Acoustic Sensing and Ultrasonic Drug Delivery in Multimodal Theranostic Capsule Endoscopy

Video capsule endoscopy (VCE) is now a clinically accepted diagnostic modality in which miniaturized technology, an on-board power supply and wireless telemetry stand as technological foundations for other capsule endoscopy (CE) devices. However, VCE does not provide therapeutic functionality, and research towards therapeutic CE (TCE) has been limited. In this paper, a route towards viable TCE is proposed, based on multiple CE devices including important acoustic sensing and drug delivery components. In this approach, an initial multimodal diagnostic device with high-frequency quantitative microultrasound that complements video imaging allows surface and subsurface visualization and computer-assisted diagnosis. Using focused ultrasound (US) to mark sites of pathology with exogenous fluorescent agents permits follow-up with another device to provide therapy. This is based on an US-mediated targeted drug delivery system with fluorescence imaging guidance. An additional device may then be utilized for treatment verification and monitoring, exploiting the minimally invasive nature of CE. While such a theranostic patient pathway for gastrointestinal treatment is presently incomplete, the description in this paper of previous research and work under way to realize further components for the proposed pathway suggests it is feasible and provides a framework around which to structure further work

Ultrasound mediated delivery of quantum dots from a capsule endoscope to the gastrointestinal wall

Biologic drugs, defined as therapeutic agents produced from or containing components of a living organism, are of growing importance to the pharmaceutical industry. Though oral delivery of medicine is convenient, biologics require invasive injections because of their poor bioavailability via oral routes. Delivery of biologics to the small intestine using electronic delivery with devices that are similar to capsule endoscopes is a promising means of overcoming this limitation and does not require reformulation of the therapeutic agent. The efficacy of such capsule devices for drug delivery could be further improved by increasing the permeability of the intestinal tract lining with an integrated ultrasound transducer to increase uptake. This paper describes a novel proof of concept capsule device capable of electronic application of focused ultrasound and delivery of therapeutic agents. Fluorescent markers, which were chosen as a model drug, were used to demonstrate in-vivo delivery in the porcine small intestine with this capsule. We show that the fluorescent markers can penetrate the mucus layer of the small intestine at low acoustic powers when combining microbubbles with focussed ultrasound. These findings suggest that the use of focused ultrasound together with microbubbles could play a role in the oral delivery of biologic therapeutics

Ultrasound mediated delivery of quantum dots from a proof of concept capsule endoscope to the gastrointestinal wall

Biologic drugs, defined as therapeutic agents produced from or containing components of a living organism, are of growing importance to the pharmaceutical industry. Though oral delivery of medicine is convenient, biologics require invasive injections because of their poor bioavailability via oral routes. Delivery of biologics to the small intestine using electronic delivery with devices that are similar to capsule endoscopes is a promising means of overcoming this limitation and does not require reformulation of the therapeutic agent. The efficacy of such capsule devices for drug delivery could be further improved by increasing the permeability of the intestinal tract lining with an integrated ultrasound transducer to increase uptake. This paper describes a novel proof of concept capsule device capable of electronic application of focused ultrasound and delivery of therapeutic agents. Fluorescent markers, which were chosen as a model drug, were used to demonstrate in vivo delivery in the porcine small intestine with this capsule. We show that the fluorescent markers can penetrate the mucus layer of the small intestine at low acoustic powers when combining microbubbles with focused ultrasound during in vivo experiments using porcine models. This study illustrates how such a device could be potentially used for gastrointestinal drug delivery and the challenges to be overcome before focused ultrasound and microbubbles could be used with this device for the oral delivery of biologic therapeutics

A novel peptide-enhanced drug delivery system for squamous cell oesophageal carcinoma

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand in fulfilment of the requirements for the degree of Doctor of Philosophy. University of the Witwatersrand, Department of Pharmacy and Pharmacology, Johannesburg, South Africa. 2017.Cancer has been described as one of the major and leading causes of death worldwide. By the year 2030, it has been postulated that over 21.4 million new cases of cancer are anticipated, with 17 million cancer deaths annually and a total of 75 million people living with cancer within five years of diagnosis. Chemotherapy is the main therapeutic intervention for treating people living with oesophageal squamous cell carcinoma (OSCC). However, drug resistance, non-targeted delivery, sub-optimal dosage at disease sites and side effects on healthy cells have rendered it inefficient and ineffective in combating the disease even after combination chemotherapy. The paradigm shift in cancer nanomedicine employs the use of short functional peptides and ligands, conjugated to the surfaces of nanoparticles, for direct and active drug delivery systems in in vitro and in vivo assays. Smart and intelligent nanosystems remain a proactive and promising treatment alternative to circumvent the anomalies of current convectional cancer chemotherapeutics and enhance their delivery for optimal anti-tumoral effects. Based on these modalities, the conceptualization, design, optimization and characterization of a smart peptide-enhanced ligand-functionalized nano-construct – referred to herein as a PEL nanosystem – capable of encapsulating, targeting and controlling the release of endostatin (ENT), was fabricated in this study. Physicochemical parameters that characterized the design of a smart nano-construct in cancer therapy including satisfactory size, shape and surface properties, cellular uptake and internalization by tumor cells, low cellular toxicity to healthy cells and enhanced anti-tumoral activity of the encapsulated drug informed the fabrication of the PEL nanosystem. An optimized PEG-PEI-CHT nano-conjugate was developed as predicted by the Box–Behnken design model and surface-functionalized with Ly-P-1, PENT and FA as targeting moieties. Fourier Transform Infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) analysis confirmed the successful grafting of the nano-conjugates while Transmission Electron Microscopy (TEM) and Dynamic Light Scathering (DLS) analyses confirmed the synthesis of PEL nanoparticles with an average size less than 100nm. Scanning Electron Microscopy (SEM) results confirmed the morphology of the PEL nanosystem to be spherical with rough surfaces due to the attachments of the functionalized moieties. The release profile of the PEL nanosystem showed increased release of ENT at the acidic tumor micro-environment than observed at the physiological pH of healthy cells. Interestingly, the smart PEL nanosystem exhibited an enhanced targeted release of ENT for anti-tumoral effects on KYSE-30 cells relative to the unmodified nanosystem. The PEL nanosystem loaded with ENT showed a pragmatic inhibition of potent angiogenic factors including cell proliferation, nuclear apoptosis and necrosis, cell migration and invasion, as well as reduced expressions of both VEGF-C and MMP2 proteins as molecular makers for anti-angiogenesis. Athymic nude mice induced with OSSC xenografts showed a dramatic reduction in tumor volume with increased necrotic arears after treatment with the PEL ENT-loaded nanoparticles relative to the control. Overall, detailed in vitro, ex vivo cellular and in vivo experiments validated the fabricated PEL nanoparticulate systems as efficient delivery vehicles of ENT for enhancing its anti-tumoral activity by targeting the angiogenic pathway in KYSE-30 cells as presented in this study. While ENT was selected as a peptide-based anti-cancer model drug in this study due to its broad spectrum anti-angiogenic activities and limitations, the novel PEL nanosystem can be employed to incorporate alternative cancer chemotherapeutics for enhanced on-site delivery for an optimum therapeutic response in cancer therapy.LG201

Development of a 1D phased ultrasonic array for intravascular sonoporation

Error on title page – year of award is 2021.Sonoporation represents a promising approach to increase targeted drug delivery efficiency by facilitating transport of therapeutic agents to the target tissue with the use of ultrasound. However, most of the current research in sonoporation is performed with external ultrasonic transducers, which hinders the applicability of the therapeutic procedure for treatment of conditions situated deeper into the patient’s body, such as liver or intestinal tumours. This Thesis presents the development process of a miniature-sized 1-3 connectivity piezocomposite 1D phased array for intracorporeal sonoporation. The device was to be incorporated into a capsule or catheter and hence the primary design constraint was the reduced size of the piezoelectric element, which was limited to 2.5 mm in width and 12 mm in length. To meet the needs of the intended application, resonance frequencies of 1.5 MHz and 3.0 MHz were considered. A simulation framework was developed for optimization of the miniature array in relation to the peak negative pressure attained at the focus to mitigate the low power output associated with the limited device dimensions. This was implemented through a multiparametric sweep of the 1-3 piezocomposite geometry-related parameters. Devices made with PZT-5H and PMN-29%PT were evaluated. The optimization algorithm was used to determine specifications for phased array designs based on the two materials and the two resonance frequencies. The 1.5 MHz devices comprised 24 elements and the 3.0 MHz ones had 32 elements. The piezocomposites were manufactured using the dice and fill technique and electroded using a novel method of electrode deposition employing spin coating of Ag ink. Subsequently, the prototype devices were driven with a commercial array controller and characterized with a calibrated needle hydrophone in a scanning tank. Two simulation profiles based on finite element analysis and time extrapolation were developed to model the acoustic beams from the arrays, which were compared and calibrated with experimental data for focal distances between 5 mm and 10 mm and beam steering angles from 0° to 40°. The results showed that modelling could be employed reliably for therapeutic planning. Both the 1.5 MHz and the 3.0 MHz, PZT-5H arrays were tested in vitro and shown to induce and control sonoporation of a human epithelial colorectal adenocarcinoma cell layer. Finally, a 24 element, 1.5 MHz, PZT-5H array was implemented in a 40 mm long by 11 mm diameter tethered, biocompatible capsule intended for in vivo operation. The device was characterized in the scanning tank for steering angles in the range 0° to 56° and focal distances between 4.0 mm and 5.7 mm, and the measured beam profiles were correlated with the simulation framework. The capsule will be tested in future ex-vivo and in-vivo experiments on insulin absorption through porcine small bowel by means of sonoporation.Sonoporation represents a promising approach to increase targeted drug delivery efficiency by facilitating transport of therapeutic agents to the target tissue with the use of ultrasound. However, most of the current research in sonoporation is performed with external ultrasonic transducers, which hinders the applicability of the therapeutic procedure for treatment of conditions situated deeper into the patient’s body, such as liver or intestinal tumours. This Thesis presents the development process of a miniature-sized 1-3 connectivity piezocomposite 1D phased array for intracorporeal sonoporation. The device was to be incorporated into a capsule or catheter and hence the primary design constraint was the reduced size of the piezoelectric element, which was limited to 2.5 mm in width and 12 mm in length. To meet the needs of the intended application, resonance frequencies of 1.5 MHz and 3.0 MHz were considered. A simulation framework was developed for optimization of the miniature array in relation to the peak negative pressure attained at the focus to mitigate the low power output associated with the limited device dimensions. This was implemented through a multiparametric sweep of the 1-3 piezocomposite geometry-related parameters. Devices made with PZT-5H and PMN-29%PT were evaluated. The optimization algorithm was used to determine specifications for phased array designs based on the two materials and the two resonance frequencies. The 1.5 MHz devices comprised 24 elements and the 3.0 MHz ones had 32 elements. The piezocomposites were manufactured using the dice and fill technique and electroded using a novel method of electrode deposition employing spin coating of Ag ink. Subsequently, the prototype devices were driven with a commercial array controller and characterized with a calibrated needle hydrophone in a scanning tank. Two simulation profiles based on finite element analysis and time extrapolation were developed to model the acoustic beams from the arrays, which were compared and calibrated with experimental data for focal distances between 5 mm and 10 mm and beam steering angles from 0° to 40°. The results showed that modelling could be employed reliably for therapeutic planning. Both the 1.5 MHz and the 3.0 MHz, PZT-5H arrays were tested in vitro and shown to induce and control sonoporation of a human epithelial colorectal adenocarcinoma cell layer. Finally, a 24 element, 1.5 MHz, PZT-5H array was implemented in a 40 mm long by 11 mm diameter tethered, biocompatible capsule intended for in vivo operation. The device was characterized in the scanning tank for steering angles in the range 0° to 56° and focal distances between 4.0 mm and 5.7 mm, and the measured beam profiles were correlated with the simulation framework. The capsule will be tested in future ex-vivo and in-vivo experiments on insulin absorption through porcine small bowel by means of sonoporation