Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain?

Tailoring photobiomodulation to enhance tissue regeneration

Photobiomodulation (PBM), the use of biocompatible tissue-penetrating light to interact with intracellular chromophores to modulate the fates of cells and tissues, has emerged as a promising non-invasive approach to enhancing tissue regeneration. Unlike photodynamic or photothermal therapies that require the use of photothermal agents or photosensitizers, PBM treatment does not need external agents. With its non-harmful nature, PBM has demonstrated efficacy in enhancing molecular secretions and cellular functions relevant to tissue regeneration. The utilization of low-level light from various sources in PBM targets cytochrome c oxidase, leading to increased synthesis of adenosine triphosphate, induction of growth factor secretion, activation of signaling pathways, and promotion of direct or indirect gene expression. When integrated with stem cell populations, bioactive molecules or nanoparticles, or biomaterial scaffolds, PBM proves effective in significantly improving tissue regeneration. This review consolidates findings from in vitro, in vivo, and human clinical outcomes of both PBM alone and PBM-combined therapies in tissue regeneration applications. It encompasses the background of PBM invention, optimization of PBM parameters (such as wavelength, irradiation, and exposure time), and understanding of the mechanisms for PBM to enhance tissue regeneration. The comprehensive exploration concludes with insights into future directions and perspectives for the tissue regeneration applications of PBM.

Tailoring the pore structure of iron oxide core@stellate mesoporous silica shell nanocomposites: effects on MRI and magnetic hyperthermia properties and applicability to anti-cancer therapies

Core-shell nanocomposites made of iron oxide core (IO NPs) coated with mesoporous silica (MS) shells are promising theranostic agents. While the core is being used as an efficient heating nanoagent under alternating magnetic field (AMF) and near infra-red (NIR) light and as a suitable contrast agent for magnetic resonance imaging (MRI), the MS shell is particularly relevant to ensure colloidal stability in a biological buffer and to transport a variety of therapeutics. However, a major challenge with such inorganic nanostructures is the design of adjustable silica structures, especially with tunable large pores which would be useful, for instance, for the delivery of large therapeutic biomolecule loading and further sustained release. Furthermore, the effect of tailoring a porous silica structure on the magneto- or photothermal dissipation still remains poorly investigated. In this work, we undertake an in-depth investigation of the growth of stellate mesoporous silica (STMS) shells around IO NPs cores and of their micro/mesoporous features respectively through time-lapse and in situ liquid phase transmission electron microscopy (LPTEM) and detailed nitrogen isotherm adsorption studies. We found here that the STMS shell features (thickness, pore size, surface area) can be finely tuned by simply controlling the sol-gel reaction time, affording a novel range of IO@STMS core@shell NPs. Finally, regarding the responses under alternating magnetic fields and NIR light which are evaluated as a function of the silica structure, IO@STMS NPs having a tunable silica shell structure are shown to be efficient as T2-weighted MRI agents and as heating agents for magneto- and photoinduced hyperthermia. Furthermore, such IO@STMS are found to display anti-cancer effects in pancreatic cancer cells under magnetic fields (both alternating and rotating).

Photobiomodulation Therapy on Brain: Pioneering an Innovative Approach to Revolutionize Cognitive Dynamics

Photobiomodulation (PBM) therapy on the brain employs red to near-infrared (NIR) light to treat various neurological and psychological disorders. The mechanism involves the activation of cytochrome c oxidase in the mitochondrial respiratory chain, thereby enhancing ATP synthesis. Additionally, light absorption by ion channels triggers the release of calcium ions, instigating the activation of transcription factors and subsequent gene expression. This cascade of events not only augments neuronal metabolic capacity but also orchestrates anti-oxidant, anti-inflammatory, and anti-apoptotic responses, fostering neurogenesis and synaptogenesis. It shows promise for treating conditions like dementia, stroke, brain trauma, Parkinson's disease, and depression, even enhancing cognitive functions in healthy individuals and eliciting growing interest within the medical community. However, delivering sufficient light to the brain through transcranial approaches poses a significant challenge due to its limited penetration into tissue, prompting an exploration of alternative delivery methods such as intracranial and intranasal approaches. This comprehensive review aims to explore the mechanisms through which PBM exerts its effects on the brain and provide a summary of notable preclinical investigations and clinical trials conducted on various brain disorders, highlighting PBM's potential as a therapeutic modality capable of effectively impeding disease progression within the organism-a task often elusive with conventional pharmacological interventions.

Enhancing Targeted Drug Delivery through Cell-Specific Endosomal Escape

Endosome is a major barrier in the intracellular delivery of drugs, especially for biologics, such as proteins, peptides, and nucleic acids. After being endocytosed, these cargos will be trapped inside the endosomal compartments and finally degraded in the lysosomes. Thus, various strategies have been developed to facilitate the escape of cargos from the endosomes to improve the intracellular delivery efficiency. While the majority of the studies are focusing on strengthening the endosomal escape capability to maximize the delivery outcome, recent evidence suggests that a careful control of the endosomal escape process could provide opportunity for targeted drug delivery. In this concept review, we examined current delivery systems that can sense intra-endosomal factors or external stimuli for controlling endosomal escape toward a targeted intracellular delivery of cargos. Furthermore, the prospects and challenges of such strategies are discussed.

Targeted Liposomal Drug Delivery: Overview of the Current Applications and Challenges

In drug development, it is not uncommon that an active substance exhibits efficacy in vitro but lacks the ability to specifically reach its target in vivo. As a result, targeted drug delivery has become a primary focus in the pharmaceutical sciences. Since the approval of Doxil® in 1995, liposomes have emerged as a leading nanoparticle in targeted drug delivery. Their low immunogenicity, high versatility, and well-documented efficacy have led to their clinical use against a wide variety of diseases. That being said, every disease is accompanied by a unique set of physiological conditions, and each liposomal product must be formulated with this consideration. There are a multitude of different targeting techniques for liposomes that can be employed depending on the application. Passive techniques such as PEGylation or the enhanced permeation and retention effect can improve general pharmacokinetics, while active techniques such as conjugating targeting molecules to the liposome surface may bring even further specificity. This review aims to summarize the current strategies for targeted liposomes in the treatment of diseases.

Photobiomodulation in experimental models of Alzheimer's disease: state-of-the-art and translational perspectives

Alzheimer's disease (AD) poses a significant public health problem, affecting millions of people across the world. Despite decades of research into therapeutic strategies for AD, effective prevention or treatment for this devastating disorder remains elusive. In this review, we discuss the potential of photobiomodulation (PBM) for preventing and alleviating AD-associated pathologies, with a focus on the biological mechanisms underlying this therapy. Future research directions and guidance for clinical practice for this non-invasive and non-pharmacological therapy are also highlighted. The available evidence indicates that different treatment paradigms, including transcranial and systemic PBM, along with the recently proposed remote PBM, all could be promising for AD. PBM exerts diverse biological effects, such as enhancing mitochondrial function, mitigating the neuroinflammation caused by activated glial cells, increasing cerebral perfusion, improving glymphatic drainage, regulating the gut microbiome, boosting myokine production, and modulating the immune system. We suggest that PBM may serve as a powerful therapeutic intervention for AD.

Directed physiological networks in the human prefrontal cortex at rest and post transcranial photobiomodulation

Cerebral infra-slow oscillation (ISO) is a source of vasomotion in endogenic (E; 0.005-0.02 Hz), neurogenic (N; 0.02-0.04 Hz), and myogenic (M; 0.04-0.2 Hz) frequency bands. In this study, we quantified changes in prefrontal concentrations of oxygenated hemoglobin (Δ[HbO]) and redox-state cytochrome c oxidase (Δ[CCO]) as hemodynamic and metabolic activity metrics, and electroencephalogram (EEG) powers as electrophysiological activity, using concurrent measurements of 2-channel broadband near-infrared spectroscopy and EEG on the forehead of 22 healthy participants at rest. After preprocessing, the multi-modality signals were analyzed using generalized partial directed coherence to construct unilateral neurophysiological networks among the three neurophysiological metrics (with simplified symbols of HbO, CCO, and EEG) in each E/N/M frequency band. The links in these networks represent neurovascular, neurometabolic, and metabolicvascular coupling (NVC, NMC, and MVC). The results illustrate that the demand for oxygen by neuronal activity and metabolism (EEG and CCO) drives the hemodynamic supply (HbO) in all E/N/M bands in the resting prefrontal cortex. Furthermore, to investigate the effect of transcranial photobiomodulation (tPBM), we performed a sham-controlled study by delivering an 800-nm laser beam to the left and right prefrontal cortex of the same participants. After performing the same data processing and statistical analysis, we obtained novel and important findings: tPBM delivered on either side of the prefrontal cortex triggered the alteration or reversal of directed network couplings among the three neurophysiological entities (i.e., HbO, CCO, and EEG frequency-specific powers) in the physiological network in the E and N bands, demonstrating that during the post-tPBM period, both metabolism and hemodynamic supply drive electrophysiological activity in directed network coupling of the prefrontal cortex (PFC). Overall, this study revealed that tPBM facilitates significant modulation of the directionality of neurophysiological networks in electrophysiological, metabolic, and hemodynamic activities.

Vein segmentation and visualization of upper and lower extremities using convolution neural network

OBJECTIVES

The study focused on developing a reliable real-time venous localization, identification, and visualization framework based upon deep learning (DL) self-parametrized Convolution Neural Network (CNN) algorithm for segmentation of the venous map for both lower and upper limb dataset acquired under unconstrained conditions using near-infrared (NIR) imaging setup, specifically to assist vascular surgeons during venipuncture, vascular surgeries, or Chronic Venous Disease (CVD) treatments.

METHODS

A portable image acquisition setup has been designed to collect venous data (upper and lower extremities) from 72 subjects. A manually annotated image dataset was used to train and compare the performance of existing well-known CNN-based architectures such as ResNet and VGGNet with self-parameterized U-Net, improving automated vein segmentation and visualization.

RESULTS

Experimental results indicated that self-parameterized U-Net performs better at segmenting the unconstrained dataset in comparison with conventional CNN feature-based learning models, with a Dice score of 0.58 and displaying 96.7 % accuracy for real-time vein visualization, making it appropriate to locate veins in real-time under unconstrained conditions.

CONCLUSIONS

Self-parameterized U-Net for vein segmentation and visualization has the potential to reduce risks associated with traditional venipuncture or CVD treatments by outperforming conventional CNN architectures, providing vascular assistance, and improving patient care and treatment outcomes.

Disentangling the effects of near-infrared light stimulation and exercise on cognitive function in fNIRS studies

Functional near-infrared spectroscopy (fNIRS) studies often aim to measure changes in the brain's hemodynamic response in relation to a specific intervention. We recently showed how a fNIRS device could induce photobiomodulatory effects on cognition by using its near-infrared (NIR) light. However, so far, fNIRS research has overlooked the stimulatory potential intrinsic to this technique. The work by Kuwamizu et al. (2023) on pupil dynamics during exercise is no exception. Here, we suggest a fix to their experimental design, which could be taken into account in other fNIRS studies, to guarantee an adequate level of control for possible unconsidered photobiomodulatory effects.

Devices used for photobiomodulation of the brain-a comprehensive and systematic review

A systematic review was conducted to determine the trends in devices and parameters used for brain photobiomodulation (PBM). The revised studies included clinical and cadaveric approaches, in which light stimuli were applied to the head and/or neck. PubMed, Scopus, Web of Science and Google Scholar databases were used for the systematic search. A total of 2133 records were screened, from which 97 were included in this review. The parameters that were extracted and analysed in each article were the device design, actuation area, actuation site, wavelength, mode of operation, power density, energy density, power output, energy per session and treatment time. To organize device information, 11 categories of devices were defined, according to their characteristics. The most used category of devices was laser handpieces, which relate to 21% of all devices, while 28% of the devices were not described. Studies for cognitive function and physiological characterisation are the most well defined ones and with more tangible results. There is a lack of consistency when reporting PBM studies, with several articles under defining the stimulation protocol, and a wide variety of parameters used for the same health conditions (e.g., Alzheimer's or Parkinson's disease) resulting in positive outcomes. Standardization for the report of these studies is warranted, as well as sham-controlled comparative studies to determine which parameters have the greatest effect on PBM treatments for different neurological conditions.

4D Printed Protein-AuNR Nanocomposites with Photothermal Shape Recovery

4D printing is the 3D printing of objects that change chemically or physically in response to an external stimulus over time. Photothermally responsive shape memory materials are attractive for their ability to undergo remote activation. While photothermal methods using gold nanorods (AuNRs) have been used for shape recovery, 3D patterning of these materials into objects with complex geometries using degradable materials has not been addressed. Here, we report on the fabrication of 3D printed shape memory bioplastics with photo-activated shape recovery. Protein-based nanocomposites based on bovine serum albumin (BSA), poly (ethylene glycol) diacrylate and gold nanorods were developed for vat photopolymerization. These 3D printed bioplastics were mechanically deformed under high loads, and the proteins served as mechanoactive elements that unfolded in an energy-dissipating mechanism that prevented fracture of the thermoset. The bioplastic object maintained its metastable shape-programmed state under ambient conditions. Subsequently, up to 99% shape recovery was achieved within 1 min of irradiation with near-infrared light. Mechanical characterization and small angle X-ray scattering (SAXS) analysis suggest that the proteins mechanically unfold during the shape programming step and may refold during shape recovery. These composites are promising materials for the fabrication of biodegradable shape-morphing devices for robotics and medicine.

Near-infrared photoimmunotherapy targeting Nectin-4 in a preclinical model of bladder cancer

Enfortumab vedotin (EV), an antibody-drug conjugate (ADC) that targets Nectin-4, has shown promising results in the treatment of bladder cancer. However, multiple resistance mechanisms that are unique to ADCs limit the therapeutic potential of EV in clinical practice. Here, we developed and tested a Nectin-4-targeted near-infrared photoimmunotherapy (NIR-PIT) that utilizes the same target as EV but utilizes a distinct cytotoxic and immunotherapeutic pathway in preclinical models of bladder cancer. NIR-PIT was effective in vitro against luminal subtype human bladder cancer cell lines (RT4, RT112, MGH-U3, SW780, and HT1376-luc), but not against other subtype cell lines (UMUC3 and T24). In vivo, the tumor site was clearly visible by Nectin-4-IR700 fluorescence 24 h after its administration, suggesting the potential as an intraoperative imaging modality. NIR-PIT significantly suppressed tumor growth and prolonged survival in SW780 and RT112 xenograft models. Weekly treatment with NIR-PIT further improved tumor control in RT112 xenograft models. The effectiveness of NIR-PIT was also confirmed in HT1376-luc orthotopic xenograft models. Histological analysis verified that NIR-PIT induced a significant pathologic response. Taken together, Nectin-4-targeted NIR-PIT shows promise as a treatment for luminal subtype bladder cancers.

From functional neuroimaging to neurostimulation: fNIRS devices as cognitive enhancers

Functional near-infrared spectroscopy (fNIRS) relies on near-infrared (NIR) light for changes in tissue oxygenation. For decades, this technique has been used in neuroscience to measure cortical activity. However, recent research suggests that NIR light directed to neural populations can modulate their activity through "photobiomodulation" (PBM). Yet, fNIRS is being used exclusively as a measurement tool. By adopting cognitive tests sensitive to prefrontal functioning, we show that a 'classical' fNIRS device, placed in correspondence of the prefrontal cortices of healthy participants, induces faster RTs and better accuracy in some of the indexes considered. A well-matched control group, wearing the same but inactive device, did not show any improvement. Hence, our findings indicate that the 'standard' use of fNIRS devices generates PBM impacting cognition. The neuromodulatory power intrinsic in that technique has been so far completely overlooked, and future studies will need to take this into account.

Glioblastoma Therapy: Past, Present and Future

Glioblastoma (GB) stands out as the most prevalent and lethal form of brain cancer. Although great efforts have been made by clinicians and researchers, no significant improvement in survival has been achieved since the Stupp protocol became the standard of care (SOC) in 2005. Despite multimodality treatments, recurrence is almost universal with survival rates under 2 years after diagnosis. Here, we discuss the recent progress in our understanding of GB pathophysiology, in particular, the importance of glioma stem cells (GSCs), the tumor microenvironment conditions, and epigenetic mechanisms involved in GB growth, aggressiveness and recurrence. The discussion on therapeutic strategies first covers the SOC treatment and targeted therapies that have been shown to interfere with different signaling pathways (pRB/CDK4/RB1/P16ink4, TP53/MDM2/P14arf, PI3k/Akt-PTEN, RAS/RAF/MEK, PARP) involved in GB tumorigenesis, pathophysiology, and treatment resistance acquisition. Below, we analyze several immunotherapeutic approaches (i.e., checkpoint inhibitors, vaccines, CAR-modified NK or T cells, oncolytic virotherapy) that have been used in an attempt to enhance the immune response against GB, and thereby avoid recidivism or increase survival of GB patients. Finally, we present treatment attempts made using nanotherapies (nanometric structures having active anti-GB agents such as antibodies, chemotherapeutic/anti-angiogenic drugs or sensitizers, radionuclides, and molecules that target GB cellular receptors or open the blood-brain barrier) and non-ionizing energies (laser interstitial thermal therapy, high/low intensity focused ultrasounds, photodynamic/sonodynamic therapies and electroporation). The aim of this review is to discuss the advances and limitations of the current therapies and to present novel approaches that are under development or following clinical trials.

Phototherapy for age-related brain diseases: Challenges, successes and future

Brain diseases present a significant obstacle to both global health and economic progress, owing to their elusive pathogenesis and the limited effectiveness of pharmaceutical interventions. Phototherapy has emerged as a promising non-invasive therapeutic modality for addressing age-related brain disorders, including stroke, Alzheimer's disease (AD), and Parkinson's disease (PD), among others. This review examines the recent progressions in phototherapeutic interventions. Firstly, the article elucidates the various wavelengths of visible light that possess the capability to penetrate the skin and skull, as well as the pathways of light stimulation, encompassing the eyes, skin, veins, and skull. Secondly, it deliberates on the molecular mechanisms of visible light on photosensitive proteins, within the context of brain disorders and other molecular pathways of light modulation. Lastly, the practical application of phototherapy in diverse clinical neurological disorders is indicated. Additionally, this review presents novel approaches that combine phototherapy and pharmacological interventions. Moreover, it outlines the limitations of phototherapeutics and proposes innovative strategies to improve the treatment of cerebral disorders.

Photobiomodulation for Neurodegenerative Diseases: A Scoping Review

Neurodegenerative diseases involve the progressive dysfunction and loss of neurons in the central nervous system and thus present a significant challenge due to the absence of effective therapies for halting or reversing their progression. Based on the characteristics of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD), which have prolonged incubation periods and protracted courses, exploring non-invasive physical therapy methods is essential for alleviating such diseases and ensuring that patients have an improved quality of life. Photobiomodulation (PBM) uses red and infrared light for therapeutic benefits and functions by stimulating, healing, regenerating, and protecting organizations at risk of injury, degradation, or death. Over the last two decades, PBM has gained widespread recognition as a non-invasive physical therapy method, showing efficacy in pain relief, anti-inflammatory responses, and tissue regeneration. Its application has expanded into the fields of neurology and psychiatry, where extensive research has been conducted. This paper presents a review and evaluation of studies investigating PBM in neurodegenerative diseases, with a specific emphasis on recent applications in AD and PD treatment for both animal and human subjects. Molecular mechanisms related to neuron damage and cognitive impairment are scrutinized, offering valuable insights into PBM's potential as a non-invasive therapeutic strategy.

Near-Infrared Triggered Degradation for Transient Electronics

Electronics that disintegrate after stable operation present exciting opportunities for niche medical implant and consumer electronics applications. The disintegration of these devices can be initiated due to their medium conditions or triggered by external stimuli, which enables on-demand transition. An external stimulation method that can penetrate deep inside the body could revolutionize the use of transient electronics as implantable medical devices (IMDs), eliminating the need for secondary surgery to remove the IMDs. We report near-infrared (NIR) light-triggered transition of metastable cyclic poly(phthalaldehyde) (cPPA) polymers. The transition of the encapsulation layer is achieved through the conversion of NIR light to heat, facilitated by bioresorbable metals, such as molybdenum (Mo). We reported a rapid degradation of cPPA encapsulation layer about 1 min, and the rate of degradation can be controlled by laser power and exposure time. This study offers a new approach for light triggerable transient electronics for IMDs due to the deep penetration depth of NIR light through to organs and tissues.

In vivo attenuation profile of 660 nm and 830 nm wavelengths on human elbow skin and calcaneus tendon of different phototypes

Physical factors and tissue characteristics determine the transmission of light through tissues. One of the significant clinical limitations of photobiomodulation is the quantification of fluence delivered at application sites and optical penetration depth in vivo. There is also the difficulty of determining the distances of the application points to cover a uniformly irradiated area. Thus, the aim was to evaluate in vivo the influence of melanin on light transmission of the 660 nm and 830 nm laser wavelengths on skin and tendon. Thirty young individuals of both sexes were recruited, divided into two groups based on melanin index, and submitted to photobiomodulation protocols in the posterior region of the elbow (skin-skin) and the calcaneus tendon (skin-tendon-skin). The irradiation area was evaluated using a homemade linear array of five sensors. We found significant transmission power values for different melanin indexes and wavelengths (p<0.0001). Also, different equipment can generate significant differences in the transmitted power at an 830-nm wavelength. Average scattering values are 14 mm and 21 mm for 660 nm, in higher and lower melanin index, respectively. For 830 nm, values of 20 mm and 26 mm are indicated. Laser light transmission in vivo tissues is related to wavelength, beam diameter, tissue thickness, and composition, as well as melanin index. The 830-nm laser presents higher light transmission on the skin than 660 nm. The distances between the application points can be different, with higher values for 830 nm than 660 nm.

Functionalized Nanomaterials for Inhibiting ATP-Dependent Heat Shock Proteins in Cancer Photothermal/Photodynamic Therapy and Combination Therapy

Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) and photodynamic therapy (PDT). However, PTT is limited by the self-protective nature of cells, with upregulated production of heat shock proteins (HSP) under mild hyperthermia, which also influences PDT. To reduce HSP production in cancer cells and to enhance PTT/PDT, small HSP inhibitors that can competitively bind at the ATP-binding site of an HSP could be employed. Alternatively, reducing intracellular glucose concentration can also decrease ATP production from the metabolic pathways and downregulate HSP production from glucose deprivation. Other than reversing the thermal resistance of cancer cells for mild-temperature PTT, an HSP inhibitor can also be integrated into functionalized nanomaterials to alleviate tumor hypoxia and enhance the efficacy of PDT. Furthermore, the co-delivery of a small-molecule drug for direct HSP inhibition and a chemotherapeutic drug can integrate enhanced PTT/PDT with chemotherapy (CT). On the other hand, delivering a glucose-deprivation agent like glucose oxidase (GOx) can indirectly inhibit HSP and boost the efficacy of PTT/PDT while combining these therapies with cancer starvation therapy (ST). In this review, we intend to discuss different nanomaterial-based approaches that can inhibit HSP production via ATP regulation and their uses in PTT/PDT and cancer combination therapy such as CT and ST.

Recent advances in light energy biotherapeutic strategies with photobiomodulation on central nervous system disorders

Transcranial photobiomodulation refers to irradiation of the brain through the skull using low-intensity red or near-infrared light, which is the most commonly studied method of light energy biotherapy for central nervous system disorders. The absorption of photons by specific chromophores within the cell elevates ATP synthesis, reduces oxidative stress damage, alleviates inflammation or mediates the activation of transcription factors and signaling mediators through secondary mediators, which in turn trigger downstream signaling pathways to cause a series of photobiological effects including upregulation of neurotrophic factors. Multiple mechanisms are simultaneously involved in the pathological process of central nervous system disorders. The pleiotropic treatment of transcranial photobiomodulation towards multiple targets plays a beneficial role in improving hemodynamics, neural repair and improving behaviors in central nervous system disorders such as ischemic stroke, traumatic brain injury, neurodegenerative diseases, epilepsy and depression. This review mainly introduces the mechanism and recent preclinical and clinical advances of transcranial photobiomodulation for central nervous system disorders, which will provide a reference for clinicians to understand and engage in related studies, and calls for more and larger studies to validate and develop a wider application of transcranial photobiomodulation in central nervous system.

Brain photobiomodulation therapy on neurological and psychological diseases

Photobiomodulation (PBM) therapy is an innovative treatment for neurological and psychological conditions. Complex IV of the mitochondrial respiratory chain can be stimulated by red light, which increases ATP synthesis. In addition, the ion channels' light absorption causes the release of Ca2+, which activates transcription factors and changes gene expression. Neuronal metabolism is improved by brain PBM therapy, which also promotes synaptogenesis and neurogenesis as well as anti-inflammatory. Its depression-treating potential is attracting attention for other conditions, including Parkinson's disease and dementia. Giving enough dosage for optimum stimulation using the transcranial PBM technique is challenging because of the rapidly increasing attenuation of light transmission in tissue. Different strategies like intranasal and intracranial light delivery systems have been proposed to overcome this restriction. The most recent preclinical and clinical data on the effectiveness of brain PBM therapy are studied in this review article.

Advent in proteins, nucleic acids, and biological cell membranes functionalized nanocarriers to accomplish active or homologous tumor targeting for smart amalgamated chemotherapy/photo-therapy: A review

Conventional cancer mono-therapeutic approaches including radiotherapy, surgery, and chemotherapy don't always achieve satisfactory outcomes and are frequently associated with significant limitations. Although chemotherapy is a vital intervention, its effectiveness is frequently inadequate and is associated with metastasis, multidrug resistance, off-target effect, and normal cells toxicity. Phototherapies are employed in cancer therapy, encompassing photo-dynamic and photo-thermal therapies which under favorable NIR laser light irradiation initiate the included photosensitizers and photo-thermal agents to generate ROS or thermal heat respectively for cancer cells destruction. Photo-therapy is considered noninvasive, posing no resistance, but it still suffers from several pitfalls like low penetration depth and excessive heat generation affecting neighboring tissues. Improved selectivity and tumor-homing capacity could be attained through surface modulation of nanoparticles with targeting ligands that bind to receptors, which are exclusively overexpressed on cancerous cells. Developing novel modified targeted nanoparticulate platforms integrating different therapeutic modalities like photo-therapy and chemotherapy is a topic of active research. This review aimed to highlight recent advances in proteins, nucleic acids, and biological cell membranes functionalized nanocarriers for smart combinatorial chemotherapy/photo-therapy. Nanocarriers decorated with precise targeting ligands, like aptamers, antibody, and lactoferrin, to achieve active tumor-targeting or camouflaging using various biological cell membrane coating are designed to achieve homologous tumor-targeting.

Revisiting Transcranial Light Stimulation as a Stroke Therapeutic-Hurdles and Opportunities

Near-infrared laser therapy, a special form of transcranial light therapy, has been tested as an acute stroke therapy in three large clinical trials. While the NEST trials failed to show the efficacy of light therapy in human stroke patients, there are many lingering questions and lessons that can be learned. In this review, we summarize the putative mechanism of light stimulation in the setting of stroke, highlight barriers, and challenges during the translational process, and evaluate light stimulation parameters, dosages and safety issues, choice of outcomes, effect size, and patient selection criteria. In the end, we propose potential future opportunities with transcranial light stimulation as a cerebroprotective or restorative tool for future stroke treatment.

Superficial vessel-based near infrared-assisted patient position recognition and real-time monitoring system (VIPS) for radiotherapy: A proof-of-concept study

BACKGROUND

The accuracy and precision of patient position in radiotherapy process have dramatic impacts on the tumor local control and therapy-related side effects, and there exist demands to explore effective positioning solutions, particularly in the era with great progress in imaging recognition and matching.

PURPOSE

Superficial vessel-based near infrared-assisted patient position recognition and real-time monitoring system (VIPS) was proposed to develop an automated, operator-independent and skin marker-free imaging system to improve patient setup and intrafractional motion monitoring.

METHODS

VIPS includes two components, the imaging module and the image alignment software. Using a simulated blood vessel model, multiple NIR sources with various wavelength and bolus (pseudo-skin) were evaluated in terms of imaging quality to determine the optimal light source and the upper limit of superficial fatty tissue thickness. Then the performance of VIPS with reference to either CBCT or laser setup system was conducted using 3D phantom and clinical cases enrolled into the registered clinical trial. The position displacement from VIPS and laser system was compared, as well as the systematic and random errors of VIPS setup procedure.

RESULTS

The NIR light source with the combined wavelengths of 760 nm + 940 nm (S760+940 nm ) provided the best performance among multiple tested light sources. The bolus (superficial fatty layer) thickness over 5 mm could dramatically compromise the NIR detection of vessels beneath. In the phantom study, the translational positional displacements according to VIPS guidance were within the submillimeter level with reference to CBCT, indicative of high setup accuracy. The clinical trial showed the prototype VIPS could effectively detect and control position displacement of patients in translational and rotational directions within an acceptable range, which was non-inferior to conventional laser/skin marker system.

CONCLUSION

This proof-of-concept study validated the feasibility and reliability of VIPS in guiding radiotherapy setup. However, limitations and technical challenges should be resolved prior to further clinical evaluation, including isocenter alignment, potential NIR image distortion and the impact of the superficial tissues on the recognition of vessels.

The effect of bone remodeling with photobiomodulation in dentistry: a review study

Photobiomodulation (PBM) has been emerging as a promising alternative therapy in dentistry. However, various parameters of PBM are used in different studies, and there is limited cumulative data on PBM for improving bone formation in clinical trials. The aim of this review was to evaluate the effectiveness of PBM in the process of bone remodeling in dentistry using randomized controlled trials. Initially, a total of 1,011 articles published from January 2008 to December 2021 were retrieved from five electronic databases (PubMed, Scopus, Cochrane Library, EMBASE, and CINAHL). After a two-step review, nine articles met the inclusion criteria. The parameter of PBM, group, treatment sessions, assessment times and outcomes of the included studies were reviewed. Eighty-nine percent of the studies revealed positive effects on bone formation between the laser group and the control group. Only one article reported that light-emitting diode did not significantly enhance osteogenesis. Additionally, the present study shows that Gallium aluminum arsenide of near infrared (NIR) laser with continuous mode is the most commonly used form of PBM. The biostimulatory effects are dependent on several parameters, with wavelength and dose being more important than others. Based on this review, it is suggested that the NIR range and an appropriate dose of PBM could be used to increase the efficiency of stimulating bone healing and remodeling. However, standardization of treatment protocols is needed to clarify therapeutic strategies in dentistry.

Indocyanine Green Fluorescence Imaging in the Surgical Management of Skin Squamous Cell Carcinoma

Introduction

Indocyanine green (ICG) fluorescence imaging has been used in the resection surgery and sentinel lymph node biopsy of many tumors. The aim of the present study is to verify the feasibility and effectiveness of ICG fluorescence imaging used for guiding the biopsy and resection of skin squamous cell carcinoma (SSCC).

Methods

Sixty patients were enrolled, including 18 patients of suspected SSCC and 42 patients of diagnosed SSCC on admission. The ICG fluorescence imaging-guided skin biopsy was performed preoperatively in the 18 cases of suspected SSCC. Fifty-three patients underwent ICG fluorescence imaging-guided radical excision.

Results

The results showed that 138 skin tissue samples in 60 patients with preoperative or intraoperative ICG fluorescence imaging-guide biopsy were collected. For a total number of 138 biopsies, 122 specimens were squamous cell carcinoma, and the accuracy rate was 88.4%, which was significantly higher than that of the group without preoperative ICG fluorescence imaging (41/62, 66.1%, P < 0.05). Fifty-three patients underwent surgery guided with ICG fluorescence imaging. Residual fluorescent signals in 24 patients were intraoperatively found and the excision was then expanded until the signals disappeared. Follow-up to November 2022, 12 patients died, of which 5 cases died from the tumor recurrence, and the others died due to advanced ages or other reasons. The recurrence rate was 9.4%, which was not significantly different from that of the group received routine radical resection (4/35, 11.4%, P > 0.05). Moreover, sentinel lymph nodes were successfully detected under ICG fluorescence imaging in the 4 patients with suspected lymph node metastases, and the location of lymph nodes can be precisely identified.

Conclusion

ICG fluorescence imaging technique can guide the pathology biopsy to improve the accuracy of pathological examination, and help to identify the boundaries of tumor tissues and sentinel lymph nodes to resect tumor radically during operation.

A modular phage vector platform for targeted photodynamic therapy of Gram-negative bacterial pathogens

Growing antibiotic resistance has encouraged the revival of phage-inspired antimicrobial approaches. On the other hand, photodynamic therapy (PDT) is considered a very promising research domain for the protection against infectious diseases. Yet, very few efforts have been made to combine the advantages of both approaches in a modular, retargetable platform. Here, we foster the M13 bacteriophage as a multifunctional scaffold, enabling the selective photodynamic killing of bacteria. We took advantage of the well-defined molecular biology of M13 to functionalize its capsid with hundreds of photo-activable Rose Bengal sensitizers and contemporarily target this light-triggerable nanobot to specific bacterial species by phage display of peptide targeting moieties fused to the minor coat protein pIII of the phage. Upon light irradiation of the specimen, the targeted killing of diverse Gram(-) pathogens occurred at subnanomolar concentrations of the phage vector. Our findings contribute to the development of antimicrobials based on targeted and triggerable phage-based nanobiotherapeutics.

Photobiomodulation therapy assisted orthodontic tooth movement: potential implications, challenges, and new perspectives

Over the past decade, dramatic progress has been made in dental research areas involving laser therapy. The photobiomodulatory effect of laser light regulates the behavior of periodontal tissues and promotes damaged tissues to heal faster. Additionally, photobiomodulation therapy (PBMT), a non-invasive treatment, when applied in orthodontics, contributes to alleviating pain and reducing inflammation induced by orthodontic forces, along with improving tissue healing processes. Moreover, PBMT is attracting more attention as a possible approach to prevent the incidence of orthodontically induced inflammatory root resorption (OIIRR) during orthodontic treatment (OT) due to its capacity to modulate inflammatory, apoptotic, and anti-antioxidant responses. However, a systematic review revealed that PBMT has only a moderate grade of evidence-based effectiveness during orthodontic tooth movement (OTM) in relation to OIIRR, casting doubt on its beneficial effects. In PBMT-assisted orthodontics, delivering sufficient energy to the tooth root to achieve optimal stimulation is challenging due to the exponential attenuation of light penetration in periodontal tissues. The penetration of light to the root surface is another crucial unknown factor. Both the penetration depth and distribution of light in periodontal tissues are unknown. Thus, advanced approaches specific to orthodontic application of PBMT need to be established to overcome these limitations. This review explores possibilities for improving the application and effectiveness of PBMT during OTM. The aim was to investigate the current evidence related to the underlying mechanisms of action of PBMT on various periodontal tissues and cells, with a special focus on immunomodulatory effects during OTM.

Gold Nanostars Obviate Limitations to Laser Interstitial Thermal Therapy (LITT) for the Treatment of Intracranial Tumors

PURPOSE

Laser interstitial thermal therapy (LITT) is an effective minimally invasive treatment option for intracranial tumors. Our group produced plasmonics-active gold nanostars (GNS) designed to preferentially accumulate within intracranial tumors and amplify the ablative capacity of LITT.

EXPERIMENTAL DESIGN

The impact of GNS on LITT coverage capacity was tested in ex vivo models using clinical LITT equipment and agarose gel-based phantoms of control and GNS-infused central "tumors." In vivo accumulation of GNS and amplification of ablation were tested in murine intracranial and extracranial tumor models followed by intravenous GNS injection, PET/CT, two-photon photoluminescence, inductively coupled plasma mass spectrometry (ICP-MS), histopathology, and laser ablation.

RESULTS

Monte Carlo simulations demonstrated the potential of GNS to accelerate and specify thermal distributions. In ex vivo cuboid tumor phantoms, the GNS-infused phantom heated 5.5× faster than the control. In a split-cylinder tumor phantom, the GNS-infused border heated 2× faster and the surrounding area was exposed to 30% lower temperatures, with margin conformation observed in a model of irregular GNS distribution. In vivo, GNS preferentially accumulated within intracranial tumors on PET/CT, two-photon photoluminescence, and ICP-MS at 24 and 72 hours and significantly expedited and increased the maximal temperature achieved in laser ablation compared with control.

CONCLUSIONS

Our results provide evidence for use of GNS to improve the efficiency and potentially safety of LITT. The in vivo data support selective accumulation within intracranial tumors and amplification of laser ablation, and the GNS-infused phantom experiments demonstrate increased rates of heating, heat contouring to tumor borders, and decreased heating of surrounding regions representing normal structures.

Photobiomodulation may enhance cognitive efficiency in older adults: a functional near-infrared spectroscopy study

Introduction

The relative oxygenated hemoglobin (HbO) measured using functional near-infrared spectroscopy (fNIRS) has been considered as an index for cognitive loading, with the more difficult the task, the higher the level. A previous study reported that young adults who received transcranial photobiomodulation (tPBM) showed a reduced HbO of a difficult task, suggesting that tPBM may enhance cognitive efficiency. The present study further investigated the effect of tPBM on cognitive efficiency in older adults.

Methods

Thirty participants received a single tPBM on the forehead for 350 s. Before and after tPBM, their HbO in the visual span task with various difficulties was measured with fNIRS.

Results

After tPBM, participants exhibited significantly lower HbO in a harder (span 7) but not an easier level (span 2) of the task, but their behavioral performance remained unchanged. In addition, factors affecting the reduction of HbO were examined, and the results showed that individuals with better memory (as measured by a 30-min delayed recall test) showed more reduction of HbO.

Discussion

The results suggest that tPBM may enhance cognitive efficiency, with individuals with better memory tend to benefit more.

Protocol Report on the Transcranial Photobiomodulation for Alzheimer's Disease (TRAP-AD) Study

BACKGROUND

Alzheimer's disease's (AD) prevalence is projected to increase as the population ages and current treatments are minimally effective. Transcranial photobiomodulation (t-PBM) with near-infrared (NIR) light penetrates into the cerebral cortex, stimulates the mitochondrial respiratory chain, and increases cerebral blood flow. Preliminary data suggests t-PBM may be efficacious in improving cognition in people with early AD and amnestic mild cognitive impairment (aMCI).

METHODS

In this randomized, double-blind, placebo-controlled study with aMCI and early AD participants, we will test the efficacy, safety, and impact on cognition of 24 sessions of t-PBM delivered over 8 weeks. Brain mechanisms of t-PBM in this population will be explored by testing whether the baseline tau burden (measured with 18F-MK6240), or changes in mitochondrial function over 8 weeks (assessed with 31P-MRSI), moderates the changes observed in cognitive functions after t-PBM therapy. We will also use changes in the fMRI Blood-Oxygenation-Level-Dependent (BOLD) signal after a single treatment to demonstrate t-PBM-dependent increases in prefrontal cortex blood flow.

CONCLUSION

This study will test whether t-PBM, a low-cost, accessible, and user-friendly intervention, has the potential to improve cognition and function in an aMCI and early AD population.

Boolean logic in synthetic biology and biomaterials: Towards living materials in mammalian cell therapeutics

BACKGROUND

The intersection of synthetic biology and biomaterials promises to enhance safety and efficacy in novel therapeutics. Both fields increasingly employ Boolean logic, which allows for specific therapeutic outputs (e.g., drug release, peptide synthesis) in response to inputs such as disease markers or bio-orthogonal stimuli. Examples include stimuli-responsive drug delivery devices and logic-gated chimeric antigen receptor (CAR) T cells. In this review, we explore recent manuscripts highlighting the potential of synthetic biology and biomaterials with Boolean logic to create novel and efficacious living therapeutics.

MAIN BODY

Collaborations in synthetic biology and biomaterials have led to significant advancements in drug delivery and cell therapy. Borrowing from synthetic biology, researchers have created Boolean-responsive biomaterials sensitive to multiple inputs including pH, light, enzymes and more to produce functional outputs such as degradation, gel-sol transition and conformational change. Biomaterials also enhance synthetic biology, particularly CAR T and adoptive T cell therapy, by modulating therapeutic immune cells in vivo. Nanoparticles and hydrogels also enable in situ generation of CAR T cells, which promises to drive down production costs and expand access to these therapies to a larger population. Biomaterials are also used to interface with logic-gated CAR T cell therapies, creating controllable cellular therapies that enhance safety and efficacy. Finally, designer cells acting as living therapeutic factories benefit from biomaterials that improve biocompatibility and stability in vivo.

CONCLUSION

By using Boolean logic in both cellular therapy and drug delivery devices, researchers have achieved better safety and efficacy outcomes. While early projects show incredible promise, coordination between these fields is ongoing and growing. We expect that these collaborations will continue to grow and realize the next generation of living biomaterial therapeutics.

Evaluation of the effectiveness of photobiomodulation therapy as an alternative method to local anesthesia injection in pediatric dentistry

Background

The idea of receiving local anesthesia (LA) via an injection is a major source of dental fear and anxiety. In children, dental anxiety is considered the main reason for avoiding dental treatments. Moreover, there are potential complications during/after LA administration. Thus, it is necessary to search for painless, low-risk, and nonpharmacological anesthetic approaches.

Aim

This study was performed to evaluate the effectiveness of photobiomodulation (PBM) therapy as an alternative method to LA injection for conventional restorative treatments in pediatric patients.

Settings and Design

This was a split-mouth randomized clinical study.

Materials and Methods

The study included 15 children between 6 and 12 years old. Each child had 2 similar contralateral caries lesions in the first permanent molars in the same jaw, total (30) teeth. For each child, one tooth was treated under conventional LA injection and the other was treated under PBM-based anesthesia. The Wong-Baker's Faces Pain Scale was used for reporting the pain and discomfort levels at the end of the treatments.

Statistical Analysis

Data statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 20. Mann-Whitney U-test was used to compare between the groups.

Results

The PBM-based anesthesia group recorded a mean pain score of 2.27 ± 1.28. The conventional LA group recorded a mean pain score of 1.73 ± 0.7. The difference between the groups was not statistically significant (P = 0.168).

Conclusions

PBM-based anesthesia may be an optional alternative to LA injection for conventional restorative treatments in children with dental anxiety, needle phobia, or special needs, and it deserves further studies and improvement.

Photodynamic Therapy for Glioblastoma: Illuminating the Path toward Clinical Applicability

Glioblastoma (GBM) is the most common adult brain cancer. Despite extensive treatment protocols comprised of maximal surgical resection and adjuvant chemo-radiation, all glioblastomas recur and are eventually fatal. Emerging as a novel investigation for GBM treatment, photodynamic therapy (PDT) is a light-based modality that offers spatially and temporally specific delivery of anti-cancer therapy with limited systemic toxicity, making it an attractive option to target GBM cells remaining beyond the margins of surgical resection. Prior PDT approaches in GBM have been predominantly based on 5-aminolevulinic acid (5-ALA), a systemically administered drug that is metabolized only in cancer cells, prompting the release of reactive oxygen species (ROS), inducing tumor cell death via apoptosis. Hence, this review sets out to provide an overview of current PDT strategies, specifically addressing both the potential and shortcomings of 5-ALA as the most implemented photosensitizer. Subsequently, the challenges that impede the clinical translation of PDT are thoroughly analyzed, considering relevant gaps in the current PDT literature, such as variable uptake of 5-ALA by tumor cells, insufficient tissue penetrance of visible light, and poor oxygen recovery in 5-ALA-based PDT. Finally, novel investigations with the potential to improve the clinical applicability of PDT are highlighted, including longitudinal PDT delivery, photoimmunotherapy, nanoparticle-linked photosensitizers, and near-infrared radiation. The review concludes with commentary on clinical trials currently furthering the field of PDT for GBM. Ultimately, through addressing barriers to clinical translation of PDT and proposing solutions, this review provides a path for optimizing PDT as a paradigm-shifting treatment for GBM.

Diagnostic and Therapeutic Approaches for Glioblastoma and Neuroblastoma Cancers Using Chlorotoxin Nanoparticles

Glioblastoma multiforme (GB) and high-risk neuroblastoma (NB) are known to have poor therapeutic outcomes. As for most cancers, chemotherapy and radiotherapy are the current mainstay treatments for GB and NB. However, the known limitations of systemic toxicity, drug resistance, poor targeted delivery, and inability to access the blood-brain barrier (BBB), make these treatments less satisfactory. Other treatment options have been investigated in many studies in the literature, especially nutraceutical and naturopathic products, most of which have also been reported to be poorly effective against these cancer types. This necessitates the development of treatment strategies with the potential to cross the BBB and specifically target cancer cells. Compounds that target the endopeptidase, matrix metalloproteinase 2 (MMP-2), have been reported to offer therapeutic insights for GB and NB since MMP-2 is known to be over-expressed in these cancers and plays significant roles in such physiological processes as angiogenesis, metastasis, and cellular invasion. Chlorotoxin (CTX) is a promising 36-amino acid peptide isolated from the venom of the deathstalker scorpion, Leiurus quinquestriatus, demonstrating high selectivity and binding affinity to a broad-spectrum of cancers, especially GB and NB through specific molecular targets, including MMP-2. The favorable characteristics of nanoparticles (NPs) such as their small sizes, large surface area for active targeting, BBB permeability, etc. make CTX-functionalized NPs (CTX-NPs) promising diagnostic and therapeutic applications for addressing the many challenges associated with these cancers. CTX-NPs may function by improving diffusion through the BBB, enabling increased localization of chemotherapeutic and genotherapeutic drugs to diseased cells specifically, enhancing imaging modalities such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), optical imaging techniques, image-guided surgery, as well as improving the sensitization of radio-resistant cells to radiotherapy treatment. This review discusses the characteristics of GB and NB cancers, related treatment challenges as well as the potential of CTX and its functionalized NP formulations as targeting systems for diagnostic, therapeutic, and theranostic purposes. It also provides insights into the potential mechanisms through which CTX crosses the BBB to bind cancer cells and provides suggestions for the development and application of novel CTX-based formulations for the diagnosis and treatment of GB and NB in the future.

Generalised analytical model of the transition power densities of the upconversion luminescence and quantum yield

The quantum yield (QY) evaluation of upconverting nanoparticles (UCNPs) is an essential step in the characterisation of such materials. The QY of UCNPs is governed by competing mechanisms of populating and depopulating the electronic energy levels involved in the upconversion (UC), namely linear decay rates and energy transfer rates. As a consequence, at low excitation, the QY excitation power density (ρ) dependence obeys the power law ρ^n-1, where n represents the number of absorbed photons required for the emission of a single upconverted photon and determines the order of the energy transfer upconversion (ETU) process. At high power densities, the QY transits to a saturation level independent of the ETU process and the number of excitation photons, as a result of an anomalous power density dependence present in UCNPs. Despite the importance of this non-linear process for several applications (e.g., living tissue imaging and super-resolution-microscopy), little has been reported in the literature regarding theoretical studies to describe the UC QY, especially for ETUs with order higher than two. Therefore, this work presents a simple general analytical model, which introduces the concept of the transition power density points and QY saturation to characterise the QY of an arbitrary ETU process. The transition power density points determine where the power density dependence of the QY and the UC luminescence changes. The results provided in this paper from fitting the model to experimental QY data of a Yb-Tm codoped β-UCNP for 804 nm and 474 nm emissions (ETU2 and ETU3 processes, respectively) exemplify the application of the model. The common transition points found for both processes were compared to each other showing strong agreement with theory, as well as, compared to previous reports when possible.

Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation

The purpose of this study was to investigate photothermal aspects of photobiomodulation therapies (PBMT) in vitro to assist in the development of safe clinical parameters with respect to higher-power devices with large surface applicators. Laser wavelengths in the range of 650 nm-1064 nm were investigated using a thermal camera. Thermographic measures of surface and sub-surface temperature variations of similar lean porcine muscle tissue samples were recorded for a series of calibrated experiments. A thermal comparison was then made between Flat-top and Gaussian beam spatial distribution devices. Outcome data were subjected to statistical analysis using an ANOVA model. Results acquired at similar parameters of irradiance indicated that the application of the 980 nm wavelength was associated with the highest rise in temperature, which decreased with other wavelengths in the order 980 > 1064 ≈ 650 >>> 810 nm (p < 5 × 10^-20). All wavelengths assessed were associated with a significant temperature increase, and with the exception of 810 nm, all exceeded the threshold of a 6 °C rise within the prescribed parameter limits. Optical scanning by movement of the applied source over a relevant area was found to offer effective mitigation of these temperature increases. An extended discussion is presented, analysing the clinical significance of the study outcomes. Recommendations are made within the limits of this in vitro study in order to assist future clinical investigations.

A Machine Learning-optimized system for on demand, pulsatile, photo- and chemo-therapeutic treatment using near-infrared responsive MoS 2 -based microparticles in a breast cancer model

Cancer therapy research is of high interest because of the persistence and mortality of the disease and the side effects of traditional therapeutic methods, while often multimodal treatments are necessary based on the patient's needs. The development of less invasive modalities for recurring treatment cycles is thus of critical significance. Herein, a light-activatable microparticle system was developed for localized, pulsatile delivery of anticancer drugs with simultaneous thermal ablation, by applying controlled ON-OFF thermal cycles using near-infrared laser irradiation. The system is composed of poly(caprolactone) microparticles of 200 μm size with incorporated molybdenum disulfide (MoS ₂ ) nanosheets as the photothermal agent and hydrophilic doxorubicin or hydrophobic violacein, as model drugs. Upon irradiation the nanosheets heat up to ≥50 °C leading to polymer matrix melting and release of the drug. MoS ₂ nanosheets exhibit high photothermal conversion efficiency and allow for application of low power laser irradiation for the system activation. A Machine Learning algorithm was applied to acquire optimal laser operation conditions; 0.4 W/cm ² laser power at 808 nm, 3-cycle irradiation, for 3 cumulative minutes. In a mouse subcutaneous model of 4T1 triple-negative breast cancer, 25 microparticles were intratumorally administered and after 3-cycle laser treatment the system conferred synergistic phototherapeutic and chemotherapeutic effect. Our on-demand, pulsatile synergistic treatment resulted in increased median survival up to 40 days post start of treatment compared to untreated mice, with complete eradication of the tumors at the primary site. Such a system could have potential for patients in need of recurring cycles of treatment on subcutaneous tumors.

GRAPHICAL ABSTRACT

Controlling the durability and optical properties of triplet-triplet annihilation upconversion nanocapsules

Deep penetration of high energy photons by direct irradiation is often not feasible due to absorption and scattering losses, which are generally exacerbated as photon energy increases. Precise generation of high energy photons beneath a surface can circumvent these losses and significantly transform optically controlled processes like photocatalysis or 3D printing. Using triplet-triplet annihilation upconversion (TTA-UC), a nonlinear process, we can locally convert two transmissive low energy photons into one high energy photon. We recently demonstrated the use of nanocapsules for high energy photon generation at depth, with durability within a variety of chemical environments due to the formation of a dense, protective silica shell that prevents content leakage and nanocapsule aggregation. Here, we show the importance of the feed concentrations of the tetraethylorthosilicate (TEOS) monomer and the methoxy poly(ethyleneglycol) silane (PEG-silane) ligand used to synthesize these nanocapsules using spectroscopic and microscopy characterizations. At optimal TEOS and PEG-silane concentrations, minimal nanocapsule leakage can be obtained which maximizes UC photoluminescence. We also spectroscopically study the origin of inefficient upconversion from UCNCs made using sub-optimal conditions to probe how TEOS and PEG-silane concentrations impact the equilibrium between productive shell growth and side product formation, like amorphous silica. Furthermore, this optimized fabrication protocol can be applied to encapsulate multiple TTA-UC systems and other emissive dyes to generate anti-Stokes or Stokes shifted emission, respectively. These results show that simple synthetic controls can be tuned to obtain robust, well-dispersed, bright upconverting nanoparticles for subsequent integration in optically controlled technologies.

Iron Oxide@Mesoporous Silica Core-Shell Nanoparticles as Multimodal Platforms for Magnetic Resonance Imaging, Magnetic Hyperthermia, Near-Infrared Light Photothermia, and Drug Delivery

The design of core-shell nanocomposites composed of an iron oxide core and a silica shell offers promising applications in the nanomedicine field, especially for developing efficient theranostic systems which may be useful for cancer treatments. This review article addresses the different ways to build iron oxide@silica core-shell nanoparticles and it reviews their properties and developments for hyperthermia therapies (magnetically or light-induced), combined with drug delivery and MRI imaging. It also highlights the various challenges encountered, such as the issues associated with in vivo injection in terms of NP-cell interactions or the control of the heat dissipation from the core of the NP to the external environment at the macro or nanoscale.

Remote control of transgene expression using noninvasive near-infrared irradiation

This study investigated whether noninvasive near-infrared (NIR) energy could be transduced into heat in deep-seated organs in which adenovirus type-5 vectors tend to accumulate, thereby activating heat shock protein (HSP) promoter-mediated transgene expression, without local administration of photothermal agents. NIR irradiation of the subdiaphragmatic and left dorsocranial part of the abdominal cavity of adult immunocompetent C3H/HeNRj mice with an 808-nm laser effectively increased the temperature of the irradiated regions of the liver and spleen, respectively, resulting in the accumulation of the heat-inducible HSP70 protein. Spatial control of transgene expression was achieved in the NIR-irradiated regions of the mice administered an adenoviral vector carrying a firefly luciferase (fLuc) coding sequence controlled by a human HSP70B promoter, as assessed by bioluminescence and immunohistochemistry analyses. Levels of reporter gene expression were modulated by controlling NIR power density. Spatial control of transgene expression through NIR-focused activation of the HSP70B promoter, as well as temporal regulation by administering rapamycin was achieved in the spleens of mice inoculated with an adenoviral vector encoding a rapamycin-dependent transactivator driven by the HSP70B promoter and an adenoviral vector carrying a fLuc coding sequence controlled by the rapamycin-activated transactivator. Mice that were administered rapamycin and exposed to NIR light expressed fLuc activity in the splenic region, whereas no activity was detected in mice that were only administered rapamycin or vehicle or only NIR-irradiated. Thus, in the absence of any exogenously supplied photothermal material, remote control of heat-induced transgene expression can be achieved in the liver and spleen by means of noninvasive NIR irradiation.

Combination d-Amino Acid and Photothermal Hydrogel for the Treatment of Prosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication requiring surgical intervention and prolonged antimicrobial treatment. The prevalence of PJI is on the rise, with an average incidence of 60,000 cases per year and a projected annual cost of $1.85 billion in the US. The underlying pathogenesis of PJI involves the formation of bacterial biofilms that protect the pathogen from the host immune response and antibiotics, making it difficult to eradicate such infections. Biofilms on implants are also resistant to mechanical brushing/scrubbing methods of removal. Since the removal of biofilms is currently only achievable by the replacement of the prosthesis, therapies aimed at eradicating biofilms while enabling retention of implants will revolutionize the management of PJIs. To address severe complications associated with biofilm-related infections on implants, we have developed a combination treatment that is based on a hydrogel nanocomposite system, containing d-amino acids (d-AAs) and gold nanorods, which can be delivered and transforms from a solution to a gel state at physiological temperature for sustained release of d-AAs and light-activated thermal treatment of infected sites. Using this two-step approach to utilize a near-infrared light-activated hydrogel nanocomposite system for thermal treatment, following initial disruption with d-AAs, we were able to successfully demonstrate in vitro the total eradication of mature Staphylococcus aureus biofilms grown on three-dimensional printed Ti-6Al-4V alloy implants. Using a combination of cell assays, computer-aided scanning electron microscopy analyses, and confocal microscopy imaging of the biofilm matrix, we could show 100% eradication of the biofilms using our combination treatment. In contrast, we were only able to see 25% eradication of the biofilms using the debridement, antibiotics, and implant retention method. Moreover, our hydrogel nanocomposite-based treatment approach is adaptable in the clinical setting and capable of combating chronic infections brought about by biofilms on medical implants.

Nanomaterials as multimodal photothermal agents (PTAs) against 'Superbugs'

Superbugs, also known as multidrug-resistant bacteria, have become a lethal and persistent threat due to their unresponsiveness toward conventional antibiotics. The main reason for this is that superbugs can rapidly mutate and restrict any foreign drug/molecule in their vicinity. Herein, nanomaterial-mediated therapies have set their path and shown burgeoning efficiency toward the ablation of superbugs. Notably, treatment modalities like photothermal therapy (PTT) have shown prominence in killing multidrug-resistant bacteria with their ability to generate local heat shock-mediated hyperthermia in such species. However, photothermal treatment has some serious limitations, such as high cost, complexity, and even toxicity to some extent. Hence, it is important to resolve such shortcomings of PTTs as they provide substantial tissue penetration. This is why multimodal PTTs have emerged and taken over this domain of research for the past few years. In this work, we have summarized and critically reviewed such exceptional works of recent times and provided a perspective to enhance their efficiencies. Profoundly, we discuss the design rationales of some novel photothermal agents (PTAs) and shed light on their mechanisms. Finally, challenges for PTT-derived multimodal therapy are presented, and capable synergistic bactericidal prospects are anticipated.

In Vivo Analysis of a Biodegradable Magnesium Alloy Implant in an Animal Model Using Near-Infrared Spectroscopy

Biodegradable magnesium-based implants offer mechanical properties similar to natural bone, making them advantageous over nonbiodegradable metallic implants. However, monitoring the interaction between magnesium and tissue over time without interference is difficult. A noninvasive method, optical near-infrared spectroscopy, can be used to monitor tissue's functional and structural properties. In this paper, we collected optical data from an in vitro cell culture medium and in vivo studies using a specialized optical probe. Spectroscopic data were acquired over two weeks to study the combined effect of biodegradable Mg-based implant disks on the cell culture medium in vivo. Principal component analysis (PCA) was used for data analysis. In the in vivo study, we evaluated the feasibility of using the near-infrared (NIR) spectra to understand physiological events in response to magnesium alloy implantation at specific time points (Day 0, 3, 7, and 14) after surgery. Our results show that the optical probe can detect variations in vivo from biological tissues of rats with biodegradable magnesium alloy "WE43" implants, and the analysis identified a trend in the optical data over two weeks. The primary challenge of in vivo data analysis is the complexity of the implant interaction near the interface with the biological medium.

Multicolor Light-Induced Immune Activation via Polymer Photocaged Cytokines

Cytokines act as potent, extracellular signals of the human immune system and can elicit striking treatment responses in patients with autoimmune disease, tissue damage, and cancer. Yet, despite their therapeutic potential, recombinant cytokine-mediated immune responses remain difficult to control as their administration is often systemic, whereas their intended sites of action are localized. To address the challenge of spatially and temporally constraining cytokine signals, we recently devised a strategy whereby recombinant cytokines are reversibly inactivated via chemical modification with photo-labile polymers that respond to visible LED light. Extending this approach to enable both in vivo and multicolor immune activation, here we describe a strategy whereby cytokines appended with heptamethine cyanine-polyethylene glycol are selectively re-activated ex vivo using tissue-penetrating near-infrared (NIR) light. We show that NIR LED light illumination of caged, pro-inflammatory cytokines restores cognate receptor signaling and potentiates the activity of T cell-engager cancer immunotherapies ex vivo. Using combinations of visible- and NIR-responsive cytokines, we further demonstrate multiwavelength optical control of T cell cytolysis ex vivo, as well as the ability to perform Boolean logic using multicolored light and orthogonally photocaged cytokine pairs as inputs and T cell activity as outputs. Together, this work demonstrates a novel approach to control extracellular immune cell signals using light, a strategy that in the future may improve our understanding of and ability to treat cancer and other diseases.

Nanoengineering Triplet-Triplet Annihilation Upconversion: From Materials to Real-World Applications

Using light to control matter has captured the imagination of scientists for generations, as there is an abundance of photons at our disposal. Yet delivering photons beyond the surface to many photoresponsive systems has proven challenging, particularly at scale, due to light attenuation via absorption and scattering losses. Triplet-triplet annihilation upconversion (TTA-UC), a process which allows for low energy photons to be converted to high energy photons, is poised to overcome these challenges by allowing for precise spatial generation of high energy photons due to its nonlinear nature. With a wide range of sensitizer and annihilator motifs available for TTA-UC, many researchers seek to integrate these materials in solution or solid-state applications. In this Review, we discuss nanoengineering deployment strategies and highlight their uses in recent state-of-the-art examples of TTA-UC integrated in both solution and solid-state applications. Considering both implementation tactics and application-specific requirements, we identify critical needs to push TTA-UC-based applications from an academic curiosity to a scalable technology.

Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies

Cognitive function is an important ability of the brain, but cognitive dysfunction can easily develop once the brain is injured in various neuropathological conditions or diseases. Photobiomodulation therapy is a type of noninvasive physical therapy that is gradually emerging in the field of neuroscience. Transcranial photobiomodulation has been commonly used to regulate neural activity in the superficial cortex. To stimulate deeper brain activity, advanced photobiomodulation techniques in conjunction with photosensitive nanoparticles have been developed. This review addresses the mechanisms of photobiomodulation on neurons and neural networks and discusses the advantages, disadvantages and potential applications of photobiomodulation alone or in combination with photosensitive nanoparticles. Photobiomodulation and its associated strategies may provide new breakthrough treatments for cognitive improvement.

Recent Advances in Localized Immunomodulation Technology: Application of NIR-PIT toward Clinical Control of the Local Immune System

Current immunotherapies aim to modulate the balance among different immune cell populations, thereby controlling immune reactions. However, they often cause immune overactivation or over-suppression, which makes them difficult to control. Thus, it would be ideal to manipulate immune cells at a local site without disturbing homeostasis elsewhere in the body. Recent technological developments have enabled the selective targeting of cells and tissues in the body. Photo-targeted specific cell therapy has recently emerged among these. Near-infrared photoimmunotherapy (NIR-PIT) has surfaced as a new modality for cancer treatment, which combines antibodies and a photoabsorber, IR700DX. NIR-PIT is in testing as an international phase III clinical trial for locoregional recurrent head and neck squamous cell carcinoma (HNSCC) patients (LUZERA-301, NCT03769506), with a fast-track designation by the United States Food and Drug Administration (US-FDA). In Japan, NIR-PIT for patients with recurrent head and neck cancer was conditionally approved in 2020. Although NIR-PIT is commonly used for cancer therapy, it could also be exploited to locally eliminate certain immune cells with antibodies for a specific immune cell marker. This strategy can be utilized for anti-allergic therapy. Herein, we discuss the recent technological advances in local immunomodulation technology. We introduce immunomodulation technology with NIR-PIT and demonstrate an example of the knockdown of regulatory T cells (Tregs) to enhance local anti-tumor immune reactions.

Near-Infrared-Triggered On-Demand Controlled Release of Adeno-Associated Virus from Alginate Hydrogel Microbeads with Heat Transducer for Gene Therapy

Gene therapy using adeno-associated virus (AAV) has potential as a radical treatment modality for genetic diseases such as sensorineural deafness. To establish clinical applications, it is necessary to avoid immune response to AAV by controlled release system of AAV. Here, a near-infrared (NIR)-triggered on-demand AAV release system using alginate hydrogel microbeads with a heat transducer is proposed. By using a centrifuge-based microdroplet shooting device, the microbeads encapsulating AAV with Fe₃ O₄ microparticles (Fe₃ O₄ -MPs) as a heat transducer are fabricated. Fe₃ O₄ -MPs generated heat by NIR enhanced the diffusion speed of the AAV, resulting in the AAV being released from the microbeads. By irradiating the microbeads encapsulating fluorescent polystyrene nanoparticles (FP-NPs) (viral model) with NIR, the fluorescence intensity decreased only for FP-NPs with a diameter of 20 nm and not for 100 or 200 nm, confirming that this system can release virus with a diameter of several tens of nanometers. By irradiating NIR to the AAV-encapsulating microbeads with Fe₃ O₄ -MPs, the AAV is released on demand, and gene transfection to cells by AAV is confirmed without loss of viral activity. The NIR-triggered AAV release system proposed in this study increases the number of alternatives for the method of drug release in gene therapy.

Near Infrared Photoimmunotherapy: A Review of Recent Progress and Their Target Molecules for Cancer Therapy

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed molecular targeted cancer treatment, which selectively kills cancer cells or immune-regulatory cells and induces therapeutic host immune responses by administrating a cancer targeting moiety conjugated with IRdye700. The local exposure to near-infrared (NIR) light causes a photo-induced ligand release reaction, which causes damage to the target cell, resulting in immunogenic cell death (ICD) with little or no side effect to the surrounding normal cells. Moreover, NIR-PIT can generate an immune response in distant metastases and inhibit further cancer attack by combing cancer cells targeting NIR-PIT and immune regulatory cells targeting NIR-PIT or other cancer treatment modalities. Several recent improvements in NIR-PIT have been explored such as catheter-driven NIR light delivery, real-time monitoring of cancer, and the development of new target molecule, leading to NIR-PIT being considered as a promising cancer therapy. In this review, we discuss the progress of NIR-PIT, their mechanism and design strategies for cancer treatment. Furthermore, the overall possible targeting molecules for NIR-PIT with their application for cancer treatment are briefly summarised.