysis showed that the unripe fruits have the highest cellulose content (42.17%), but in ripe fruit the cellulose content decreases (32.76%) while lignin content increases from 35.26 to 40.79%, caused by the lignification of the sclerenchyma fibers. Microstructural and micromechanical studies in the different regions of the fruit provided relevant information about its cellular architecture, distribution of lignocellulosic compounds and its role in the micromechanical properties of their fibers. The thickening cell wall of sclerenchyma fibers was caused by the cellular lignification of the ripe fruits. According to the physicochemical and structural studies, cuajilote fibers are comparable to other fibers obtained from crops rich in lignocellulosic compounds. The current study provided new knowledge about the cellular architecture of fruit and criteria for selecting the ripening stage adequate for the extraction of cellulose or lignin. Furthermore, information regarding the micromechanical properties of their fibers and which structural arrangement could be more convenient for mechanical reinforcement of biodegradable materials was obtained., (© 2020 Wiley Periodicals LLC.)

Background: This study describes a promising method for understanding how halophytes adapt to extreme saline conditions and to identify populations with greater resistance. Image and colour analyses have the ability to obtain many image parameters and to discriminate between different aspects in plants, which makes them a suitable tool in combination with genetic analysis to study the plants salt tolerance. To the best of our knowledge, there are no publications about the monitoring of halophytic plants by non-destructive methods for identifying the differences between plants that belong to different maternal salinity environments. The aim is to evaluate the ability of image analysis as a non-destructive method and principal component analysis (PCA) to identify the multiple responses of two S. europaea populations, and to determine which population is most affected by different salinity treatments as a preliminary model of selection., Results: Image analysis was beneficial for detecting the phenotypic variability of two S. europaea populations by morphometric and colour parameters, fractal dimension (FD), projected area (A), shoot height (H), number of branches (B), shoot diameter (S) and colour change (ΔE). S was found to strongly positively correlate with both proline content and ΔE, and negatively with chlorophyll content. These results suggest that proline and ΔE are strongly linked to plant succulence, while chlorophyll decreases with increased succulence. The negative correlation between FD and hydrogen peroxide (HP) suggests that when the plant is under salt stress, HP content increases in plants causing a reduction in plant complexity and foliage growth. The PCA results indicate that the greater the stress, the more marked the differences. At 400 mM a shorter distance between the factorial scores was observed. Genetic variability analysis provided evidence of the differences between these populations., Conclusions: Our non-destructive method is beneficial for evaluating the halophyte development under salt stress. FD, S and ΔE were relevant indicators of plant architecture. PCA provided evidence that anthropogenic saline plants were more tolerant to saline stress. Furthermore, random amplified polymorphic DNA analysis provided a quick method for determining genetic variation patterns between the two populations and provided evidence of genetic differences between them.

Here, different tissue surfaces of tomato root were characterized employing atomic force microscopy on day 7 and day 21 of growth through Young's modulus and plasticity index. These parameters provide quantitative information regarding the mechanical behavior of the tomato root under fresh conditions in different locations of the cross-section of root [cell surface of the epidermis, parenchyma (Pa), and vascular bundles (Vb)]. The results show that the mechanical parameters depend on the indented region, tissue type, and growth time. Thereby, the stiffness increases in the cell surface of epidermal tissue with increasing growth time (from 9.19 ± 0.68 to 13.90 ± 1.68 MPa) and the cell surface of Pa tissue displays the opposite behavior (from 1.74 ± 0.49 to 0.48 ± 0.55); the stiffness of cell surfaces of Vb tissue changes from 10.60 ± 0.58 to 6.37 ± 0.53 MPa, all cases showed a statistical difference (p &lt; 0.05). Viscoelastic behavior dominates the mechanical forces in the tomato root. The current study is a contribution to a better understanding of the cell mechanics behavior of different tomato root tissues during growth.

Oriented immobilization of antibodies on a sensor surface is critical for enhancing both the antigen-binding capacity and the sensitivity of immunosensors. In this study, we describe a strategy to adsorb immunoglobulin G (IgG) anti-Brucella antibodies onto a silicon surface, oriented by protein A obtained from Staphylococcus aureus (SpA). X-ray photoelectron spectroscopy and atomic force microscopy were used to characterize topographically, morphologically, and chemical changes of the sensor functionalization. The activity of the biosensor was assessed by confocal microscopy, scanning electronic microscopy, and bacteria capture assays (BCA). According to the BCA, the efficiency of Brucella abortus detection with the SpA-IgG anti Brucella biosensor was three-fold higher than that of the random orientated IgG anti Brucella biosensor. The limit of detection was 1 × 10 6 CFU/ml. These data show that the orientation of antibodies immobilization is crucial to developing immunosensors for bacterial antigen detection as Brucella spp and improve its sensibility level. Functionalization with protein A increases Brucella detection by an antibody-coated surface. Functionalized silicon surface for Brucella detection was characterized by atomic force microscopy, X-ray photoelectron spectroscopy and confocal microscopy., (© 2019 Wiley Periodicals, Inc.)

In this work, the porosity of the layers of calcified chicken eggshell (vertical crystal layer VCL, palisade layer PL and mammillary layer ML) was evaluated using atomic force microscopy (AFM) and image processing (IP). AFM topographic images were obtained from different locations for each layer and along the cross-section of calcified eggshell. Roughness parameters, surface area values, pore size and shape, surface porosity, area occupied by pores and pore density were obtained from AFM and IP. It was observed that the thickest layer (PL) exhibited the highest degree of porosity (surface porosity = 2.75 ± 1.68%, pore density = 162 ± 60 pores/μm 2 ) when compared to the other two layers. In general, the pores located in all layers ("bubble pores") had circular shape and similar sizes. Measurements revealed a porosity gradient along the cross-section which varied with position, i.e., increasing surface porosity from the VCL towards the region of the PL closer to the ML, and decreasing surface porosity from this location towards the ML innermost surface. This suggests that the calcified eggshell has a sandwich-like structure where porosity may influence gas exchange and mechanical properties. The combination of AFM with IP presented here provides a simple and precise method to study porosity in calcified chicken eggshell, and this methodology could be used to examine other types of porous biological materials., (Copyright © 2018. Published by Elsevier Ltd.)

The morphology and micromechanical properties of the mineral crystals embedded in the pecan nutshell (Carya illinoinensis) were characterized. Qualitative and quantitative morphological analyses carried out revealed that the crystals were comprised of calcium oxalate (CaOx) and have a wide range of sizes, with prismatic shapes, distributed heterogeneously in the sclerenchyma tissue. From indentation tests, it was found that CaOx crystals are stiffer structures compared to stone cells (sclerenchyma tissue), showing hardness and elastic modulus values of 0.53 ± 0.19 GPa and 9.4 ± 1.80 GPa, respectively. Additionally, the values of fracture toughness (0.08 ± 0.02 MPa m 0.5 ) and the brittleness index (9336 m -0.5 ) revealed that these types of structures are extremely brittle. The results obtained suggest that the main function of the CaOx crystals is to provide structural support to tissue. The presented methodology demonstrates the potential of the instrumented indentation technique (IIT) for in situ micromechanical characterization of mineral crystals located in plant tissues., (Copyright © 2018. Published by Elsevier Masson SAS.)

Mango is an important crop worldwide, with a postharvest loss that is huge due to its climacteric behaviour. This study evaluated the softening of Tommy Atkins mangos during the ripening process. Ripening index (RPI) shown a decrease from 9.18 ± 0.14 to 4.75 ± 0.47. The enzymatic activity agreed with physicochemical parameters and with the structural and mechanical changes. Three pectin fractions were isolated from the mango cell wall: water soluble (WSP), chelator soluble (CSP) and diluted alkali soluble (DASP) pectin. The Younǵs modulus (E) of the primary cell wall was evaluated, it decreased from 1.69 ± 1.02 to 0.39 ± 0.16 MPa, which could be attributed to the softening of the fruit. A linear fit correlation between E and RPI was found. X-ray and confocal laser scanning microscopy analysis showed the changes occurred in the mango cell wall structure during maturation. Novelties of current study can be helpful in the use of mango wastes to obtain cellulose., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Worldwide, breast cancer (BrCa) is currently the leading cause of deaths associated to malignant lesions in adult women. Given that some studies have mentioned that peritumoral adipocytes may contribute to breast carcinogenesis, present work sought to quantitative evaluate the morphometry of these cells in a group of adult women. Three thousand six hundred sixty four breast adipocytes, that came from biopsies of a group of adult females with different types of breast carcinomas (ductal, lobular, and mixed) and one with normal tissues, were evaluated through an image analysis (IA) process regarding six morphometric descriptors: area (A), perimeter (P), Feret diameter (F D ), aspect ratio (AR), roundness factor (RF), and fractal dimension of cellular contour (FD C ). Data showed that the adipocytes of the normal tissues group were bigger (A: 3398 ± 2331 µm 2 , P: 239 ± 83 µm, and F D : 79.9 ± 24.5 µm) than those from BrCa samples (A: 2860 ± 1933 µm 2 , P: 214 ± 66 µm, and F D : 73.2 ± 22.5 µm), and presented a more irregular contour (FD C of 1.370 ± 0.037 for normal group and of 1.335 ± 0.049 for the oncologic one). Moreover, it could be accounted that adipocytes of mixed carcinomas were largest (F D : 75.1 ± 22.4 µm) than those of lobular lesions (F D : 61.6 ± 22.6 µm), while the adipocytes of ductal carcinomas were the most oval (AR: 1.421 ± 0.524) and roughest (FD C : 1.324 ± 0.050) cells. IA results suggest that BrCa lesions can be categorized through a quantitative morphometric evaluation of peritumoral adipocytes. These findings could let the development of an analytical tool to help the Pathologist to enhance the accuracy of the oncologic diagnose., (© 2017 Wiley Periodicals, Inc.)

Edible films (EFs) have gained great interest due to their ability to keep foods safe, maintaining their physical and organoleptic properties for a longer time. The aim of this work was to develop EFs based on a chitosan-zein mixture with three different essential oils (EOs) added: anise, orange, and cinnamon, and to characterize them to establish the relationship between their structural and physical properties. The addition of an EO into an EF significantly affected ( p < 0.05) the a* (redness/greenness) and b* (yellowness/blueness) values of the film surface. The EFs presented a refractive index between 1.35 and 1.55, and thus are classified as transparent. The physical properties of EFs with an added EO were improved, and films that incorporated the anise EO showed significantly lower water vapor permeability (1.2 ± 0.1 g mm h -1 m -2 kPa -1 ) and high hardness (104.3 ± 3.22 MPa). EFs with an added EO were able to inhibit the growth of Penicillium sp. and Rhizopus sp. to a larger extent than without an EO. Films' structural changes were the result of chemical interactions among amino acid side chains from zein, glucosamine from chitosan, and cinnamaldehyde, anethole, or limonene from the EOs as detected by a Raman analysis. The incorporation of an EO in the EFs' formulation could represent an alternative use as coatings to enhance the shelf life of food products., Competing Interests: The authors declare no conflict of interest.

The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60-180 min), formic acid concentration (80-95%), temperature (60-80°C), and hydrogen peroxide concentration (2-4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

The objective of this work was to obtain Spirulina (Arthrospira maxima) nanoparticles (SNPs) by using high-impact mechanical milling and to characterize them by electron microscopy and spectroscopy techniques. The milling products were analyzed after various processing times (1-4 h), and particle size distribution and number mean size (NMS) were determined by analysis of high-resolution scanning electron microscopic images. The smallest particles are synthesized after 3 h of milling, had an NMS of 55.6±3.6 nm, with 95% of the particles being smaller than 100 nm. High-resolution transmission electron microscopy showed lattice spacing of ~0.27±0.015 nm for SNPs. The corresponding chemical composition was obtained by energy-dispersive X-ray spectroscopy, and showed the presence of Ca, Fe, K, Mg, Na, and Zn. The powder flow properties showed that the powder density was higher when the average nanoparticle size is smaller. They showed free flowability and an increase in their specific surface area (6.89±0.23 m2/g) up to 12-14 times larger than the original material (0.45±0.02 m2/g). Fourier transform infrared spectroscopy suggested that chemical damage related to the milling is not significant.

Recently, the use of different types of natural fibers to produce paper and textiles from agave plants has been proposed. Agave atrovirens can be a good source of cellulose and lignin; nevertheless, the microstructural changes that happen during delignification have scarcely been studied. The aim of this work was to study the microstructural changes that occur during the delignification of agave fibers by means of microscopy techniques and image analysis. The fibers of A. atrovirens were obtained from leaves using convective drying, milling, and sieving. Fibers were processed using the Acetosolv pulping method at different concentrations of acetic acid; increasing acid concentration promoted higher levels of delignification, structural damage, and the breakdown of fiber clumps. Delignification followed by spectrometric analysis and microstructural studies were carried out by light, confocal laser scanning and scanning electron microscopy and showed that the delignification process follows three stages: initial, bulk, and residual. Microscopy techniques and image analysis were efficient tools for microstructural characterization during delignification of agave fibers, allowing quantitative evaluation of the process and the development of linear prediction models. The data obtained integrated numerical and microstructural information that could be valuable for the study of pulping of lignocellulosic materials.

The use of composite edible films made from biopolymers has attracted interest as a way to reduce pollution and recycling problems; however, the relation between barrier, mechanical and structural properties of the films have been scarcely studied. The aim of this work was to evaluate composite zein-chitosan edible films by applying common nanotechnology tools and to relate the results to zein concentration and film structural changes. Rougher, more elastic, and less hard film structures with better water vapour barrier properties were obtained using larger zein concentrations. Raman spectroscopy exhibited unexpected interactions, as indicated by the disappearance of the thiol groups of cysteine in the zein films and the appearance of O=S=O and C-O-S groups in the blended materials in conjunction with the disappearance of zein ε-amino and -NH2 functional groups in the zein film samples, thereby confirming changes in the blended film structure. Zein concentration presented linear correlations with water vapour permeability (R=-0.978) and film roughness (R=0.929). The composite films presented better barrier and mechanical properties than single ingredient films. This information shows the benefit of using protein-polysaccharide blends to prepare edible films., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The aim of this work is to characterize the microstructure of chitosan and alginate edible films by microscopy techniques and texture image analysis. Edible films were obtained by solution casting and solvent evaporation. The microscopy techniques used in this work were: light, environmental scanning electron and atomic force microscopy. Textural features and fractal dimension were extracted from the images. Entropy and fractal dimension were more useful to evaluate the complexity and roughness of films. The highest values of entropy and fractal dimension corresponded to alginate/chitosan, followed of alginate and chitosan films. An entropy/fractal dimension ratio, proposed here, was useful to characterize the degree of image complexity and roughness of edible films at different magnifications. It was possible to postulate that microscopy techniques combined with texture image analysis are efficient tools to quantitatively evaluate the surface morphology of edible films made of chitosan and alginate., (Copyright © 2011 Elsevier Ltd. All rights reserved.)