Novel dual imaging-antimicrobial photodynamic therapy probe SeNBD-van is a promising alternative to conventional antibiotics in the treatment against gram-positive bacteria. It successfully labels and identifies gram-positive bacteria and is capable of selectively killing such bacteria, even those with existing multi-resistances to antibiotics in as little at 20 min. It maintains its high efficacy even in complex environments such as biofilms and skin models, demonstrating great value and potential as an alternative to current methods of management of infections.
Fluorescence imaging and ‘smart probes’ are an emerging point-of-care platform for microbial detection. This article proposes a proof-of-concept frugal fluorescence imaging system for the detection of bacteria such as Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. In this work, we investigate the capability of a trans-illuminating fluorescence imaging system to detect bacteria using a low-cost raspberry pi single board computer and a high-quality camera. This system is capable of producing high quality fluorescence and transmission images of bacterial samples with submicron resolution. We demonstrate the capabilities of the system to produce these images in conjunction with low-cost lens-based imaging optics.
Nikola Krstajić, Bethany Mills, Ian Murray, Adam Marshall, Dominic Norberg, Thomas Craven, Philip Emanuel, Tushar Choudhary, Gareth O. Williams, Emma Scholefield, Ahsan Akram, Andrew Davie, Nik Hirani, Annya Bruce, Anne Moore, Mark Bradley, Kevin Dhaliwal
A highly sensitive, modular three-color fluorescence endomicroscopy imaging platform spanning the visible to near-infrared (NIR) range is demonstrated. Light-emitting diodes (LEDs) were sequentially pulsed along with the camera acquisition to provide up to 20 frames per second (fps) three-color imaging performance or 60 fps single color imaging. The system was characterized for bacterial and cellular molecular imaging in ex vivo human lung tissue and for bacterial and indocyanine green imaging in ex vivo perfused sheep lungs. A practical method to reduce background tissue autofluorescence is also proposed. The platform was clinically translated into six patients with pulmonary disease to delineate healthy, cancerous, and fibrotic tissue autofluorescent structures. The instrument is the most broadband clinical endomicroscopy system developed to date (covering visible to the NIR, 500 to 900 nm) and demonstrates significant potential for future clinical utility due to its low cost and modular capability to suit a wide variety of molecular imaging applications.
Optical fibre based endoscopes are increasingly used for imaging and sensing within the human body without navigational guidance of the miniaturised fibre probe. Meanwhile, other medical device placement is a standard procedure in clinic. We demonstrate successful imaging of optical device location with centimetre resolution in clinically relevant models, in a realistically lit environment, achieved through the detection of early arriving photons with a time resolved single photon detector array. This prototype has been developed within the UK-EPSRC Proteus project, moving advanced research technologies towards clinical implementation.
Short (~100ps) laser pulses are transmitted from the tip of the endoscope at 785nm in the “optical window” where attenuation is less severe in clinical scenarios. Most of the photons that pass through tissue undergo much scattering from the disordered tissue structures providing only low accuracy determination of the location of the light source. However, some photons probabilistically undergo less scattering, travelling through the medium in an almost straight line without a much extended path. Such photons exit the body sooner than the highly scattered light.
A camera based upon a 32 × 32 array of Single Photon Avalanche Diodes (SPADs) made with CMOS technology is used to image the small number photons exiting the tissue. The time resolution capabilities of such a single photon detector (50ps time bin resolution, 200ps jitter) allow observation of the photon arrival times simultaneously for all 1024 pixels of the imaging array. Photon arrival statistics distinguish the early arriving photons from the highly scattered light, revealing the endoscope location. Scattered photon arrivals peak at delays of multiple nanoseconds due to the thick tissue samples. The progression of light through complex scattering structures can be observed.
Normal fluorescent room lighting has distinct emission peaks. Appropriate choice of operating wavelength between these spectral features, combined with aggressive filtering, allows operation in normal fluorescent lighting. This compact packaged system is demonstrated in a normally lit room to determine optical endomicroscope location in a whole ventilated ovine lung as well as tissue models including bone structure. At the limit of capabilities of this prototype, demonstration through an entire human torso is shown to be possible.
System improvements and the potential of the next generation prototype in development will be discussed. This offers the potential for real time (sub second) imaging of device location with a portable system for application in standard medical procedures, such as catheter insertion. The avoidance of the need to confirm device placement with X-ray imaging has potential to decrease disruption to procedures throughout clinical practice.
We present a multifunctional endoscope capable of imaging, fluid delivery and fluid sampling in the alveolar space. The endoscope consists of an imaging fibre bundle fabricated from cost effective OM1 PCVD graded index preforms made for the telecommunications market. These low-cost fibres could potentially make our endoscope disposable after a single use. The performance of our low-cost imaging fibre bundle is shown to be comparable to the current commercial state-of-the-art. The imaging fibre bundle is packaged alongside two channels for the delivery and extraction of fluids. The fluid delivery channels can be used to deliver fluorescent smart probes for the detection of pathogens and to perform a targeted alveolar lavage without the removal of the imaging fibre as is currently standard procedure. Our endoscope is fully biocompatible and with an overall outer diameter of 1.4 mm allowing it to fit into the standard working channel of a bronchoscope. We demonstrate the use of our endoscope in ex-vivo human lungs. We show alveolar tissue and bacterial imaging over two wavelength bands 520 nm – 600 nm and 650 nm – 750 nm both commonly used for bacterial smart probe detection.
In healthy humans, the physiological state in the distal lung alveolar acinar units is tightly regulated by normal homeostatic mechanisms. Pulmonary abnormalities such as chronic obstructive pulmonary disease, that are characterized by recurrent cycles of inflammation and infection involving dense infiltration by myeloid derived peripheral blood cells, may result in significant perturbation of the homeostatic baselines of physiology in addition to host tissue damage. Therefore, the ability to quantify and monitor physiology (e.g. pH, glucose level, oxygen tension) within the alveolar acinar units would provide a key biomarker of distal lung innate defence. Although in vitro modeling of fundamental biological processes show remarkable sensitivity to physiological aberrations, little is known about the physiological state of the distal lung due to the inability to concurrently access the alveolar sacs and perform real-time sensing. Here we report on previously unobtainable measurements of alveolar pH using a fiber-optic optrode and surface enhanced Raman spectroscopy (SERS) and show that alveolar pH changes in response to ventilation. The endoscope-deployable optrode consisted of para-mercaptobenzoic acid functionalized 150 nm gold nanoshells located at the distal end, and an asymmetric dual-core optical fiber designed for spatially separated optical pump delivery and SERS signal collection in order to circumvent the unwanted Raman signal originating from the fiber itself. We demonstrate a ~ 100-fold increase in SERS signal-to-fiber background ratio and pH sensing at multiple sites in the respiratory acinar units of a whole ex vivo ovine lung model with a measurement accuracy of ± 0.07 pH units.
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