Dynamic Fluorescence Microscopy of Cellular Uptake of Intercalating Model Drugs by Ultrasound-Activated Microbubbles

Microneedle-Assisted Transfersomes as a Transdermal Delivery System for Aspirin

Transdermal drug delivery systems offer several advantages over conventional oral or hypodermic administration due to the avoidance of first-pass drug metabolism and gastrointestinal degradation as well as patients' convenience due to a minimally invasive and painless approach. A novel transdermal drug delivery system, comprising a combination of transfersomes with either solid silicon or solid polycarbonate microneedles has been developed for the transdermal delivery of aspirin. Aspirin was encapsulated inside transfersomes using a "thin-film hydration sonication" technique, yielding an encapsulation efficiency of approximately 67.5%. The fabricated transfersomes have been optimised and fully characterised in terms of average size distribution and uniformity, surface charge and stability (shelf-life). Transdermal delivery, enhanced by microneedle penetration, allows the superior permeation of transfersomes into perforated porcine skin and has been extensively characterised using optical coherence tomography (OCT) and transmission electron microscopy (TEM). In vitro permeation studies revealed that transfersomes enhanced the permeability of aspirin by more than four times in comparison to the delivery of unencapsulated "free" aspirin. The microneedle-assisted delivery of transfersomes encapsulating aspirin yielded 13-fold and 10-fold increases in permeation using silicon and polycarbonate microneedles, respectively, in comparison with delivery using only transfersomes. The cytotoxicity of different dose regimens of transfersomes encapsulating aspirin showed that encapsulated aspirin became cytotoxic at concentrations of ≥100 μg/mL. The results presented demonstrate that the transfersomes could resolve the solubility issues of low-water-soluble drugs and enable their slow and controlled release. Microneedles enhance the delivery of transfersomes into deeper skin layers, providing a very effective system for the systemic delivery of drugs. This combined drug delivery system can potentially be utilised for numerous drug treatments.

Deep Learning-Based Artificial Intelligence to Investigate Targeted Nanoparticles' Uptake in TNBC Cells

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer in women. It has the poorest prognosis along with limited therapeutic options. Smart nano-based carriers are emerging as promising approaches in treating TNBC due to their favourable characteristics such as specifically delivering different cargos to cancer cells. However, nanoparticles' tumour cell uptake, and subsequent drug release, are essential factors considered during the drug development process. Contemporary qualitative analyses based on imaging are cumbersome and prone to human biases. Deep learning-based algorithms have been well-established in various healthcare settings with promising scope in drug discovery and development. In this study, the performance of five different convolutional neural network models was evaluated. In this research, we investigated two sequential models from scratch and three pre-trained models, VGG16, ResNet50, and Inception V3. These models were trained using confocal images of nanoparticle-treated cells loaded with a fluorescent anticancer agent. Comparative and cross-validation analyses were further conducted across all models to obtain more meaningful results. Our models showed high accuracy in predicting either high or low drug uptake and release into TNBC cells, indicating great translational potential into practice to aid in determining cellular uptake at the early stages of drug development in any area of research.

A fiber optoacoustic emitter with controlled ultrasound frequency for cell membrane sonoporation at submillimeter spatial resolution

Focused ultrasound has attracted great attention in minimally invasive therapeutic and mechanism studies. Frequency below 1 MHz is identified preferable for high-efficiency bio-modulation. However, the poor spatial confinement of several millimeters and large device diameter of ∼25 mm of typical sub-MHz ultrasound technology suffered from the diffraction limit, severely hindering its further applications. To address it, a fiber-based optoacoustic emitter (FOE) is developed, serving as a miniaturized ultrasound point source, with sub-millimeter confinement, composed of an optical diffusion layer and an expansion layer on an optical fiber. By modifying acoustic damping and light absorption performance, controllable frequencies in the range of 0.083 MHz-5.500 MHz are achieved and further induce cell membrane sonoporation with frequency dependent efficiency. By solving the problem of compromise between sub-MHz frequency and sub-millimeter precision via breaking the diffraction limit, the FOE shows a great potential in region-specific drug delivery, gene transfection and neurostimulation.

Combined Confocal Microscope and Brandaris 128 Ultra-High-Speed Camera

Controlling microbubble-mediated drug delivery requires the underlying biological and physical mechanisms to be unraveled. To image both microbubble oscillation upon ultrasound insonification and the resulting cellular response, we developed an optical imaging system that can achieve the necessary nanosecond temporal and nanometer spatial resolutions. We coupled the Brandaris 128 ultra-high-speed camera (up to 25 million frames per second) to a custom-built Nikon A1R+ confocal microscope. The unique capabilities of this combined system are demonstrated with three experiments showing microbubble oscillation leading to either endothelial drug delivery, bacterial biofilm disruption, or structural changes in the microbubble coating. In conclusion, using this state-of-the-art optical imaging system, microbubble-mediated drug delivery can be studied with high temporal resolution to resolve microbubble oscillation and high spatial resolution and detector sensitivity to discern cellular response. Combining these two imaging technologies will substantially advance our knowledge on microbubble behavior and its role in drug delivery.

Acoustic Characterization of the CLINIcell for Ultrasound Contrast Agent Studies

Ultrasound contrast agents consist of gas-filled coated microbubbles that oscillate upon ultrasound insonification. Their characteristic oscillatory response provides contrast enhancement for imaging and has the potential to locally enhance drug delivery. Since microbubble response depends on the local acoustic pressure, an ultrasound compatible chamber is needed to study their behavior and the underlying drug delivery pathways. In this study, we determined the amplitude of the acoustic pressure in the CLINIcell, an optically transparent chamber suitable for cell culture. The pressure field was characterized based on microbubble response recorded using the Brandaris 128 ultrahigh-speed camera and an iterative processing method. The results were compared to a control experiment performed in an OptiCell, which is conventionally used in microbubble studies. Microbubbles in the CLINIcell responded in a controlled manner, comparable to those in the OptiCell. For frequencies from 1 to 4 MHz, the mean pressure amplitude was -5.4 dB with respect to the externally applied field. The predictable ultrasound pressure demonstrates the potential of the CLINIcell as an optical, ultrasound, and cell culture compatible device to study microbubble oscillation behavior and ultrasound-mediated drug delivery.

Drug permeation and metabolism in Mycobacterium tuberculosis: Prioritising local exposure as essential criterion in new TB drug development

Anti-tuberculosis (TB) drugs possess diverse abilities to penetrate the different host tissues and cell types in which infecting Mycobacterium tuberculosis bacilli are located during active disease. This is important since there is increasing evidence that the respective "lesion-penetrating" properties of the front-line TB drugs appear to correlate well with their specific activity in standard combination therapy. In turn, these observations suggest that rational efforts to discover novel treatment-shortening drugs and drug combinations should incorporate knowledge about the comparative abilities of both existing and experimental anti-TB agents to access bacilli in defined physiological states at different sites of infection, as well as avoid elimination by efflux or inactivation by host or bacterial metabolism. However, while there is a fundamental requirement to understand the mode of action and pharmacological properties of any current or experimental anti-TB agent within the context of the obligate human host, this is complex and, until recently, has been severely limited by the available methodologies and models. Here, we discuss advances in analytical models and technologies which have enabled investigations of drug metabolism and pharmacokinetics (DMPK) for new TB drug development. In particular, we consider the potential to shift the focus of traditional pharmacokinetic-pharmacodynamic analyses away from plasma to a more specific "site of action" drug exposure as an essential criterion for drug development and the design of dosing strategies. Moreover, in summarising approaches to determine DMPK data for the "unit of infection" comprising host macrophage and intracellular bacillus, we evaluate the potential benefits of including these analyses at an early stage in the preclinical drug development algorithm. © 2018 IUBMB Life, 70(9):926-937, 2018.