A red light-controlled probiotic bio-system for in-situ gut-brain axis regulation.

Microbes regulate brain function through the gut-brain axis, deriving the technology to modulate the gut-brain axis in situ by engineered probiotics. Optogenetics offers precise and flexible strategies for controlling the functions of probiotics in situ. However, the poor penetration of most frequently used short wavelength light has limited the application of optogenetic probiotics in the gut. Herein, a red-light optogenetic gut probiotic was applied for drug production and delivery and regulation of the host behaviors. Firstly, a Red-light Optogenetic E. coli Nissle 1917 strain (ROEN) that could respond to red light and release drug product by light-controlled lysis was constructed. The remaining optical power of red light after 3 cm tissue was still able to initiate gene expression of ROEN and produce about approximately 3-fold induction efficiency. To give full play to the in vivo potential of ROEN, its responsive ability of the penetrated red light was tested, and its encapsulation was realized by PH-sensitive alginate microcapsules for further oral administration. The function of ROEN for gut-brain regulation was realized by releasing Exendin-4 fused with anti-neonatal Fc receptor affibody. Neuroprotection and behavioral regulation effects were evaluated in the Parkinson's disease mouse model, after orally administration of ROEN delivering Exendin-4 under optogenetic control in the murine gut. The red-light optogenetic probiotic might be a perspective platform for in situ drug delivery and gut-brain axis regulation.

Hydrogel microcapsules containing engineered bacteria for sustained production and release of protein drugs.

Subcutaneous administration of sustained-release formulations is a common strategy for protein drugs, which avoids first pass effect and has high bioavailability. However, conventional sustained-release strategies can only load a limited amount of drug, leading to insufficient durability. Herein, we developed microcapsules based on engineered bacteria for sustained release of protein drugs. Engineered bacteria were carried in microcapsules for subcutaneous administration, with a production-lysis circuit for sustained protein production and release. Administrated in diabetic rats, engineered bacteria microcapsules was observed to smoothly release Exendin-4 for 2 weeks and reduce blood glucose. In another example, by releasing subunit vaccines with bacterial microcomponents as vehicles, engineered bacterial microcapsules activated specific immunity in mice and achieved tumor prevention. The engineered bacteria microcapsules have potential to durably release protein drugs and show versatility on the size of drugs. It might be a promising design strategy for long-acting in situ drug factory.

Light-Sensitive Lactococcus lactis for Microbe-Gut-Brain Axis Regulating via Upconversion Optogenetic Micro-Nano System.

The discovery of the gut-brain axis has proven that brain functions can be affected by the gut microbiota's metabolites, so there are significant opportunities to explore new tools to regulate gut microbiota and thus work on the brain functions. Meanwhile, engineered bacteria as oral live biotherapeutic agents to regulate the host's healthy homeostasis have attracted much attention in microbial therapy. However, whether this strategy is able to remotely regulate the host's brain function in vivo has not been investigated. Here, we engineered three blue-light-responsive probiotics as oral live biotherapeutic agents. They are spatiotemporally delivered and controlled by the upconversion optogenetic micro-nano system. This micro-nano system promotes the small intestine targeting and production of the exogenous L. lactis in the intestines, which realizes precise manipulation of brain functions including anxiety behavior, Parkinson's disease, and vagal afferent. The noninvasive and real-time probiotic intervention strategy makes the communiation from the gut to the host more controllable, which will enable the potential for engineered microbes accurately and effectively regulating a host's health.

Precise Thermal Regulation of Engineered Bacteria Secretion for Breast Cancer Treatment In Vivo.

For the biomedical application of engineered bacteria, strictly regulating the function of engineered bacteria has always been the goal pursued. However, the existing regulation methods do not meet the needs of the in vivo application of engineered bacteria. Therefore, the exploration of the precise regulation of engineered bacteria is necessary. Herein, heat-sensitive engineered bacteria that can respond to thermal stimuli within 30 min were constructed, and the precise control of functions was verified in the intestines of various model organisms (including C. elegans, bees, and mice). Subsequently, heat-sensitive engineered bacteria were shown to colonize the mouse tumor microenvironment. Finally, thermal stimulation was proven to control engineered bacteria to produce the therapeutic protein tumor necrosis factor α (TNF-α) in the tumor. After three heat stimulation treatments, the growth of the tumor was significantly inhibited, suggesting that heat can be used as a strategy to precisely control engineered bacteria in vivo.

"Magnetism-Optogenetic" System for Wireless and Highly Sensitive Neuromodulation.

Neuromodulation is becoming more and more important in studying brain function, disease treatment, and brain-computer interfaces. However, traditional regulation methods cannot effectively achieve both wireless regulation and highly sensitive response, which are essential factors in neuromodulation. In this paper, a "magnetism-optogenetic" system is constructed, which uses a magnetic field to drive mechanoluminescent materials (ZnS:Cu) to generate light, thus stimulating photogenetic proteins. This system effectively combines the wireless magnetic regulation with the high sensitivity of optogenetics. The results show that the luminous intensity of this system changes with the power of an external magnetic field. In addition, under the continuous stimulation of the wireless magnetic field, this system can activate hippocampal-related neural responses and induce the expression of C-fos. In the end, this system can further regulate the movement behavior of rats with C1V1 protein expression in the primary motor cortex. This new magnetism-optogenetic system will provide an excellent reference for wireless and highly sensitive neuromodulation.

NIR light-responsive bacteria with live bio-glue coatings for precise colonization in the gut.

Recombinant bacterial colonization plays an indispensable role in disease prevention, alleviation, and treatment. Successful application mainly depends on whether bacteria can efficiently spatiotemporally colonize the host gut. However, a primary limitation of existing methods is the lack of precise spatiotemporal regulation, resulting in uncontrolled methods that are less effective. Herein, we design upconversion microgels (UCMs) to convert near-infrared light (NIR) into blue light to activate recombinant light-responsive bacteria (Lresb) in vivo, where autocrine "functional cellular glues" made of adhesive proteins assist Lresb inefficiently colonizing the gut. The programmable engineering platform is further developed for the controlled and effective colonization of Escherichia coli Nissle 1917 (EcN) in the gut. The colonizing bacteria effectively alleviate DSS-induced colitis in mice. We anticipate that this approach could facilitate the clinical application of engineered microbial therapeutics to accurately and effectively regulate host health.

Optotheranostic Nanosystem with Phone Visual Diagnosis and Optogenetic Microbial Therapy for Ulcerative Colitis At-Home Care.

Ulcerative colitis (UC) is a relapsing disorder characterized by chronic inflammation of the intestinal tract. However, the home care of UC based on remote monitoring, due to the operational complexity and time-consuming procedure, restrain its widespread applications. Here we constructed an optotheranostic nanosystem for self-diagnosis and long-acting mitigations of UC at home. The system included two major modules: (i) A disease prescreening module mediated by smartphone optical sensing. (ii) Disease real-time intervention module mediated by an optogenetic engineered bacteria system. Recombinant Escherichia coli Nissle 1917 (EcN) secreted interleukin-10 (IL-10) could downregulate inflammatory cascades and matrix metalloproteinases; it is a candidate for use in the therapeutic intervention of UC. The results showed that the Detector was able to analyze, report, and share the detection results in less than 1 min, and the limit of detection was 15 ng·mL-1. Besides, the IL-10-secreting EcN treatment suppressed the intestinal inflammatory response in UC mice and protected the intestinal mucosa against injury. The optotheranostic nanosystems enabled solutions to diagnose and treat disease at home, which promotes a mobile health service development.

A Multichannel Flexible Optoelectronic Fiber Device for Distributed Implantable Neurological Stimulation and Monitoring.

Optical fibers made of polymeric materials possess high flexibility that can potentially integrate with flexible electronic devices to realize complex functions in biology and neurology. Here, a multichannel flexible device based on four individually addressable optical fibers transfer-printed with flexible electronic components and controlled by a wireless circuit is developed. The resulting device offers excellent mechanics that is compatible with soft and curvilinear tissues, and excellent diversity through switching different light sources. The combined configuration of optical fibers and flexible electronics allows optical stimulation in selective wavelengths guided by the optical fibers, while conducting distributed, high-throughput biopotential sensing using the flexible microelectrode arrays. The device has been demonstrated in vivo with rats through optical stimulation and simultaneously monitoring of spontaneous/evoked spike signals and local field potentials using 32 microelectrodes in four brain regions. Biocompatibility of the device has been characterized by behavior and immunohistochemistry studies, demonstrating potential applications of the device in long-term animal studies. The techniques to integrate flexible electronics with optical fibers may inspire the development of more flexible optoelectronic devices for sophisticated applications in biomedicine and biology.

CRISPR-dcas9 Optogenetic Nanosystem for the Blue Light-Mediated Treatment of Neovascular Lesions.

Vascular endothelial growth factor (VEGF) is the key regulator in neovascular lesions. The anti-VEGF injection is a major way to relieve retinal neovascularization and treat these diseases. However, current anti-VEGF therapeutics show significant drawbacks. The reason is the inability to effectively control its therapeutic effect. Therefore, how to controllably inhibit the VEGF target is a key point for preventing angiogenesis. Here, a CRISPR-dCas9 optogenetic nanosystem was designed for the precise regulation of pathologic neovascularization. This system is composed of a light-controlled regulatory component and transcription inhibition component. They work together to controllably and effectively inhibit the target gene's VEGF. The opto-CRISPR nanosystem achieved precise regulation according to individual differences, whereby the expression and interaction of gene was activated by light. The following representative model laser-induced choroid neovascularization and oxygen-induced retinopathy were taken as examples to verify the effect of this nanosystem. The results showed that the opto-CRISPR nanosystem was more efficacious in the light control group (NV area effectively reduced by 41.54%) than in the dark control group without light treatment. This strategy for the CRISPR-optogenetic gene nanosystem led to the development of approaches for treating severe eye diseases. Besides, any target gene of interest can be designed by merely replacing the guide RNA sequences in this system, which provided a method for light-controlled gene transcriptional repression.

Author Correction: Upconversion optogenetic micro-nanosystem optically controls the secretion of light-responsive bacteria for systemic immunity regulation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Upconversion optogenetic micro-nanosystem optically controls the secretion of light-responsive bacteria for systemic immunity regulation.

Chemical molecules specifically secreted into the blood and targeted tissues by intestinal microbiota can effectively affect the associated functions of the intestine especially immunity, representing a new strategy for immune-related diseases. However, proper ways of regulating the secretion metabolism of specific strains still remain to be established. In this article, an upconversion optogenetic micro-nanosystem was constructed to effectively regulate the specific secretion of engineered bacteria. The system included two major modules: (i) Modification of secretory light-responsive engineered bacteria. (ii) Optical sensing mediated by upconversion optogenetic micro-nanosystem. This system could regulate the efficient secretion of immune factors by engineered bacteria through optical manipulation. Inflammatory bowel disease and subcutaneously transplanted tumors were selected to verify the effectiveness of the system. Our results showed that the endogenous factor TGF-ß1 could be controllably secreted to suppress the intestinal inflammatory response. Additionally, regulatory secretion of IFN-γ was promoted to slow the progression of B16F10 tumor.

Cyanobacteria-Based Bio-Oxygen Pump Promoting Hypoxia-Resistant Photodynamic Therapy.

Hypoxia not only alters tumor microenvironment but leads to the tumor progression and metastasis as well as drug resistance. As a promising strategy, photodynamic therapy (PDT) can inhibit tumor by catalyzing O2 to cytotoxic reactive oxygen species. However, its effects were limited by hypoxia and in turn deteriorate hypoxia due to O2 consumption. Hereon, aiming to alleviate hypoxia and promote PDT, a bio-oxygen pump was created based on cyanobacteria, which are the only prokaryotic organisms performing oxygenic photosynthesis. Detailly, controlled-release PDT via loading indocyanine green into mesoporous silica nanoparticles was established. Then bio-oxygen pump based on a fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 was tested and further packaged together with PDT to create an injectable hydrogel. The packaged hydrogel showed stable oxygen production and synergetic therapy effect especially toward hypoxia 4T1 cells in vitro. More importantly, strong in vivo therapeutic effect reaching almost 100% inhibition on tumor tissues was realized using PDT equipped with oxygen pump, with only negligible in vivo side effect on healthy mice from S. elongatus UTEX 2973. The new photo-oxygen-dynamic therapy presented here provided a promising strategy against hypoxia-resistant tumor and may worth further modifications for therapeutic application.

An efficient delivery of photosensitizers and hypoxic prodrugs for a tumor combination therapy by membrane camouflage nanoparticles.

Photodynamic therapy (PDT) is an oxygen-dependent, non-invasive cancer treatment. The hypoxia in the tumor environment limits the therapeutic effects of PDT. The combined delivery of photosensitizers and hypoxic prodrugs is expected to improve the efficacy of tumor treatment. In this paper, an erythrocyte and tumor cell membrane camouflage nanocarrier co-loaded with a photosensitizer (indocyanine green) and a hypoxic prodrug (tirapazamine) were used to combine PDT with chemotherapy. The system achieved less macrophage clearance through erythrocyte membranes and tumor-targeted tumor cell membranes, thereby inducing cell death and increasing tumor environment hypoxia by NIR irradiation of photosensitizers. Furthermore, the hypoxic environment activated TPZ to kill more tumor cells. In vivo results showed that the tumor inhibition rate of the drug-loaded nanoparticles increased from 34% to 64% after membrane modification. Moreover, the tumor inhibition rate of the photodynamic treatment group alone was only 47%, and the tumor inhibition rate after the combination was 1.3 times that of photodynamic therapy alone. Our platform is expected to contribute to the further application of cancer combination therapy.

Near-infrared light remotely up-regulate autophagy with spatiotemporal precision via upconversion optogenetic nanosystem.

In vivo noninvasively manipulating biological functions by the mediation of biosafe near infrared (NIR) light is becoming increasingly popular. For these applications, upconversion rare-earth nanomaterial holds great promise as a novel photonic element, and has been widely adopted in optogenetics. In this article, an upconversion optogenetic nanosystem that was promised to achieve autophagy up-regulation with spatiotemporal precision was designed. The implantable, wireless, recyclable, less-invasive and biocompatible system worked via two separated parts: blue light-receptor optogenetics-autophagy upregulation plasmids, for protein import; upconversion rods-encapsulated flexible capsule (UCRs-capsule), for converting tissue-penetrative NIR light into local visible blue light. Results validated that this system could achieve up-regulation of autophagy in vitro (in both HeLa and 293T cell lines) and remotely penetrate tissue (∼3.5 mm) in vivo. Since autophagy serves at a central position in intracellular signalling pathways, which is correlative with diverse pathologies, we expect that this method could establish an upconversion material-based autophagy up-regulation strategy for fundamental and clinical applications.

Near-Infrared Light-Excited Upconverting Persistent Nanophosphors in Vivo for Imaging-Guided Cell Therapy.

Optical imaging for biological applications is in need of more sensitive tool. Persistent luminescent nanophosphors enable highly sensitive in vivo optical detection and almost completely avoid tissue autofluorescence. Nevertheless, the actual persistent luminescent nanophosphors necessitate ex vivo activation before systemic operation, which severely restricted the use of long-term imaging in vivo. Hence, we introduced a novel generation of optical nanophosphors, based on (Zn2SiO4:Mn):Y3+, Yb3+, Tm3+ upconverting persistent luminescent nanophosphors; these nanophosphors can be excited in vivo through living tissues by highly penetrating near-infrared light. We can trace labeled tumor therapeutic macrophages in vivo after endocytosing these nanophosphors in vitro and follow macrophages biodistribution by a simple whole animal optical detection. These nanophosphors will open novel potentials for cell therapy research and for a variety of applications in diagnosis in vivo.

Targeted delivery of tungsten oxide nanoparticles for multifunctional anti-tumor therapy via macrophages.

Tumor-associated macrophages are highly versatile effector cells that have been used to kill tumor cells. Herein, the macrophages as cell-based biocarriers are used for the targeted delivery of photothermal reagents for promoting the efficiency of killing tumor cells by activating the anti-tumor immune response and photothermal therapy (PTT). In this design, macrophages cause the phagocytosis of tumor cells and activate the anti-tumor immune response by secreting plenty of cytokines. Meanwhile, to improve the tumor-killing effect and track the collaborative therapy system in vivo, a novel nanoplatform based on tungsten oxide (W18O49, WO) nanoparticles and fluorescent dyes loaded in polylactic-co-glycolic acid (PLGA) for PTT has been successfully constructed. Subsequently, the nanoparticles are swallowed by macrophages acting as cell-based biocarriers to target the tumor and promote solid tumor ablation in vivo in animal experiments. This system is expected to bring a huge application potential in the visually guided dual-modal therapeutic platform for tumor targeting therapy in vivo.

Materials and Techniques for Implantable Nutrient Sensing Using Flexible Sensors Integrated with Metal-Organic Frameworks.

The combination of novel materials with flexible electronic technology may yield new concepts of flexible electronic devices that effectively detect various biological chemicals to facilitate understanding of biological processes and conduct health monitoring. This paper demonstrates single- or multichannel implantable flexible sensors that are surface modified with conductive metal-organic frameworks (MOFs) such as copper-MOF and cobalt-MOF with large surface area, high porosity, and tunable catalysis capability. The sensors can monitor important nutriments such as ascorbicacid, glycine, l-tryptophan (l-Trp), and glucose with detection resolutions of 14.97, 0.71, 4.14, and 54.60 × 10-6 m, respectively. In addition, they offer sensing capability even under extreme deformation and complex surrounding environment with continuous monitoring capability for 20 d due to minimized use of biological active chemicals. Experiments using live cells and animals indicate that the MOF-modified sensors are biologically safe to cells, and can detect l-Trp in blood and interstitial fluid. This work represents the first effort in integrating MOFs with flexible sensors to achieve highly specific and sensitive implantable electrochemical detection and may inspire appearance of more flexible electronic devices with enhanced capability in sensing, energy storage, and catalysis using various properties of MOFs.

Near-Infrared Light Triggered Upconversion Optogenetic Nanosystem for Cancer Therapy.

In vivo the application of optogenetic manipulation in deep tissue is seriously obstructed by the limited penetration depth of visible light that is continually applied to activate a photoactuator. Herein, we designed a versatile upconversion optogenetic nanosystem based on a blue-light-mediated heterodimerization module and rare-earth upconversion nanoparticles (UCNs). The UCNs worked as a nanotransducer to convert external deep-tissue-penetrating near-infrared (NIR) light to local blue light to noninvasively activate photoreceptors for optogenetic manipulation in vivo. In this, we demonstrated that deeply penetrating NIR light could be used to control the apoptotic signaling pathway of cancer cells in both mammalian cells and mice by UCNs. We believe that this interesting NIR-light-responsive upconversion optogenetic nanotechnology has significant application potentials for both basic research and clinical applications in vivo.

A visual guide to gene/optothermal synergy therapy nanosystem using tungsten oxide.

Combination of gene therapy and photothermal therapy (PTT) has drawn much attention in cancer therapy in recent years. However, this joint treatment process lacks fluorescence imaging visualization guidance that limits its clinical applications in oncotherapy. Herein, we report the use of gene therapy and tungsten oxide (W18O49, WO) synthetized with template method for combined PTT of cancer. In this system, a novel nanoplatform, with Bax gene, WO and indocyanine green (ICG) loaded in mesoporous silica nanoparticle had been successfully constructed, which was used as the near-infrared imaging-guided gene/optothermal multi-modal oncotherapy. These nanoparticles could achieve a synergistic therapy effect of gene therapy and PTT for tumor under 808nm near-infrared (NIR) laser excitation. In vivo animal experiments showed that they could cause solid tumor regression under 808nm NIR light irradiation, revealing the potential of these nanocomposites as a fluorescence imaging-guided multi-modal therapeutic nanosystem for tumor visual synergistic treatment.

Near-infrared persistent luminescence phosphors ZnGa2O4:Cr3+ as an accurately tracker to photothermal therapy in vivo for visual treatment.

The photothermal therapy agents induced by 808 nm near infrared light laser have good potential for photothermal therapy (PTT) in vivo, with the advantages of harmless treatment, minimally invasion, high efficiency and deep tissue penetration. For the traditional photothermal therapy agents, however, it was impossible to track them in vivo because of the low signal-to-noise ratio, so we cannot conduct the extra near infrared light laser to radiate tumors sites accurately. Herein, we introduce a new complex: indocyanine green (ICG), near-infrared persistent luminescence (PL) phosphors ZnGa2O4:Cr3+ (ZGC) and mesoporous silica nanoparticles (MSNs) (ICG@mZGC nanoparticles) were assembled for long-lasting optical imaging to guide PTT. The results revealed that the novel nanoparticle, ICG@mZGC, could lower signal-to-noise ratio, enable highly sensitive optical detection during optical imaging-guided PTT and perform a good effect of photothermal therapy in vivo, and thus providing possibilities for mZGC to improve the localization precision of tumor sites in photothermal therapy in the body.