Electroactive functional microenvironments from bioactive polymers: A new strategy to address cancer.

The present work reports on a new approach based on electroactive microenvironments to mitigate skeletal muscle cancer. For that, piezoelectric films based on poly(vinylidene fluoride) have been applied to evaluate the influence of mechano- and/or electrical stimuli on rhabdomyosarcoma (RMS) proliferation. Human embryonal rhabdomyosarcoma (RD) cells were cultured on PVDF pristine films with different surface charge (non-poled, poled+ and poled-) and magnetic composites (10% and 20% Fe3O4, and 20% CFO filler content) to allow magneto-mechanical and magnetoelectrical stimulation films. Electrospun PVDF pristine (oriented and randomly) and magnetic (10% Fe3O4) fiber mats were also evaluated to take into consideration the morphology effect on cell response. It was found that the mechanical stimuli enhance RMS proliferation whereas the mechano-electrical decreases it. It was also verified that the RD cells proliferate better on randomly oriented fibers, whereas myoblast cells do it better in oriented ones. The obtained results confirm that electroactive microenvironments can be used to develop novel and effective approaches to deal with RMS cancer, that can be extrapolated to others cancer types.

The Prevalence of Visual Impairment and Refractive Errors among a Youth Population in Mozambique: Evidence of the Need for Intervention.

Visual impairment (VI) can significantly interfere in the child's daily activities and quality of life, having a negative effect on their development and learning. The aim of the study was to determine the prevalence of VI and associated demographic factors in students examined during the program "Moçambique te vejo melhor". This study was cross-sectional and retrospective, based on the 2018/19 edition of the program. Eye examinations were performed in secondary school students, aged between 12 and 20 years, of five districts in Nampula province. The examination included visual acuity, non-cycloplegic refraction and assessment of the anterior and posterior segment and ocular adnexa. The prevalence of uncorrected, presenting and best-corrected VI found was 18.3%, 10.8%, and 5.0%, respectively. Refractive error (RE) had a prevalence of 24.7%, and the age groups between 15-17 years and 18-20 years were significantly associated with myopia (with OR: 4.9 and OR: 8.8, respectively), as well as the 11th and 12th grade (OR: 8.1 and OR: 10.7, respectively), and Malema district had association with myopia (ORa: 0.4) and hyperopia (ORa: 0.4 and OR: 0.3) as a protective factor. The prevalence of RE and VI was relatively high, showing the need for greater intervention at the school level.

Hydrogel-based magnetoelectric microenvironments for tissue stimulation.

The development of strategies to mimic the natural environment of tissues with engineered scaffolds remains one of the biggest challenges of tissue engineering. Hydrogels appear as suitable materials for this purpose due to their substantial water content, biocompatibility, and for being able to carry nanomaterials that introduce new functionalities to the hydrogel. The incorporation of magnetically responsive and, in particular, magnetoelectric materials into the hydrogel-based scaffolds are a promising approach for bone tissue engineering applications once it can promote not only tissue regeneration through magnetic to mechanic to electrical conversion/stimuli but also the external control of the scaffold by the application of magnetic fields. This work reports on a new CoFe2O4/ Methacrylated Gellan Gum (GGMA)/poly(vinylidene fluoride) (PVDF) hydrogel-based scaffold with 20 kPa Young's modulus and cell viability superior to 80%. The ≈ 1 µm thick PVDF/CoFe2O4 spheres added to GGMA gel (2 wt.%) exhibit 20 emu.g-1 magnetization saturation, 2.7 kOe magnetic coercivity and ß-phase contents ≈ 78%, leading to a piezoelectric response |d33| of ≈ 22 pC N-1 and a magnetoelectric response of Δ|d33| ≈ 6 pC N-1 at a DC magnetic field of 220 m T, as verified for the CoFe2O4/PVDF spheres with 20 wt.% filler content. Such characteristics allow novel tissue regeneration strategies approaches once CoFe2O4/GGMA/PVDF has a porous 3-D structure, biocompatibility, bioresorbability, and mechanical/electrical dynamic responses that can be triggered by an applied external magnetic field.

New self-assembled supramolecular hydrogels based on dehydropeptides.

Supramolecular hydrogels rely on small molecules that self-assemble in water as a result of the cooperative effect of several relatively weak intermolecular interactions. Peptide-based low molecular weight hydrogelators have attracted enormous interest owing to the simplicity of small molecules combined with the versatility and biocompatibility of peptides. In this work, naproxen, a well known non-steroidal anti-inflammatory drug, was N-conjugated with various dehydrodipeptides to give aromatic peptide amphiphiles that resist proteolysis. Molecular dynamics simulations were used to obtain insight into the underlying molecular mechanism of self-assembly and to rationalize the design of this type of hydrogelators. The results obtained were in excellent agreement with the experimental observations. Only dehydrodipeptides having at least one aromatic amino acid gave hydrogels. The characterization of the hydrogels was carried out using transmission electron microscopy (TEM), circular dichroism (CD), fluorescence spectroscopy and also rheological assays.