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Photodynamic therapy (PDT) has been applied in clinical treatment of tumors for a long time. However, insufficient supply of pivotal factors including photosensitizer (PS), light, and oxygen in tumor tissue dramatically reduces the therapeutic efficacy of PDT. Nanoparticles have received an influx of attention as drug carriers, and recent studies have demonstrated their promising potential to overcome the obstacles of PDT in tumor tissue. Physicochemical optimization for passive targeting, ligand modification for active targeting, and stimuli-responsive release achieved efficient delivery of PS to tumor tissue. Various trials using upconversion NPs, two-photon lasers, X-rays, and bioluminescence have provided clues for efficient methods of light delivery to deep tissue. Attempts have been made to overcome unfavorable tumor microenvironments via artificial oxygen generation, Fenton reaction, and combination with other chemical drugs. In this review, we introduce these creative approaches to addressing the hurdles facing PDT in tumors. In particular, the studies that have been validated in animal experiments are preferred in this review over proof-of-concept studies that were only performed in cells., Highlights • Successful photodynamic therapy in tumors has been inhibited by obstacles including insufficient amount of photosensitizer, light attenuation, and unfavorable tumor microenvironmrnt. • Until now, various nanoparticles have been developed and used for tumor-targeted photodynamic therapy. • The nanpparticles showed potential to overcome the obstacles by efficient supply of photosensitizers, light, and oxygen.

In the era of food delivery and grocery delivery startups, traffic crashes associated with light delivery vehicles have increased significantly. Since the number of these crashes is increasing, it ...

Nanobubbles (NBs) have recently gained interest in cancer imaging and therapy due to the fact that nanoparticles with the size range of 1-1000 nm can extravasate into permeable tumor types through the enhanced permeability and retention (EPR) effect. However, the therapeutic study of NBs was only limited to drug delivery or cavitation. Herein, we developed ultrasound-evoked massive NB explosion to strikingly damage the surrounding cancer. The dual-function agent allows synergistic mechanical impact and photodynamic therapy of the tumors and enhances imaging contrast. Moreover, the mechanical explosion improved the light delivery efficiency in biological tissue to promote the effect of photodynamic therapy. Under ultrasound/photoacoustic imaging guidance, we induced on-the-spot bubble explosion and photodynamic therapy of tumors at a depth of centimeters in vivo. The mechanical impact of the explosion can enhance delivery of the photosensitizers. Ultrasound explicitly revealed the cancer morphology and exhibited fast NB perfusion. Generated mechanical damage and release of mixture agents demonstrated remarkable synergetic anticancer effects on deep tumors. This finding also offers a new approach and insight into treating cancers.

Over the past few decades, optical waveguides have been increasingly used in wearable/implantable devices for on-body sensing. However, conventional optical waveguides are stiff, rigid, and brittle. A mismatch between conventional optical waveguides and complex biointerfaces makes wearable/implantable devices uncomfortable to wear and potentially unsafe. Soft and stretchable polymer optical waveguides not only inherit many advantages of conventional optical waveguides (e.g., immunity to electromagnetic interference and without electrical hazards) but also provide a new perspective for solving the mismatch between conventional optical waveguides and complex biointerfaces, which is essential for the development of light-based wearable/implantable sensors. In this review, polymer optical waveguides' unique properties, including flexibility, biocompatibility and biodegradability, porosity, and stimulus responsiveness, and their applications in the wearable/implantable field in recent years are summarized. Then, we briefly discuss the current challenges of high optical loss, unstable signal transmission, low manufacturing efficiency, and difficulty in deployment during implantation of flexible polymer optical waveguides, and propose some possible solutions to these problems.

The purpose of this study was to optimize the light delivery method in a prostate photoacoustic imaging system. A three dimensional (3D) optical model of the human prostate was developed, and the optical energy distribution in the prostate was estimated via three-dimensional Monte Carlo simulation. Then, the feasibility of prostate photoacoustic imaging (PAI) using two endoscopic light delivery methods was studied. Photoacoustic pressure generation and the corresponding photoacoustic images had been obtained and the comparisons were made between each other. Also, the results of cylinder diffusing light source with different lengths were compared. After that, phantom experiment was carried out to validate the simulation results. Our results would be significant in the optimizing photoacoustic imaging system for an accurate diagnosis of prostate cancer.

Aiming at elevating Scenedesmus obliquus biofilm growth from the perspectives of CO2 transfer enhancement and light delivery optimization, a membrane-based photobioreactor with built-in optical fib...

Light is a physical phenomenon that is very important to human life, and has been investigated in its nature, behaviour and properties throughout human history although the most impressive improvements in the use of light in human activities, and of course in medicine, began just two centuries ago. However, despite the enormous progress in diagnosis, therapy and surgery to assess health and treat diseases, the delivery of light sources in vivo remains a challenge. In this regard, several strategies have been developed to overcome this drawback, the most interesting of which is the involvement of ultrasound. In this review, the authors examine how ultrasound may improve light delivery in vivo with a special emphasis on one of the most intriguing ultrasound-mediated phenomena called sonoluminescence, which is the conversion of mechanical ultrasound energy into light.

Photoacoustic imaging (PAI, also called optoacoustic imaging) combines light excitation and ultrasound detection for deep-tissue imaging with light absorption contrast. PAI can map the distribution of endogenous chromophores such as oxy-hemoglobin, deoxy-hemoglobin, lipids, water, and melanin. PAI performs especially well for structural and functional imaging of blood vessels. Its centimeter-deep imaging depth and ultrasound-defined resolution make it well suited for clinical application, where systems employing a linear array ultrasound probe are most commonly used due to simplicity, flexibility, and easy integration with standard ultrasonic imaging. The existing linear array based imaging systems typically employ optical fiber bundles for light delivery, such a scheme enjoys mechanical flexibility, optical stability, and simple light coupling. However, major drawbacks associated with fiber illumination include suboptimal transmission efficiency and a lack of control of the illumination pattern. Articulated arms provide an alternative light delivery option which potentially offer high transmission efficiency, stable and flexible operation, and low cost. Despite its wide applications in cosmetology, articulated arms for light delivery were understudied in the PAI community. In this paper, we reported the fabrication and experimental evaluation of an articulated arm specifically designed for linear-array-based PAI. Without losing the flexibility provided by the linear probe. Moreover, the articulated arm can be equipped with spatial positioning devices to perform three-dimensional reconstructions.

For the past three decades, laser use has been investigated, mainly on implant applications, as well as hard and soft tissue processing on orthopedics. However, despite significant technological advances and achievements in Biophotonics, lasers have yet to emerge as a successful tool for hard-tissue manipulation (e.g., osseous tissue). Indeed, a careful search in relevant literature reveals a limited number of laser-based clinical applications in orthopedics, except for the low-level laser therapy applications. In this review article, we give a brief overview of the biophysical mechanisms of bone tissue and biocompatible implants laser surgery and, in parallel, we summarize some specific pre-clinical and clinical laser applications in orthopedics. Taking into consideration the complexity of laser-based applications in inhomogeneous musculoskeletal biostructures and/or implants, it is justified to state that applying laser radiation is still an open field of multidisciplinary research before performing interventions in clinical praxis. The evidence from this study indicates the need for more experimental and theoretical studies regarding light transport on soft and hard tissues, in order to further enhance safe and efficient laser applications in orthopedics. This undoubtedly implies the need for developing modern light delivery devices for laser surgery, by means of implementing robotic guidance, specialized for medical procedures on various anatomic structures. The aforementioned studies could eventually revolutionize the clinical applications of laser technology in orthopedics.

The light-adjustable lens is the first Food and Drug Administration (FDA)-approved product from an entirely new category of intraocular lenses (IOLs). The 3-piece foldable silicone light-adjustable lens is implanted through a small incision after phacoemulsification. A slit-lamp-based digital light delivery device is used to adjust and then lock-in the IOL power during the first postoperative month. Up to 4.5 diopters (D) of cylindrical or spherical adjustment can be achieved. This should offer significant advantages in difficult IOL power calculation cases, such as postrefractive eyes. In addition to achieving better refractive accuracy, an adjustable IOL will now allow patients to test and elect a different refractive target postoperatively. This paradigm shift will change how cataract patients choose their refractive objectives, and how ophthalmologists will be able to achieve them. For example, adjustable IOLs may increase the popularity of pseudophakic monovision and bilateral same-day sequential surgery. For those electing adjustable IOL, preoperative patient counseling will change and certain pre- and intraoperative technologies, such as intraoperative aberrometry and digital astigmatic axis marking, would become superfluous.

A key assumption of optogenetics is that light only affects opsin-expressing neurons. However, illumination invariably heats tissue, and many physiological processes are temperature-sensitive. Commonly used illumination protocols increased the temperature by 0.2–2 °C and suppressed spiking in multiple brain regions. In the striatum, light delivery activated an inwardly rectifying potassium conductance and biased rotational behavior. Thus, careful consideration of light-delivery parameters is required, as even modest intracranial heating can confound interpretation of optogenetic experiments. Optogenetics has revolutionized neuroscience, but intracranial illumination can cause off-target effects. Owen et al. identify a temperature-sensitive potassium current that modulates neuronal activity and behavior independent of opsin expression.

An optimized hand-held photoacoustic and ultrasound probe suitable for endo-cavity tumor subsurface imaging was designed and evaluated. Compared to previous designs, the prototype probe, consisting of four 1 mm multi-mode optical fibers attached with 1.5 mm diameter ball-shaped fiber tips sandwiched between a transvaginal ultrasound transducer and a custom-made sheath, demonstrated a higher light output and better beam homogeneity on tissue subsurface. The output power and fluence profile were simulated for different design parameters. A camera recorded fluence profiles through calibrated intralipid solution at various imaging depths. The light delivery efficiency was experimentally compared with and without the ball lenses, based on ex-vivo imaging of human colorectal cancer and in-vivo imaging of a palmar vein proximal to the human wrist. The simulations and experiments demonstrated that ball-shaped fiber tip design can achieve homogeneous fluence distribution on tissue subsurface with acceptable light output efficiency, suggesting its clinical potential for in-vivo endo-cavity imaging. Keywords: Photoacoustic imaging, Optimized light delivery probe, Ball-shaped fiber tip, Adenocarcinoma

Understanding the neural basis of brain function and dysfunction and designing effective therapeutics require high resolution targeted stimulation and recording of neural activity. Optical methods have been recently developed for neural stimulation as well as functional and structural imaging. These methods call for implantable devices to deliver light into the neural tissue at depth with high spatiotemporal resolution. To address this need, rigid and flexible neurophotonic implants have been recently designed. This article reviews the state-of-the-art flexible passive and active penetrating optical neural probes developed for light delivery with minimal damage to the tissue. Passive and active flexible neurophotonic implants are compared and insights about future directions are provided.

Hollow core optical fibres have many unique properties, especially compared to traditional glass-core optical fibres [1]. Firstly, the light path is accessible and light can thus interact with the gas inside over long lengths, making them interesting for applications in gas sensing or for nonlinear processes in gasses. Hollow core fibres can also operate at wavelengths, where silica glass has poor transmission and their chromatic dispersion is not compromised by the chromatic dispersion of bulk glass. Yet another unique feature is weak interaction of light with the guiding medium (typically air), significantly increasing the damage threshold and thus making them a good candidate for high-power (average or peak power) light delivery. Another group of unique features is related to how their properties (little) change with temperature. In the presentation, we will firstly show where the common fibre optics wisdom (gained from work with standard optical fibres) tends to fail. In the second part, we will discuss how differently hollow core fibre change with temperature as compared to standard optical fibres and how it can be used for various applications, including fibre interferometry and time-stable signal transmission.

Objective:To evaluate the use of colorimetric indicators for monitoring ultraviolet-C (UV-C) light delivery to sites in patient rooms.Methods:In laboratory testing, we examined the correlation between changes in color of 2 commercial colorimetric indicators and log10 reductions in methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile spores with exposure to increasing doses of UV-C from a low-pressure mercury room decontamination device. In patient rooms, 1 of the colorimetric indicators was used to assess UV-C dose delivery to 27 sites in the room.Results:In laboratory testing, the manufacturer’s reference colors for MRSA and C. difficile reduction corresponded with doses of ∼10,000 and 46,000 µJ/cm2; these doses resulted in >3 log10 reductions in MRSA and C. difficile spores, respectively. In patient rooms, the colorimetric indicators demonstrated suboptimal delivery of UV-C dosing to shadowed areas, which was improved by providing cycles on each side of the patient bed rather than in a single position and altering device placement. Increasing duration of exposure increased the number of sites achieving adequate dosing to kill C. difficile spores.Conclusions:Commercial colorimetric indicators provide rapid and easy-to-interpret information on the UV-C dose delivered to sites in patient rooms. The indicators may be useful for training environmental services personnel and optimizing the effectiveness of UV-C room decontamination devices.

This study analyzes the light emission pattern of tapered optical fibers (TFs) across different numerical apertures (NA), core diameters, laser input powers, cone angles, and light injection angles. The results will be used to tailor optical fibers for optimal light delivery to photosensitive neuronal actuators in the non-human primate (NHP) brain.

In this paper, we report a high-frequency photoacoustic sensing (PAS) probe design consisting of an optical fiber for light delivery and two silicon acoustic delay lines (SADLs) for detecting/relaying the PA signals. A beveled tip is formed at the distal end of the optical fiber to overlap the illumination region with the detection zone of the SADLs. Detected PA signals are transmitted through the SADLs with low loss at frequencies up to 17 MHz. For demonstration, a prototype PAS probe using SADLs is designed, fabricated, and tested. Testing results show that the PAS probe provides superior sensitivity with considerable high-frequency improvement.

We present a novel Brillouin fibre probe to achieve background-free remote mapping of micromechanical properties in tissue-mimicking hydrogel-water phantom. This Brillouin imaging system is designed using a low loss hollow core optical fibre and miniature objective for efficient light delivery and scattered light collection. The system efficiency and focusing power is comparable to free space Brillouin optical systems. This demonstration paves the way towards a wide range of biomedical and bioengineering applications where non-contact, label-free and damage-free mechanical imaging is required to retrieve in situ and in vivo microscopic viscoelastic properties of tissues and biomaterials.

The purpose of this study was to determine if therapeutic efficacy of a Cetuximab based near-infrared (NIR) targeted photo therapy (TPT) was dependent on light delivery strategies. We examined the cytotoxic effects of TPT in a pancreatic cancer mouse model, when administered to tumors interstitially and superficially.A subcutaneous mouse model of pancreatic cancer using BXPC-3 -GFP cells was established in male athymic (nu/nu) mice. The mice received intravenous (IV) injection of Cetuximab-IR700DX, 24 hours prior to near-infrared light irradiation. Interstitial illumination was administered at a 400mW/cm fixed power output, at a light dose of 100 J/cm to half the mice and at 300 J/cm to the remaining mice. Superficial illumination was administered at a 150mw/cm2 fixed power density at a dose of 50 J/cm2 to half the mice, and at 250 J/cm2 to the other half. Cellular damage and decrease in cell viability was determined by the decrease in GFP fluorescence intensity levels in whole animal images and in relative intensity measurements.Interstitially administered TPT resulted in greater long-term permanent damage (72 hours post treatment) to tumor cells (0% recovery at low dose, and 11% recovery at high dose) compared to superficially administered TPT (1% recovery at low dose, and 44% recovery at high dose). While these results demonstrated that near-infrared targeted photo therapy efficacy was dependent on the type of light delivery strategy, overall, both superficial and interstitial Cet-IR700DX based near-infrared targeted photo therapy can effect significant long-term damage (less signal recovery) to pancreatic cancer cells in vivo at lower doses regimens, compared to higher dose regimens (higher signal recovery).

Sensory systems that efficiently transduce physical energy into neural signaling are advantageous for survival. The vertebrate retina poses a challenge to such efficiency, featuring an inverted structure with multiple neural layers through which photons must pass, risking premature absorption or scattering. Moreover, mammalian photoceptors aggregate an unusual amount of mitochondria in the ellipsoid region immediately before the light-sensitive outer segments (OS). While these mitochondria are required to support the high metabolic demands of phototransduction, it is yet unknown their impact on light transmission. Here we demonstrate via direct live-imaging and computational modeling that such tightly packed mitochondria concentrate light to enter the OS for detection. Intriguingly, this “microlens”-like feature of cone mitochondria delivers light with an angular dependence akin to the Stiles-Crawford effect, an essential visual phenomenon that improves resolution. We thus establish an unconventional optical function for cone mitochondria, energy-producing organelles, providing insight into their role in the interpretation of noninvasive optical tools for vision research and ophthalmology clinics.

The challenges of feeding an increasing population, an increasingly urban population and within an increasingly challenging global environment have focused ideas on new ways to grow food. Growing food in a controlled environment (CE) is not new but new technologies such as broad-spectrum LEDs and robotics are generating new opportunities. Growth recipes can be tailored to plant species in a CE and plasticity in plant responses to the environment may be utilized to make growth systems more efficient for improved yield and crop quality. Light use efficiency within CE must consider energy requirements, yield and impacts on quality. We hypothesized that understanding how plants change their morphology and physiology in response to light will allow us to identify routes to make light more efficient for delivery of high-quality produce. We focused on responses to light in Lollo rosso lettuce which produces compact, crinkly and highly pigmented leaves. We compared the spectra of the commonly used artificial light sources in indoor farming (compact fluorescence tubes, FL, and broad-spectrum light-emitting diodes, LEDs) at two irradiance levels (270 and 570 μmol m–2s–1). We discovered LEDs (λP: 451, 634, and 665 nm) produced the same amount of produce for half the incident energy of FL (T5). At higher irradiances LEDs produced 9% thicker leaves, 13% larger rosettes and 15% greater carotenoid content. Leaves differed in light absorptance with plants grown under lower FL absorbing 30% less of mid-range wavelengths. We show that the relative efficiencies of LED and FL is a function of the irradiances compared and demonstrate the importance of understanding the asymptotes of yield and quality traits. Increasing our understanding of structural and biochemical changes that occur under different combination of wavelengths may allow us to better optimize light delivery, select for different ranges of plasticity in crop plants and further optimize light recipes.

We have recently demonstrated flexible Parylene photonic waveguides with embedded micromirrors. Here, the out-of-plane beam profile of the micromirrors is characterized using a combination of simulation and experiments.

Although multiphoton microscopy enables optical control and monitoring of neural activity with single cells resolution over a depth of several hundreds of micrometers, the scattering nature of the brain tissue requires implantable optical neural interfaces to access subcortical structures. If micro light-emitting devices (μLEDs) and solid-state waveguides represent important technological advancements for the field, multimodal optical fibers (MMFs) are still the most diffused tool in neuroscience labs to interface with deep regions of the brain. At a first glance, MMFs can be seen as very limited systems. However, new studies and discoveries in optics, photonics, and technological solutions for their application to neuroscience research have enabled applications of MMF where competing technologies fail. In this framework, the chapter starts with a description of optical neural interfaces based on MMF, with specific reference on recent works analyzing the performances of this approach to deliver and collect light from scattering tissue. The discussion then focuses on how peculiar features of MMFs can be exploited to obtain unconventional applications, including brain imaging through a single multimode fiber, multifunctional neural interfaces, and depth-resolved light delivery and functional fluorescence collection.

The use of micro-needle for advanced self-administration and cutaneous therapy still represent a desired solution that could open towards still unexplored medical market. Recently we have developed a fabrication method that avoids one of the major drawbacks of conventional processes by using a mold-less direct fabrication approach based on electro-drawing of microneedle from sessile drops of biodegradable polymer. The method is completely contact-free, simple and low-cost. On the other side, the intriguing future developments of biodegradable microneedles is the possibility to functionalize and use the microneedles for phototherapy, and/or light assisting for in-situ drug activation or other functionalization that could require light delivery. Here we show that it is possible to fabricate microneedles able to focus and transmit light. In particular, we report how an electro-drawn microneedle, realized by a single-step process, can be used as a sort of light guiding micro-photonic element at the aim to delivery light form its tip. We demonstrate the light guiding properties of these conical structures showing preliminary modelling results combined with the experimental optical characterization. We believe that the proposed approach could be further exploited and could inspire future fabrication of smart nanobiophotonic devices combing multiple functionalities for implantable medicine and drug-delivery applications. © 1995-2012 IEEE.