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Dr Styliani Totti

Research Fellow
MEng, PhD
+44 (0)1483 684601
34 BC 02

My publications


M Prescott, J Mitchell, Stella Totti, Judy Lee, Eirini Velliou, Madeleine Bussemaker (2017)Sonodynamic therapy combined with novel anti-cancer agents, sanguinarine and ginger root extract: Synergistic increase in toxicity in the presence of PANC-1 cells in vitro., In: Ultrasonics Sonochemistry40(B)pp. 72-80 Elsevier

The presence of ultrasound-induced cavitation in sonodynamic therapy (SDT) treatments has previously enhanced the activity and delivery of certain sonosensitisers in biological systems. The purpose of this work was to investigate the potential for two novel anti-cancer agents from natural derivatives, sanguinarine and ginger root extract (GRE), as sonosensitisers in an SDT treatment with in vitro PANC-1 cells. Both anti-cancer compounds had a dose-dependent cytotoxicity in the presence of PANC-1 cells. A range of six discreet ultrasound power-frequency configurations were tested and it was found that the cell death caused directly by ultrasound was likely due to the sonomechanical effects of cavitation. Combined treatment used dosages of 100 μM sanguinarine or 1mM of GRE with 15 s sonication at 500 kHz and 10 W. The sanguinarine-SDT and GRE-SDT treatments showed a 6% and 17% synergistic increase in observed cell death, respectively. Therefore both sangunarine and GRE were found to be effective sonosensitisers and warrant further development for SDT, with a view to maximising the magnitude of synergistic increase in toxicity.

Stella Totti, Mark C. Allenby, Susana Brito Dos Santos, Athanasios Mantalaris, Eirini Velliou (2018)A 3D bioinspired highly porous polymeric scaffolding system for in vitro simulation of pancreatic ductal adenocarcinoma, In: RSC Advances8pp. 20928-20940 Royal Society of Chemistry

Pancreatic ductal adenocarcinoma is an aggressive disease with an extremely low survival rate. This is due to the (i) poor prognosis and (ii) high resistance of the disease to current treatment options. The latter is partly due to the very complex and dense tissue/tumour microenvironment of pancreatic cancer, which contributes to the disease’s progression and the inhibition of apoptotic pathways. Over the last years, advances in tissue engineering and the development of three-dimensional (3D) culture systems have shed more light into cancer research by enabling a more realistic recapitulation of the niches and structure of the tumour microenvironment. Herein, for the first time, 3D porous polyurethane scaffolds were fabricated and coated with fibronectin to mimic features of the structure and extracellular matrix present in the pancreatic cancer tumour microenvironment. The developed 3D scaffold could support the proliferation of the pancreatic tumour cells, which was enhanced with the presence of fibronectin, for a month, which is a significantly prolonged in vitro culturing duration. Furthermore, in situ imaging of cellular and biomarker distribution showed the formation of dense cellular masses, the production of collagen-I by the cells and the formation of environmental stress gradients (e.g. HIF-1α) with similar heterogeneity trends to the ones reported in in vivo studies. The results obtained in this study suggest that this bioinspired porous polyurethane based scaffold has great potential for in vitro high throughput studies of pancreatic cancer including drug and treatment screening.

Priyanka Gupta, Stella Totti, Pedro A. Pérez-Mancera, Eleanor Dyke, Andrew Nisbet, Giuseppe Schettino, Roger Webb, Eirini Velliou (2019)Chemoradiotherapy screening in a novel biomimetic polymer based pancreatic cancer model, In: RSC Advances9(71)pp. 41649-41663 Royal Society of Chemistry

Pancreatic Ductal Adenocarcinoma (PDAC) is a deadly and aggressive disease with a very low survival rate. This is partly due to the resistance of the disease to currently available treatment options. Herein, we report for the first time the use of a novel polyurethane scaffold based PDAC model for screening the short and relatively long term (1 and 17 days post-treatment) responses of chemotherapy, radiotherapy and their combination. We show a dose dependent cell viability reduction and apoptosis induction for both chemotherapy and radiotherapy. Furthermore, we observe a change in the impact of the treatment depending on the time-frame, especially for radiation for which the PDAC scaffolds showed resistance after 1 day but responded more 17 days post-treatment. This is the first study to report a viable PDAC culture in a scaffold for more than 2 months and the first to perform long-term (17 days) post-treatment observations in vitro. This is particularly important as a longer time-frame is much closer to animal studies and to patient treatment regimes, highlighting that our scaffold system has great potential to be used as an animal free model for screening of PDAC.

R Garriga, Izabela Jurewicz, S Seyedin, Niki Bardi, Styliani Totti, B Matta‐ Domjan, Eirini Velliou, Mohammed Alkhorayef, VL Cebolla, JM Razal, Alan Dalton, E Muñoz (2017)Multifunctional, Biocompatible and pH-Responsive Carbon Nanotube- and Graphene Oxide/Tectomer Hybrid Composites and Coatings, In: Nanoscale9pp. 7791-7804 Royal Society of Chemistry

Here we present a route for non‐covalent functionalization of carboxylated multi‐wall carbon nanotubes and graphene oxide with novel two‐dimensional peptide assemblies. We show that self‐assembled amino‐terminated biantennary and tetraantennary oligoglycine peptides (referred to as tectomers) effectively coat carboxylated multi‐walled carbon nanotubes and also strongly interact with graphene oxide due to electrostatic interactions and hydrogen bonding as the driving force, respectively. The resulting hybrids can be made into free‐standing conducting composites or applied in the form of thin, pH‐switchable bioadhesive coatings onto graphene oxide fibers. Monitoring of cell viability of pancreatic cell lines, seeded on those CNT hybrids, show that they can be used as two‐ and three‐dimensional scaffolds to tissue engineer tumour models for studying ex vivo the tumour development and response to treatment. This highly versatile method in producing pH‐responsive hybrids and coatings offers an attractive platform for a variety of biomedical applications and for the development of functional materials such as smart textiles, sensors and bioelectronic devices.

Stella Totti, Keng Wooi Ng, Lorraine Dale, Guoping Lian, Tao Chen, Eirini G. Velliou (2019)A novel versatile animal-free 3D tool for rapid low-cost assessment of immunodiagnostic microneedles, In: Sensors and Actuators B: Chemical296126652pp. 1-8 Elsevier

Microneedle devices offer minimally invasive and rapid biomarker extraction from the skin. However, the lack of effective assessment tools for such microneedle devices can delay their development into useful clinical applications. Traditionally, the microneedle performance is evaluated i) in vivo, using animal models, ii) ex vivo, on excised human or animal skin or iii) in vitro, using homogenised solutions with the target antigen to model the interstitial fluid. In vivo and ex vivo models are considered the gold-standard approach for the evaluation of microneedle devices because of their structural composition, however they do exhibit limitations. More specifically, they have limited availability and they present batch-to-batch variations depending on the skin origin. Furthermore, their use rises ethical concerns regarding compliance with the globally accepted 3Rs principle of reducing the use of animals for research purposes. At the same time, in vitro models fail to accurately mimic the structure and the mechanical integrity of the skin tissue that surrounds the interstitial fluid. In this study, we introduce for the first time an animal-free, mechanically robust, 3D scaffold that has great potential as an accurate in vitro evaluation tool for immunodiagnostic microneedle devices. More specifically, we demonstrate, for the first time, successful extraction and detection of a melanoma biomarker (S100B) using immunodiagnostic microneedles in the 3D culture system. Melanoma cells (A375) were cultured and expanded for 35 days in the highly porous polymeric scaffold followed by in situ capture of S100B with the microneedle device. Scanning electron microscopy showed a close resemblance between the 3D scaffold and human skin in terms of internal structure and porosity. The microneedle device detected S100B in the scaffold (with a detection pattern similar to the positive controls), while the biomarker was not detected in the surrounding liquid supernatants. Our findings demonstrate the great potential of this animal-free 3D tool for rapid and low-cost evaluation of microneedle devices.

Rachel E. Smith, Stella Totti, Eirini Velliou, Paola Campagnolo, Suzanne M. Hingley-Wilson, Neil I. Ward, John R. Varcoe, Carol Crean (2019)Development of a novel highly conductive and flexible cotton yarn for wearable pH sensor technology, In: Sensors and Actuators B: Chemical287pp. 338-345 Elsevier

The simple and effective approach of “dipping and drying” cotton yarn in a dispersion of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) and multi-walled carbon nanotubes (MWCNT) resulted in the development of a highly conductive and flexible cotton fibres. Subsequent polyaniline (PANi) deposition yielded electrodes with significant biocompatible and antibacterial properties that could be fabricated (alongside quasi-reference electrodes) into solid-state wearable pH sensors, which achieve rapid, selective, and Nernstian responses (-61 ± 2 mV pH-1) over a wide pH range (2.0 – 12.0), even in a pH-adjusted artificial sweat matrix. This development represents an important progression towards the realisation of real-time, on-body, wearable sensors.

Brigitta Matta-Domjan, Alice King, Stella Totti, Csaba Matta, George Dover, Patricia Martinez, Anvar Zakhidov, Roberto La Ragione, Hugo Macedo, Izabela Jurewicz, Alan Dalton, Eirini Velliou (2017)Biophysical interactions between pancreatic adenocarcinoma cell lines and pristine carbon nanotube substrates: Potential application for pancreatic cancer tissue engineering, In: Journal of Biomedical Materials Research Part B-Applied Biomaterials106(5)pp. 1637-1644 Wiley

Novel synthetic biomaterials able to support, direct tissue growth and retain cellular phenotypical properties are promising building blocks for the development of tissue engineering platforms for accurate and fast therapy screening for cancer. The aim of this study is to validate an aligned, pristine multi-walled carbon nanotube (CNT) platform for in vitro studies of pancreatic cancer as a systematic understanding of interactions between cells and these CNT substrates is lacking. Our results demonstrate that our CNT scaffolds -which are easily tuneable to form sheets/fibres- support growth, proliferation and spatial organisation of pancreatic cancer cells, indicating their great potential in cancer tissue engineering.

Stella Totti, SI Vernardis, Lisiane Meira, PA Pérez-Mancera, E Costello, W Greenhalf, D Palmer, J Neoptolemos, A Mantalaris, Eirini Velliou (2017)Designing a bio-inspired bio-mimetic in vitro system for the optimisation of ex vivo studies of pancreatic cancer, In: Drug Discovery Today22(4)pp. 690-701 Elsevier

Pancreatic cancer is one of the most aggressive and lethal human malignancies. Drug therapies and radiotherapy are used for treatment as adjuvants to surgery, but outcomes remain disappointing. Advances in tissue engineering point that three-dimensional cultures can reflect the in vivo tumour micro-environment and can guarantee a physiological distribution of oxygen, nutrients and drugs, therefore, being promising low cost tools for therapy development. In this work we review crucial elements, i.e., structural and environmental, that should be considered for an accurate design of an ex vivo platform for studies of pancreatic cancer. Furthermore, we propose environmental stress response biomarkers as platform readouts for the efficient control and further prediction of the pancreatic cancer response to the environmental and treatment input.

Mona N. Sweilam, Sarah F. Cordery, Stella Totti, Eirini G. Velliou, Paola Campagnolo, John R. Varcoe, M. Begoña Delgado-Charro, Carol Crean (2020)Textile-based non-invasive lithium drug monitoring: a proof-of-concept study for wearable sensing, In: Biosensors and Bioelectronics150111897 Elsevier

Flexible wearable chemical sensors are emerging tools which target diagnosis and monitoring of medical conditions. One of the potential applications of wearable chemical sensors is therapeutic drug monitoring for drugs that have a narrow therapeutic range such as lithium. We have investigated the possibility of developing a fibre-based device for non-invasive lithium drug monitoring in interstitial fluid. A flexible cotton-based lithium sensor was coupled with a carbon fibre-based reference electrode to obtain a potentiometric device. In vitro reverse iontophoresis experiments were performed to extract Li+ from under porcine skin by applying a current density of 0.4 mA cm-2 via two electrodes. Carbon fibre-based reverse iontophoresis electrodes were fabricated and used instead of a conventional silver wire-based version and comparable results were obtained. The fibre-based Li+ sensor and reference electrodes were capable of determining the Li+ concentration in samples collected via reverse iontophoresis and the results compared well to those obtained by ion chromatography. Additionally, biocompatibility of the used materials have been tested. Promising results were obtained which confirm the possibility of monitoring lithium in interstitial fluid using a wearable sensor.