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On the progress of hydrogel-based 3D printing: Correlating rheological properties with printing behaviour

Publication . Bom, Sara; Ribeiro, Ricardo; Ribeiro, Helena; Santos, Catarina; Marto, Joana

One of the exciting future directions in the 3D printing field is the development of innovative personalized smart constructions for bio-applications, including drug delivery, namely high-throughput drug screening and customized topical/oral administration of pharmaceuticals, as well as tissue engineering. In this context, hydrogels have emerged as a promising material that, when combined with extrusion 3D printing, allow the creation of soft-material structures with defined spatial locations, that can be printed at room temperature and customized by tuning the geometric design and/or the formulation components. Thus, the efficacy and quality of such vehicles is dependent on formulation, design, and printing process parameters. However, hydrogel inks are often designed and characterized using different methods and this lack of uniformity impairs. Characterization techniques are usually arbitrary and differ among research groups, challenging the inference of possible conclusions on hydrogel behaviour and potential applications. Therefore, to properly analyse the potential of a particular hydrogel ink formulation, we review, for the first time, the most frequently employed characterization procedures, from rheological approaches to printing parameters and settings, and discuss their relevance, limitations and drawbacks, and highlight future perspectives. Overall, to accelerate the development of high-quality 3D constructs, comprehensive characterization protocols for both pre-printing and printing assays should be adopted. Furthermore, their transversal adoption could serve as a boost in terms of quality requirements and regulatory aspects.

2022-03Journal article

Open access

Overview of Cosmetic Regulatory Frameworks around the World

Publication . Ferreira, Mariana; Matos, Ana; Couras, Ana; Marto, Joana; Ribeiro, Helena

To ensure safety and efficacy, cosmetic products are regulated and controlled worldwide. However, the regulatory approaches of each country may be significantly different and impact the competitiveness and economic viability of the industry. This work presents an updated review and comparison of regulatory requirements from the European Union, United States of America, Canada, Japan, People’s Republic of China and Brazil. It outlines contents such as the definition, classification and categorization of cosmetics, pre-market requirements, ingredients management, general labelling requirements, regulation of claims concerning advertisement and commercial practices, increase of animal testing and marketing bans on cosmetic products. Furthermore, it weighs the impact of regulatory differences on the safety and accessibility of these products in the mentioned regions.

2022-06Journal article

Open access

Potential therapeutic of olive oil industry by-products in skin health: a review

Publication . Nunes, Andreia; Marto, Joana; Gonçalves, Lídia; Martins, Ana Margarida; Fraga, Carmo; Ribeiro, Helena

Olea europaea L. is one of the most important fruit trees in the Mediterranean countries due to its products, olive oil and table olives. However, the olive oil extraction industry produces large amounts of by-products, such as olive pomace, leaves and olive mill wastewater, which are considered harmful to the environment, having negative impacts on soil, aquatic and air ecosystems. The olive oil industry by-products are a major ecological issue mainly due to their phenolic components, such as oleuropein, hydroxytyrosol and tyrosol. However, olive oil industry by-products can be recovered, treated and studied for their health-promoting properties, holding great potential for the cosmetic and pharmaceutical industries. Furthermore, the recovery and treatment processes contribute to an efficient waste management and sustainability of the olive oil industry, leading to important economic benefits. The phenolic compounds extracted and obtained from these by-products present numerous health properties and can be used as antioxidant, photoprotector, anti-inflammatory and/or antimicrobial agents in wellness and therapeutics of the skin. This review highlights issues related to olive oil industry by-products and then proceeds to discuss how their beneficial biological activities make them reusable, particularly their high positive impact in treating skin disorders.

2021-10-12Journal article

Restricted access

Antioxidant-Loaded Mucoadhesive Nanoparticles for Eye Drug Delivery: A New Strategy to Reduce Oxidative Stress

Publication . Cordeiro, Sandra; Silva, Beatriz; Martins, Ana; Ribeiro, Helena; Gonçalves, Lídia; Marto, Joana

There are several approaches to treat ocular diseases, which can be invasive or non-invasive. Within the non-invasive, new pharmaceutical strategies based on nanotechnology and mucoadhesive polymers are emerging methodologies, which aim to reach an efficient treatment of eye diseases. The aim of this work was the development of novel chitosan/hyaluronic acid nanoparticle systems with mucoadhesive properties, intended to encapsulate antioxidant molecules (e.g., crocin) aiming to reduce eye oxidative stress and, consequently, ocular disease. An ultraviolet (UV) absorber molecule, actinoquinol, was also added to the nanoparticles, to further decrease oxidative stress. The developed nanoparticles were characterized and the results showed a mean particle size lower than 400 nm, polydispersity index of 0.220 ± 0.034, positive zeta potential, and high yield. The nanoparticles were also characterized in terms of pH, osmolality, and viscosity. Mucoadhesion studies involving the determination of zeta potential, viscosity, and tackiness, showed a strong interaction between the nanoparticles and mucin. In vitro release studies using synthetic membranes in Franz diffusion cells were conducted to unravel the drug release kinetic profile. Ex vitro studies using pig eye scleras in Franz diffusion cells were performed to evaluate the permeation of the nanoparticles. Furthermore, in vitro assays using the ARPE-19 (adult retinal pigment epithelium) cell line showed that the nanoparticles can efficiently decrease oxidative stress and showed low cytotoxicity. Thus, the developed chitosan/hyaluronic acid nanoparticles are a promising system for the delivery of antioxidants to the eye, by increasing their residence time and controlling their delivery.

2021-02-19Journal article

Open access

Investigations of Olive Oil Industry By-Products Extracts with Potential Skin Benefits in Topical Formulations

Publication . Nunes, Andreia; Gonçalves, Lídia; Marto, Joana; Martins, Ana; Silva, Alexandra N.; Pinto, Pedro; Martins, Marta; Fraga, Carmo; Ribeiro, Helena

The by-products of olive oil industry are a major ecological issue due to their phenolic content, highly toxic organic load, and low pH. However, they can be recovered and reused, since their components have antioxidant, anti-inflammatory, and photoprotector properties. In this work, oil-in-water creams containing three different olive oil industry by-products extracts were produced without the use of organic solvents. First, the extracts were thoroughly characterized in vitro for cytotoxicity, inhibition of skin enzymes, and antioxidant and photoprotection capacities. Safety studies were then performed, including ocular and skin irritation tests, ecotoxicity evaluation, and in vivo Human Repeat Insult Patch Test. The results obtained in this initial characterization supported the incorporation of the extracts in the cream formulations. After preparation, the creams were characterized for their organoleptic, physicochemical, droplet size and rheological properties, and microbial contamination. The results showed that all formulations were semi-solid creams, with stable pH, compatible with the skin, without microbial contamination, and with the expected droplet size range. The rheological analysis showed shear-thinning behavior with yield stress, with the viscosity decreasing with increasing shear rate. The oscillatory results suggest that the creams have a strong network structure, being easily rubbed into the skin. Finally, compatibility, acceptability and antioxidant efficacy were evaluated in vivo, in human volunteers. No adverse reactions were observed after application of the formulations on skin and the cream with the highest concentrations of phenolic compounds showed the highest antioxidant efficiency. In conclusion, the results suggest that olive oil industry by-products extracts have valuable properties that favor their re-use in the cosmetic industry. The example presented here showed their successful incorporation into creams and their impact in these formulations’ appearance, pH, and rheological performance, as well as their in vivo compatibility with skin and antioxidant efficiency.

2021-03Journal article

Open access