Browsing by Author "Martingo, Maria Lima"
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- Insect chitosan bioinspired approach for haemodialysis treatmentPublication . Martingo, Maria Lima; Borges, Sandra Cristina Ferreira; Silva, Sara Isabel Macedo Baptista da; Pintado, Maria Manuela EstevezChronic kidney disease (CKD) is characterised by a continuous decline in kidney function, often persisting for months or even years. The prevalence of CKD has been increasing over the years, representing a growing public health challenge and is expected to become the fifth leading cause of death by 2040. For patients with end-stage kidney disease (ESKD), renal replacement therapy (RRT), either through dialysis (haemodialysis, HD, and peritoneal dialysis, PD) or kidney transplantation, are crucial but expensive treatments. However, for some ESKD patients’ transplantation may not be appropriate due to medical contraindications, making dialysis the appropriate approach in these situations. In fact, both dialysis modalities, HD or PD, can offer similar long-term results. This thesis presents an innovative exploration into the extraction and application of insect chitosan (Tenebrio molitor) for biomedical purposes, specifically targeting HD. Initially, the potential of insect-derived chitosan as a sustainable and effective alternative to traditional sources (i.e. marine crustaceans) is demonstrated. Efficient extraction methods were developed (totalling between 6 h and 12 h), producing chitosan with physical and chemical properties comparable to commercial chitosan from crustaceans. Firstly, chitin was efficiently isolated from T. molitor through deproteinisation and demineralisation, with yields of approximately 5%. Subsequently, chitosan was obtained from the extracted chitin using an accelerated process, resulting in yields of between 65.0 ± 0.8% and 79.3 ± 0.8%. Characterisation using Fourier transform infrared spectroscopy (FTIR) confirmed structural similarities with commercial chitosan and degrees of deacetylation in the 73 - 75% range. The bioactive properties of chitosan obtained from T. molitor, including antimicrobial and antioxidant activities, were evaluated. All the microorganisms tested (Escherichia coli, Staphylococcus aureus, Candida albicans, Staphylococcus epidermidis and Pseudomonas aeruginosa) were inhibited, exhibiting minimum lethal concentrations between 2 and 8 mg/mL, confirming the antimicrobial activity of the extracted chitosan. In addition, chitosan showed antioxidant activity in the range of 60 to 65 µmol Trolox equivalent/g, suggesting its viability for various medical applications. This dissertation also developed a chitosan-based membrane (CH - M) specifically for HD purposes, culminating in a proof-of-concept phase for haemodialysis, focusing on the evaluation of diffusion and retention permeability parameters. The permeation characteristics of CH-M for urea and albumin were studied in vitro to assess their suitability as HD membranes. Urea was permeable to values of over 70 per cent and albumin was fully retained. This comprehensive approach ensured the exploration and development of an innovative, bio-inspired solution for HD, with an emphasis on sustainability and innovation, although further studies will have to be carried out on biocompatibility, treatment simulation duration, porosity, permeability and haemocompatibility tests.
- A new vision upon hemodialysis: a shift from synthetic to sustainable chitosan membranesPublication . Martingo, Maria Lima; Baptista-Silva, Sara; Pintado, Manuela; Borges, SandraThe article provides a comprehensive review of chronic kidney disease (CKD), covering its epidemiology, pathophysiology, diagnosis, and management. It highlights CKD's increasing prevalence globally and its significant impact on public health due to its association with cardiovascular diseases and progression to end-stage kidney disease. The article delves into the diagnostic criteria, including the use of glomerular filtration rate (GFR) and albuminuria levels, and outlines the stages of CKD to facilitate early detection and management. It also discusses renal replacement therapies (RRT) such as dialysis and transplantation, comparing hemodialysis (HD) and peritoneal dialysis (PD) in terms of efficiency, complications, and quality of life impacts.The transition towards sustainable dialysis involves the innovative integration of chitosan, a biopolymer into membrane technology. Current synthetic membranes, though functional, fall short in biocompatibility and sustainability. Chitosan's introduction aims to mitigate these issues by harnessing its advantageous biological and eco-friendly properties. Leveraging chitosan not only addresses environmental concerns by providing a sustainable alternative but also exploits the full potential of its properties to revolutionize RRT. The shift towards chitosan-enriched membranes represents a significant stride in advancing dialysis treatment, focusing on patient safety, environmental sustainability, and the effective management of CKD. This approach underscores the importance of innovation in healthcare, specifically in the development of dialysis technologies that prioritize both patient welfare and environmental sustainability.