Upconversion dual-photosensitizer-expressing bacteria for near-infrared monochromatically excitable synergistic phototherapy

Synergistic phototherapy stands for superior treatment prospects than a single phototherapeutic modality. However, the combined photosensitizers often suffer from incompatible excitation mode, limited irradiation penetration depth, and lack of specificity. We describe the development of upconversion dual-photosensitizer-expressing bacteria (UDPB) for near-infrared monochromatically excitable combination phototherapy. UDPB are prepared by integrating genetic engineering and surface modification, in which bacteria are encoded to simultaneously express photothermal melanin and phototoxic KillerRed protein and the surface primary amino groups are derived to free thiols for biorthogonal conjugation of upconversion nanoparticles. UDPB exhibit a near-infrared monochromatic irradiation-mediated dual-activation characteristic as the photothermal conversion of melanin can be initiated directly, while the photodynamic effect of KillerRed can be stimulated indirectly by upconverted visible light emission. UDPB also show living features to colonize hypoxic lesion sites and inhibit pathogens via bacterial community competition. In two murine models of solid tumor and skin wound infection, UDPB separately induce robust antitumor response and a rapid wound healing effect.

Hydrogen Sulfide: An Emerging Precision Strategy for Gas Therapy

Advances in nanotechnology have enabled the rapid development of stimuli-responsive therapeutic nanomaterials for precision gas therapy. Hydrogen sulfide (H₂ S) is a significant gaseous signaling molecule with intrinsic biochemical properties, which exerts its various physiological effects under both normal and pathological conditions. Various nanomaterials with H₂ S-responsive properties, as new-generation therapeutic agents, are explored to guide therapeutic behaviors in biological milieu. The cross disciplinary of H₂ S is an emerging scientific hotspot that studies the chemical properties, biological mechanisms, and therapeutic effects of H₂ S. This review summarizes the state-of-art research on H₂ S-related nanomedicines. In particular, recent advances in H₂ S therapeutics for cancer, such as H₂ S-mediated gas therapy and H₂ S-related synergistic therapies (combined with chemotherapy, photodynamic therapy, photothermal therapy, and chemodynamic therapy) are highlighted. Versatile imaging techniques for real-time monitoring H₂ S during biological diagnosis are reviewed. Finally, the biosafety issues, current challenges, and potential possibilities in the evolution of H₂ S-based therapy that facilitate clinical translation to patients are discussed.

Immunosorbent assay based on upconversion nanoparticles controllable assembly for simultaneous detection of three antibiotics

The abuse of antibiotics leads to an increase in resistant strains, which in turn leads to the development of superbugs that pose great difficulties for the treatment of human diseases. A high-throughput and highly sensitive avidin biotin complex immunosorbent assay based on upconversion nanoparticles controllable assembly (ABC-ULISA) for the detection of antibiotics was developed, which enabled accurate quantitative detection in a shorter period of time. Streptavidin and biotin-labeled upconversion nanoparticles form avidin-biotin-upconversion complex, which was then combined with biotinylated antibody to achieve double amplification of the signal, further improving detection sensitivity. Upconversion nanoparticles with 808 nm excitation provide better penetration without the need for an external source. The 96-well enzyme-linked plate was used as a detection platform to meet the high-throughput needs. ABC-ULISA was used to simultaneously detect three antibiotics with a limit of detection of 0.15 ng/mL for sulfamethazine, 0.03 ng/mL for sarafloxacin, and 0.05 ng/mL for tetracycline. The detection limit of ABC-ULISA was much lower than the traditional ELISA and ordinary ULISA. Moreover, ABC-ULISA was also versatile, and the corresponding target can be detected by changing different antibodies. The results were stable and reliable, and the equipment could be miniaturized, which was expected to be commercialized and on-site.

Mesoporous Carbon Nanoparticles as Multi-functional Carriers for Cancer Therapy Compared with Mesoporous Silica Nanoparticles

Mesoporous carriers have been widely used to deliver anticancer drugs due to their unique characteristics. In this work, mesoporous silica nanoparticles (MSN) and mesoporous carbon nanoparticles (MCN) with substantially similar and uniform particle size, specific surface area, and pore size were prepared to compare the photothermal effect, drug loading efficiencies (LE), and drug release properties. In order to improve the dispersion stability and biocompatibility of the carriers, MSN and MCN were grafted with PEG, respectively. The NIR-induced photothermal effect results indicated that MCN had a brilliant photothermal conversion efficiency due to its strong near-infrared absorption capacity, while MSN had no photothermal conversion capability. Moreover, LE of DOX in DOX/MCN-PEG reached 36.58%, higher than that in DOX/MSN-PEG, which was ascribed to non-covalent interaction of π-π stacking and electrostatic attraction. In addition, compared to DOX/MSN-PEG, DOX/MCN-PEG had a significantly increased release rate under NIR laser irradiation due to excellent photothermal conversion capability of MCN-PEG. Furthermore, cell viability assay and cellular uptake experiment results demonstrated that DOX/MCN-PEG showed a synergistic therapeutic effect in the combination of chemotherapy and phototherapy, with a combination index (CI) of 0.238.

Prussian blue-coated lanthanide-doped core/shell/shell nanocrystals for NIR-II image-guided photothermal therapy

Lanthanide-doped nanoparticles have long been stereotyped for optical luminescence bioimaging. However, they are known to be unable to produce therapeutic abilities. Here, we describe a lanthanide-based theranostic agent, namely, prussian blue (PB)-coated NaErF4@NaYF4@NaNdF4 core/shell/shell nanocrystals encapsulated in a phospholipid PEG micelle (PEG-CSS@PB), which showed switched imaging and hyperthermia abilities under distinct near infrared (NIR) light activation. The erbium (Er3+)-enriched inner core nanocrystals (NaErF4) enabled the emission of tissue-penetrating luminescence (1525 nm) in the second biological window (NIR-II, 1000-1700 nm), which endowed high-resolution optical imaging of the blood vessels and tumors under ∼980 nm excitation. High neodymium (Nd3+) concentrations in the epitaxial outer NaNdF4 shell introduced maximum cross relaxation processes that converted the absorbed NIR light (∼808 nm) into heat at high efficiencies, thus providing abilities for photothermal therapy (PTT). Importantly, the coated Prussian blue (PB) increased light absorption by about 10-fold compared to the composite free of PB, thus entailing a high light-to-heat conversion efficiency of ∼50.5%. This commensurated with that of well-established gold nanorods. As a result, the PEG-CSS@PB nanoparticles with MTT-determined low toxicities resulted in ∼80% death of HeLa cells at a dose of 600 μg mL-1 under 808 nm laser irradiance (1 W cm-2) for 10 min. Moreover, utilizing the same light dose, a single PTT treatment in tumor-bearing BALB/c mice shrunk the tumor size by ∼12-fold compared to the tumors without treatment. Our results, here, constituted a solid step forward to entitle lanthanide-based nanoparticles as theranostic agents in nanomedicine studies.

Enhancement of ultralow-intensity NIR light-triggered photodynamic therapy based on exo- and endogenous synergistic effects through combined glutathione-depletion chemotherapy

Although photodynamic therapy (PDT), which uses a photosensitizer (PS) to generate toxic reactive oxygen species (ROS) upon laser irradiation to kill cancer cells, has been widely applied, the relatively high laser intensity required causes photodamage to healthy neighboring cells and limits its success. Furthermore, glutathione (GSH, an antioxidant) is overexpressed in cancer cells, which can scavenge the generated ROS, thus lowering PDT efficacy. Herein, ultralow-intensity near-infrared (NIR) light-triggered PDT was developed and enhanced through combined GSH-depletion chemotherapy (Chemo) based on exo- and endogenous synergistic effects. Highly emissive upconversion nanoparticles (UCNPs) were prepared and coated with a solid silica shell, which was used to encapsulate the PS rose bengal and bond the drug camptothecin with a disulfide-bond linker. The combination of highly emissive UCNPs and a matchable PS with an optimized loading dosage enabled ROS to be generated for PDT even upon 808 nm laser irradiation with ultralow intensity (0.30 W cm^-2). According to the American National Standard, this laser intensity is below the maximum permissible exposure of skin (MPE, 0.33 W cm^-2). Once the prepared nanoparticles endocytosed and encountered intracellular GSH, the disulfide-bond linker was cleaved by GSH, leading to drug release and GSH depletion. PDT was therefore simultaneously enhanced through the exogenous synergic effect of Chemo (namely, the "1 + 1 > 2" therapeutic effect) and the endogenous synergic effect as a result of GSH depletion. It was proven both in vitro and in vivo that this novel dual-synergistic Chemo/PDT system exhibits remarkable therapeutic efficacy with minimal photodamage to healthy neighboring cells.

Gold nanoparticles modified hollow carbon system for dual-responsive release and chemo-photothermal synergistic therapy of tumor

Thermochemotherapy has shown a synergistic anti-cancer efficiency and can enhance the therapeutic effect of simple chemotherapy. The photothermal conversion characteristics of carriers are vital in thermo-chemotherapy. Therefore, hollow mesoporous carbon (HMC) with excellent heating efficiency and a large specific surface area was used to ensure the high loading capacity. Next, approximately 4 nm spherical gold nanoparticles (NPs) were employed as gatekeepers of the tunnels of HMC by Au-S bonds, which have the same size as HMC mesopores. Additionally, the gold NPs could avoid the premature release of the drug and enhance the photothermal properties of the delivery system. The surface of the carriers was modified with polyethylene glycol (PEG) to increase the biocompatibility and dispersity of doxorubicin (DOX) loaded DOX/HMC-Au@PEG. DOX release was markedly accelerated in the presence of glutathione (GSH) and near-infrared (NIR), indicating that the system had redox and NIR dual-triggered drug release characteristics. Cytotoxicity experiments proved that combined therapy induced the highest cell killing level. Additionally, the combination index (CI) of DOX/HMC-Au@PEG was 0.452, indicating the synergistic effect of chemotherapy and photo-thermal therapy (PTT). In vivo antitumor experiments were also carried out and showed the same trend. In general, the results of this study indicated that DOX/HMC-Au@PEG has great potential in dual-triggered drug delivery and thermochemotherapy.

Theranostic nanocomposite from upconversion luminescent nanoparticles and black phosphorus nanosheets

An anti-cancer campaign might not be easily achieved through a single therapeutic modality. Collaboration of multimodal therapies and diagnosis could be vital to win the battle against cancer. In this context, we synthesized a multifunctional theranostic nanocomposite (UCNP–BPNS) from upconversion nanoparticles (UCNP) and black phosphorus nanosheets (BPNS) for synergistic photothermal/photodynamic therapies in vitro and dual modal imaging. Core–shell UCNP (NaYF₄:Yb,Er@NaGdF₄) and BPNS were synthesized using solvo-thermal and liquid exfoliation methods, respectively, and then covalently conjugated after UCNP was modified with polyacrylic acid and BPNS with methoxypolyethylene glycol amine. The experimental results validate that the nanocomposite exhibited a good photothermal therapy (PTT) effect under 808 nm laser irradiation, endorsing the apparent heat conversion effect of BPNS. Besides, a very good photodynamic therapy (PDT) effect was achieved under 980 nm laser irradiation of the nanocomposite due to Förster resonance energy transfer from UCNP to BPNS that generated singlet oxygen (¹O₂). The synergistic PTT/PDT therapeutic effect provided by UCNP–BPNS under simultaneous 808 and 980 nm laser irradiation was significantly higher than either PTT or PDT alone. Furthermore, due to the merit of the outer shell coated on the surface of the core of UCNP, the nanocomposite exhibited good potential for magnetic resonance and upconversion luminescence imaging. These results demonstrated that our multifunctional nanocomposite has promising theranostic efficacy under near infrared laser irradiation.

We successfully synthesized a multifunctional theranostic nanocomposite from upconversion nanoparticles and black phosphorus nanosheets for synergistic photothermal/photodynamic therapies in vitro and dual modal imaging.

Diversified copper sulfide (Cu2-xS) micro-/nanostructures: a comprehensive review on synthesis, modifications and applications

As a significant metal chalcogenide, copper sulfide (Cu_2-xS, 0 < x < 1), with a unique semiconducting and nontoxic nature, has received significant attention over the past few decades. Extensive investigations have been employed to the various Cu_2-xS micro-/nanostructures owing to their excellent optoelectronic behavior, potential thermoelectric properties, and promising biomedical applications. As a result, micro-/nanostructured Cu_2-xS with well-controlled morphologies, sizes, crystalline phases, and compositions have been rationally synthesized and applied in the fields of photocatalysis, energy conversion, in vitro biosensing, and in vivo imaging and therapy. However, a comprehensive review on diversified Cu_2-xS micro-/nanostructures is still lacking; therefore, there is an imperative need to thoroughly highlight the new advances made in function-directed Cu_2-xS-based nanocomposites. In this review, we have summarized the important progress made in the diversified Cu_2-xS micro-/nanostructures, including that in the synthetic strategies for the preparation of 0D, 1D, 2D, and 3D micro-/nanostructures (including polyhedral, hierarchical, hollow architectures, and superlattices) and in the development of modified Cu_2-xS-based composites for enhanced performance, as well as their various applications. Furthermore, the present issues and promising research directions are briefly discussed.

808-nm-Light-Excited Lanthanide-Doped Nanoparticles: Rational Design, Luminescence Control and Theranostic Applications

808 nm-light-excited lanthanide (Ln³⁺ )-doped nanoparticles (LnNPs) hold great promise for a wide range of applications, including bioimaging diagnosis and anticancer therapy. This is due to their unique properties, including their minimized overheating effect, improved penetration depth, relatively high quantum yields, and other common features of LnNPs. In this review, the progress of 808 nm-excited LnNPs is reported, including their i) luminescence mechanism, ii) luminescence enhancement, iii) color tuning, iv) diagnostic and v) therapeutic applications. Finally, the future outlook and challenges of 808 nm-excited LnNPs are presented.

Near-infrared light-mediated LA-UCNPs@SiO2-C/HA@mSiO2-DOX@NB nanocomposite for chemotherapy/PDT/PTT and imaging

Upon 980 nm light irradiation, multiple-emission can not only induce chemotherapy/PDT/PTT but also imaging.

New advances on the marrying of UCNPs and photothermal agents for imaging-guided diagnosis and the therapy of tumors

This review primarily focuses on the new advances in the design and theranostic applications of rare earth upconversion nanoparticles (UCNPs)–NIR photothermal absorbers multifunctional nanoplatforms.

A highly stable and biocompatible optical bioimaging nanoprobe based on carbon nanospheres

In this report, a facile one-step synthesis strategy has been developed for producing fluorescent carbon nanospheres (CNs) using lactobionic acid (LBA) as a precursor.