Gellan-gum coated gold nanorods: a new tool for biomedical applications

Publicado em "Frontiers in Bioengineering and Biotechnology. Conference Abstract: 10th World Biomaterials Congress"Introduction: Gold nanorods (AuNRs) have been widely studied, in the scope of cancer research and biomedical applications [1]. Their optical properties, easy synthesis and high surface area make AuNRs an outstanding tool for a plethora of applications, such as drug delivery, imaging and tissue engineering [2]. However, before biomedical usage, it is necessary to modify AuNRs surface chemistry, to improve their biocompatibility and stability under biological conditions [3]. One possible approach is the use of biocompatible natural-based polymers that enhance AuNRs performance while allowing the controlled release of drugs/bioactive agents. Herein, we report the successful preparation of a core-shell nanostructure using low-acyl gellan gum (GG) [4], [5] for the coating of AuNRs. Methods: AuNRs were prepared following the seed-mediated growth method [6]. Then, particles were coated with a successive deposition of anionic and cationic polyelectrolytes (poly(acrylic acid) and poly(allylamine hydrochloride), respectively). The pre-coated nanorods were added to a low-acyl gellan gum (GG) solution, previously heated at 90ºC to allow dissolution, and the mixture was stirred overnight at room temperature. The GG-coated AuNRs (AuNR-GG) were characterized by UVvisible spectrometry, zeta potential measurements and transmission electron microscopy (TEM). AuNRs cytotoxicity was accessed in vitro after 1, 3, 7 and 14 days of SaOS-2 cell culture, using an MTS assay. Nanoparticles internalization was confirmed by TEM. In vivo biocompatibility tests were also performed by delivering a solution of AuNRs-GG via tail injection in mice. Results and Discussion: AuNRs were successfully synthesized and coated with a GG shell of approximately 7 nm, as shown in Figure 1. The presence of the GG around AuNRs clearly improved particles stability at different salt and pH conditions, as observed by UV-vis spectroscopy. The in vitro studies using SaOS-2 showed that AuNRs-GG are noncytotoxic. TEM analyses have confirmed that nanoparticles are uptaken by cells and aggregate within cytoplasmic vesicles as depicted in Figure 2. Additionally, in vivo tests suggest that AuNRs are harmless for mice after 24 hours. Conclusion: In this study, AuNRs were individually coated with a gellan gum (GG) shell, resulting in nanoparticles with enhanced stability under different salt concentrations and range of pH’s. Thence, one can conclude that the GG present around the nanoparticles acts as a stabilizer, improving AuNRs stability and biocompatibility. AuNRs-GG have shown noteworthy features and a high potential for further use on biomedical applications including intracellular drug delivery and imaging.QREN (ON.2 – NORTE-01-0124-FEDER-000018) co-financed by North Portugal Regional Operational Program (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)The Portuguese Foundation for Science and Technology (FCT) - SFRH/BD/102710/201

Development & performance assessment of a new ATMP for cartilage tissue engineering

Publicado em "Frontiers in Bioengineering and Biotechnology. Conference Abstract: 10th World Biomaterials Congress"NORTE-07-0202-FEDER-023189 / ARTICULATE - Desenvolvimento de novos produtos e terapias regenerativas para o tratamento de patologias articulares / AD

Finely tuned fiber-based porous structures for bone tissue engineering applications

[Excerpt] Scaffolds developed for bone tissue engineering (TE) must possess specific structural properties to allow neo-tissue formation and integration within the material[1]. Several polymeric systems and processing methodologies have been proposed to develop bone TE scaffolds. Nevertheless, the so far proposed strategies do not fulfil all the requirements for effective bone regeneration. Textile technologies have recently emerged as an industrial route for producing more complex fibre-based porous scaffolds[2]. Silk fibroin (SF) from Bombyx mori has already proved to be a good biomaterial for bone TE[3]. SF-based structures are known for the impressive mechanical properties and biocompatibility, which meet the basic requirements for developing bone TE scaffolds[4],[5]. [...]Portuguese Foundation for Science and Technology (FCT) for the project TISSUE2TISSUE (PTDC/CTM/105703/2008); Investigator FCT program IF/00423/2012 and IF/00411/2013

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Cartilage tissue engineering and regenerative strategies

Human adult articular cartilage is a unique avascular tissue which displays the ability to resist to repetitive compressive stress. However, this connective tissue exhibits slight capacity for intrinsic restoration and, then even injuries or lesions can lead to progressive damage and osteoarthritic joint deterioration. Therefore, the field of cartilage repair continues to expand, bridging the gap between palliative care and chondral defects reconstruction. Tissue engineering strategy, centered on three actors: cells, proteins and scaffolds, received a lot of attention in the aim to develop an articular cartilage regeneration process that will be efficient, simple, and based on global market, costeffective. The current state of cartilage tissue engineering with respect to different cellsources, growth factors and biomaterial scaffolds, as well as the strategies employed in the restoration and repair of damaged articular cartilage will be the focus of this book chapter

Natural-based hydrogels: from processing to applications

Natural-based hydrogels have been widely used for Tissue Engineering and Regenerative Medicine (TERM) as a platform to better mimic the native extracellular matrix of different tissues. Polysaccharides and proteins of natural origin have been functionalized, tuned, and processed used different methods to produce different scaffolds and medical devices. Herein, the recent reports dealing with the application of natural-based hydrogels in TERM strategies are overviewed. Moreover, different methodologies used to process the polymeric hydrogels are also described as well as the most relevant strategies used within the scope of TERM.info:eu-repo/semantics/publishedVersio

Cell culture methods

The restoration of osteochondral defects presents great challenges that have not been fully solved by the current therapies. Therefore, this field continues to expand, bridging the gap between palliative care and defects reconstruction. In the last few years, tissue engineering and regenerative medicine have been offering advanced strategies and some of which have successfully reached clinical application and the market. Beyond the origin and source of cells, the development of culture conditions remains an important step to further clinical applications. Several approaches have been focused on good manufacturing practice (GMP) conditions. The aim is the creation of advanced therapy medicinal products (ATMPs). The up-to-date state of the culture protocols for osteochondral tissue engineering with respect to different cells, growth factors, and biomaterial scaffolds, as well as the strategies employed in clinical trials for the restoration and repair of osteochondral defects, will be the focus of this book chapter.(undefined)info:eu-repo/semantics/publishedVersio

Adherence to treatment in allergic rhinitis using mobile technology. The MASK Study

Background: Mobile technology may help to better understand the adherence to treatment. MASK-rhinitis (Mobile Airways Sentinel NetworK for allergic rhinitis) is a patient-centred ICT system. A mobile phone app (the Allergy Diary) central to MASK is available in 22 countries. Objectives: To assess the adherence to treatment in allergic rhinitis patients using the Allergy Diary App. Methods: An observational cross-sectional study was carried out on all users who filled in the Allergy Diary from 1 January 2016 to 1 August 2017. Secondary adherence was assessed by using the modified Medication Possession Ratio (MPR) and the Proportion of days covered (PDC) approach. Results: A total of 12 143 users were registered. A total of 6 949 users reported at least one VAS data recording. Among them, 1 887 users reported ≥7 VAS data. About 1 195 subjects were included in the analysis of adherence. One hundred and thirty-six (11.28%) users were adherent (MPR ≥70% and PDC ≤1.25), 51 (4.23%) were partly adherent (MPR ≥70% and PDC = 1.50) and 176 (14.60%) were switchers. On the other hand, 832 (69.05%) users were non-adherent to medications (MPR <70%). Of those, the largest group was non-adherent to medications and the time interval was increased in 442 (36.68%) users. Conclusion and clinical relevance: Adherence to treatment is low. The relative efficacy of continuous vs on-demand treatment for allergic rhinitis symptoms is still a matter of debate. This study shows an approach for measuring retrospective adherence based on a mobile app. This also represents a novel approach for analysing medication-taking behaviour in a real-world setting