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- Molecular Imprinting on Nanozymes for Sensing ApplicationsPublication . Cardoso, Ana Rita; Frasco, Manuela F.; Serrano, Verónica; Fortunato, Elvira; Sales, Maria Goreti FerreiraAs part of the biomimetic enzyme field, nanomaterial-based artificial enzymes, or nanozymes, have been recognized as highly stable and low-cost alternatives to their natural counterparts. The discovery of enzyme-like activities in nanomaterials triggered a broad range of designs with various composition, size, and shape. An overview of the properties of nanozymes is given, including some examples of enzyme mimics for multiple biosensing approaches. The limitations of nanozymes regarding lack of selectivity and low catalytic efficiency may be surpassed by their easy surface modification, and it is possible to tune specific properties. From this perspective, molecularly imprinted polymers have been successfully combined with nanozymes as biomimetic receptors conferring selectivity and improving catalytic performance. Compelling works on constructing imprinted polymer layers on nanozymes to achieve enhanced catalytic efficiency and selective recognition, requisites for broad implementation in biosensing devices, are reviewed. Multimodal biomimetic enzyme-like biosensing platforms can offer additional advantages concerning responsiveness to different microenvironments and external stimuli. Ultimately, progress in biomimetic imprinted nanozymes may open new horizons in a wide range of biosensing applications.
- Photonics in nature and bioinspired designs: sustainable approaches for a colourful worldPublication . Vaz, Raquel; Frasco, Manuela F.; Sales, M. Goreti F.Biological systems possess nanoarchitectures that have evolved for specific purposes and whose ability to modulate the flow of light creates an extraordinary diversity of natural photonic structures. In particular, the striking beauty of the structural colouration observed in nature has inspired technological innovation in many fields. Intense research has been devoted to mimicking the unique vivid colours with newly designed photonic structures presenting stimuli-responsive properties, with remarkable applications in health care, safety and security. This review highlights bioinspired photonic approaches in this context, starting by presenting many appealing examples of structural colours in nature, followed by describing the versatility of fabrication methods and designed coloured structures. A particular focus is given to optical sensing for medical diagnosis, food control and environmental monitoring, which has experienced a significant growth, especially considering the advances in obtaining inexpensive miniaturized systems, more reliability, fast responses, and the use of label-free layouts. Additionally, naturally derived biomaterials and synthetic polymers are versatile and fit many different structural designs that are underlined. Progress in bioinspired photonic polymers and their integration in novel devices is discussed since recent developments have emerged to lift the expectations of smart, flexible, wearable and portable sensors. The discussion is expanded to give emphasis on additional functionalities offered to related biomedical applications and the use of structural colours in new sustainable strategies that could meet the needs of technological development.
- A biomimetic photonic crystal sensor for label-free detection of urinary venous thromboembolism biomarkerPublication . Resende, Sara; Frasco, Manuela F.; Sales, Maria Goreti FerreiraThis work reports a novel label-free sensor combining photonic crystals and molecularly-imprinted polymer materials for targeting a protein in human samples within levels of clinical interest. This concept was applied to detect fibrinopeptide B (FPB) in urine, a biomarker of venous thromboembolism, which is a disease of great concern and demands innovative point-of-care devices for improved diagnosis. The molecularly-imprinted photonic polymer (MIPP) was obtained by tailoring an imprinted polymer on highly ordered silica nanoparticles assembled by vertical deposition. Owing to the hierarchical structure, the resulting MIPP exhibited optical properties that changed upon rebinding of the target analyte, FPB. Thus, the changes in reflectance intensity enabled a rapid and sensitive detection of FPB in human urine. The observed response was linear between 0.2 ng mL−1 and 22 ng mL-1 and showed a limit of detection of 0.13 ng mL-1. These features of the sensing material allow the assessment of urinary FPB at relevant clinical levels. In addition, the sensor was selective for FPB compared to the standard biomarker of venous thromboembolism, D-Dimer. The stability of the material was evidenced by the reusability study, which demonstrated reversibility of the maximum intensity after three cycles of recognition and regeneration. Moreover, the sensor showed good performance for the spiked FPB detection in control human urine. Overall, the application of such label-free sensor offers high selectivity and stability, as well as easy operation. It may constitute an alternative method for non-invasive and real-time detection of various protein biomarkers in point-of-care.