The treatment of epidermal wounds, particularly chronic wounds, is one of the most ubiquitous medical challenges and has imposed a considerable financial burden on the global health care system. Several factors in epidermal wounds lead to severe medical conditions among which infection comprises a large number of mortalities. To tackle this issue, great efforts have been made in the last decades to incorporate antimicrobial agents into wound dressings in order to inhibit microorganism colonization. Additionally, various wound monitoring systems have been developed to detect and track infections using different indicators such as bacterial by-products. However, the integration of these infection sensors with wound dressings – most of which have benefited from electrochemical detectors – has been a major bottleneck due to the electrode failure in the wound environment and the need for electrical power supply. Other approaches have focused on the development of point-of-care devices that simplify the detection of infection. This study aims to address the aforementioned challenge by developing a multifunctional hydrogel-based wound dressing – made of alginate 1.5% (w/v) – for on-site infection monitoring via colourimetric and image processing methods. Taking advantage of wound acidity as an indicator of bacterial infection, the developed wound dressing was composed of an array of pH sensors, fabricated by 3-dimensional (3D) bioprinting. Brilliant Yellow and cabbage juice as two pH-responsive dyes were immobilized in the pH sensors to facilitate a wireless wound monitoring. In this system, Brilliant Yellow afforded a higher accuracy in image processing while cabbage juice provided a better visual observation of the wound condition. The functionality of the developed dressing in detecting bacterial infection was evaluated via an ex-vivo test on pig skin samples, infected by Pseudomonas aeruginosa, and the presence of bacteria was detected within 30 minutes after the placement of the dressings on the skin samples. Moreover, the inclusion of gentamicin-loaded components into the wound dressing facilitated the inhibition of bacterial growth, which was evaluated in vitro on the same strain of bacteria. In this experiment, 2 mg/ml of gentamicin in the hydrogel led to the eradication of P. aeruginosa. This incorporation of antibiotic delivery along with the simple colourimetric infection detection holds a great promise for managing acute and chronic wounds by inhibition of bacterial growth and monitoring infection in real-time without a need for dressing removal. / Graduate / 2018-08-16

Healthcare-associated infections present an escalating worldwide issue, further intensified by the emergence of antimicrobial resistance and the spread of pathogens on surfaces. Current infection prevention methods have shown limited effectiveness, leading to several health issues, an overuse of antibiotics, and a continuous threat of surface recontamination. In response, extensive research has focused on bioinspired omniphobic smart coatings that effectively reduce the contact area available for pathogen attachment, achieved through an increase in surface roughness and apparent surface energy. This thesis introduces a new class of an omniphobic spray-coating, featuring hierarchical structured polydimethylsiloxane (PDMS) microparticles coated with gold nanoparticles, encompassing primary microscale (~0.23 𝜇m) and secondary nanoscale (~5 nm) buckyball and labyrinth wrinkles. This substrate-independent coating efficiently repels a wide range of liquids, including pathogens, even under harsh conditions like high temperatures, ultraviolet (UV) exposure, and abrasions. Repellency tests comparing coated and uncoated gloves revealed that uncoated gloves spread contamination to 50 secondary surfaces, while coated gloves transferred fewer bacteria and viruses to just three and two surfaces, respectively. The investigation extended to the coating's biocidal capabilities, incorporating gold nanoparticles functionalized with mercapto-silane to create a "Repel and Kill" coating. This process initiates chemisorption through thiol-gold bonding, allowing for the formation of diverse surface structures, including three-dimensional self-assembly, multilayers, and island structures. These modifications significantly enhance the roughness and hydrophobicity of the gold nanoparticles, amplifying their biocidal effectiveness. The wrinkled structure of PDMS contribute to repellency, while the functionalized gold nanoparticles play a crucial role in the antimicrobial property. This enhancement was evident in the antibacterial tests, which exhibited an immediate 99.90% reduction in bacterial adhesion for both MRSA and Pseudomonas aeruginosa (P. aeruginosa), followed by an additional 99.70% and 99.90% reduction in bacterial growth after 8 hours for MRSA and P. aeruginosa, respectively. Moreover, the coating's antiviral properties were confirmed, demonstrating a 98% reduction in the transfer of the bacterial virus Phi6. Recognizing the role of hospital fabrics as potential reservoirs for infection transmission, primarily due to their ability to sustain bacterial growth for extended periods, especially in the presence of bodily fluids, we took further steps to modify the wrinkled PDMS microparticles. This involved the incorporation of silver nanoparticles, capped with a positively charged ligand known as branched polyethyleneimine (bPEI). Additionally, we integrated a colorimetric sensor, giving rise to the "Repel, Kill, and Detect" smart coating. The transition of color from blue to green-yellow provided a tangible indicator of contamination detection based on the acidic mileu of the biofilms. To evaluate its realworld effectiveness, we conducted simulations of infection transmission in hospital environments, resulting in a remarkable reduction in pathogen adhesion from urine and feces by 99.88% and 99.79%, respectively, compared to uncoated fabrics. To further enhance the validation of our results, we employed a powerful deep learning network architecture, that determined whether the surfaces are contaminated or safe. In the face of evolving health challenges, this coating emerges as a resilient and adaptable solution, promising to enhance overall safety and alleviate the burden of infectious diseases. / Thesis / Doctor of Engineering (DEng) / The prolonged survival of pathogens on surfaces, significantly highlighted by the COVID-19 global pandemic, has intensified the urgency of addressing contamination on high-touch surfaces. Engineered surface coatings with repellent properties have emerged as a long-lasting and health-conscious solution for infection prevention and control. In this thesis, we introduce a new class of multifunctional engineered coatings featuring hierarchical structures adorned with biocidal nanoparticles and an integrated colorimetric sensor. We comprehensively investigate these coatings' multifunctional capabilities to repel, exterminate, and detect contaminants. Through specific characterization tests involving a wide range of pathogens, including viruses, bacteria, and fungi, within complex biological fluids like urine and feces, this research culminates in the development of surface coatings equipped with both antimicrobial and pathogen-sensing capabilities. In addition to advancing our understanding of surface hierarchy and chemical modifications for repellency and biocidal activity, this thesis yields insights into the dynamics of biofouling and pathogen transfer, with the overarching goal of reducing pathogen transmission via surfaces.

Cryptosporidium is a genus of apicomplexan unicellular epicellular parasite with worldwide distribution causing watery diarrhea in humans and animals. The life cycle is completed in one host, where Cryptosporidium parasitizing epithelial cells of gastrointestinal tract and in birds can cause disease of respiratory or urogenital tract. Course of disease depends on condition of immune system. For immunodeficient individuals could be life threatening. One of problems especially in developing countries is early and correct diagnostic, particularly no effective treatment currently exist. The aim of this thesis was to compare efficiency of immunochromatographic tests in samples stored under different conditions. The comparison of sensitivity and specificity of these tests with molecular and microscopic techniques was also performed. Additionaly, suitability of immunochromatographic tests for detection of active infection during prepatent period was evaluated. The theoretic part includes general information about Cryptosporidium. Its taxonomy, cycle of evolution or transmission and course of disease. Using of immunochromatographic test is also mentioned. No differences in sensitivity of used immunochromatographic tests was observed in this thesis. The detection rate for most of tests was 200 oocyst per sample. The presence of coproantigen is depend upon presence of oocysts in a sample. False negative results of immunochromatographic assays was caused by i) low concentration of oocysts in a sample (sensitivity) or ii) antibodies in used test don´t react with antigen of Cryptosporidium spp. (specificity). Results of this thesis show that combination of immunochromatographic tests and other techniques is convenient. During prepatent period is not possible to detect specific DNA, antigen or oocysts of Cryptosporidium. The active infection could not be distinguish from passage of oocysts using of immunochromatographic assays even if PCR is also used.