Energy transfer facilitated near infrared fluorescence imaging and photodynamic therapy of tumors

Alkaline Phosphatase-Instructed Peptide Assemblies for Imaging and Therapeutic Applications

Self-assembly, a powerful strategy for constructing highly stable and well-ordered supramolecular structures, widely exists in nature and in living systems. Peptides are frequently used as building blocks in the self-assembly process due to their advantageous characteristics, such as ease of synthesis, tunable mechanical stability, good biosafety, and biodegradability. Among the initiators for peptide self-assembly, enzymes are excellent candidates for guiding this process under mild reaction conditions. As a crucial and commonly used biomarker, alkaline phosphatase (ALP) cleaves phosphate groups, triggering a hydrophilicity-to-hydrophobicity transformation that induces peptide self-assembly. In recent years, ALP-instructed peptide self-assembly has made breakthroughs in biological imaging and therapy, inspiring the development of self-assembly biomaterials for diagnosis and therapeutics. In this review, we highlight the most recent advancements in ALP-instructed peptide assemblies and provide perspectives on their potential impact. Finally, we briefly discuss the ongoing challenges for future research in this field.

Three-in-One: Molecular Engineering of D-A-π-A Featured Type I and Type II Near-Infrared AIE Photosensitizers for Efficient Photodynamic Cancer Therapy and Bacteria Killing

Bacterial infections are closely correlated with the genesis and progression of cancer, and the elimination of cancer-related bacteria may improve the efficacy of cancer treatment. However, the combinatorial therapy that utilizes two or more chemodrugs will increase potential adverse effects. Image-guided photodynamic therapy is a highly precise and potential therapy to treat tumor and microbial infections. Herein, four donor-acceptor-π-bridge-acceptor (D-A-π-A) featured near-infrared (NIR) aggregation-induced emission luminogens (AIEgens) (TQTPy, TPQTPy, TQTC, and TPQTC) with type I and type II reaction oxygen species (ROS) generation capabilities are synthesized. Notably, TQTPy shows mitochondria targeted capacity, the best ROS production efficiency, long-term tumor retention capacity, and more importantly, the three-in-one fluorescence imaging guided therapy against both tumor and microbial infections. Both in vitro and in vivo results validate that TQTPy performs well in practical biomedical application in terms of NIR-fluorescence imaging-guided photodynamic cancer diagnosis and treatment. Moreover, the amphiphilic and positively charged TQTPy is able to specific and ultrafast discrimination and elimination of Gram-positive (G+) Staphylococcus aureus from Gram-negative (G-) Escherichia coli and normal cells. This investigation provides an instructive way for the construction of three-in-one treatment for image-guided photodynamic cancer therapy and bacteria elimination.

A photoactivatable upconverting nanodevice boosts the lysosomal escape of PROTAC degraders for enhanced combination therapy

PROteolysis TArgeting Chimeras have received increasing attention due to their capability to induce potent degradation of various disease-related proteins. However, the effective and controlled cytosolic delivery of current small-molecule PROTACs remains a challenge, primarily due to their intrinsic shortcomings, including unfavorable solubility, poor cell permeability, and limited spatiotemporal precision. Here, we develop a near-infrared light-controlled PROTAC delivery device (abbreviated as USDPR) that allows the efficient photoactivation of PROTAC function to achieve enhanced protein degradation. The nanodevice is constructed by encapsulating the commercial BRD4-targeting PROTACs (dBET6) in the hollow cavity of mesoporous silica-coated upconversion nanoparticles, followed by coating a Rose Bengal (RB) photosensitizer conjugated poly-L-lysine (PLL-RB). This composition enables NIR light-activatable generation of cytotoxic reactive oxygen species due to the energy transfer from the UCNPs to PLL-RB, which boosts the endo/lysosomal escape and subsequent cytosolic release of dBET6. We demonstrate that USDPR is capable of effectively degrading BRD4 in a NIR light-controlled manner. This in combination with NIR light-triggered photodynamic therapy enables an enhanced antitumor effect both in vitro and in vivo. This work thus presents a versatile strategy for controlled release of PROTACs and codelivery with photosensitizers using an NIR-responsive nanodevice, providing important insight into the design of effective PROTAC-based combination therapy.

Recent Advances of Photoactive Near-Infrared Carbon Dots in Cancer Photodynamic Therapy

Photodynamic therapy (PDT) is a treatment that employs exogenously produced reactive oxygen species (ROS) to kill cancer cells. ROS are generated from the interaction of excited-state photosensitizers (PSs) or photosensitizing agents with molecular oxygen. Novel PSs with high ROS generation efficiency is essential and highly required for cancer photodynamic therapy. Carbon dots (CDs), the rising star of carbon-based nanomaterial family, have shown great potential in cancer PDT benefiting from their excellent photoactivity, luminescence properties, low price, and biocompatibility. In recent years, photoactive near-infrared CDs (PNCDs) have attracted increasing interest in this field due to their deep therapeutic tissue penetration, superior imaging performance, excellent photoactivity, and photostability. In this review, we review recent progress in the designs, fabrication, and applications of PNCDs in cancer PDT. We also provide insights of future directions in accelerating the clinical progress of PNCDs.

Mitochondrion, lysosome, and endoplasmic reticulum: Which is the best target for phototherapy?

Photodynamic therapy (PDT) is a robust cancer treatment modality, and the precise spatiotemporal control of its subcellular action site is crucial for its effectiveness. However, accurate comparison of the efficacy of different organelle-targeted PDT approaches is challenging since it is difficult to find a single system that can achieve separate targeting of different organelles with separable time windows and similar binding amounts. Herein, we conjugated chlorin e6 (Ce6) with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-5000] (ammonium salt) (DSPE-PEG₅₀₀₀-NH₂) to afford DSPE-PEG-Ce6, which could migrate from mitochondrion to lysosome and ultimately to endoplasmic reticulum (ER) after cellular internalization. Benefiting from the dynamic subcellular distribution of DSPE-PEG-Ce6 with tunable organelle-binding amounts, we accurately determined the PDT efficacy order of the molecule, i.e., mitochondrion > ER > lysosome. This work proposes an ideal model system for accurately evaluating the specific organelle-targeted PDT efficacy and may promote the future development of effective PDT strategies.

Upregulation of MHC-I and downregulation of PD-L1 expression by doxorubicin and deferasirox codelivered liposomal nanoparticles for chemoimmunotherapy of melanoma

Tumor immunotherapy is a promising strategy to activate the immune system and eliminate tumors. Major histocompatibility complex I (MHC-I) is usually applied to potentiate antigen presentation, but it is associated with upregulation of programmed death ligand 1 (PD-L1) expression, which is unfavorable for activation of immune responses. Moreover, poor permeability of various therapeutic antibodies results in the limited immune response rates of most patients. It is necessary to develop combined small molecule drug delivery systems for simultaneous upregulation of MHC-I expression and downregulation of PD-L1 expression, promoting effective tumor treatment. A moderate dose of doxorubicin hydrochloride (DOX) can induce upregulation of MHC-I expression, while deferasirox (DFX) can inhibit the PI3K-Akt pathway, which potentially downregulates PD-L1 expression. In the present study, we designed a pH-sensitive liposome to incorporate DOX in the hydrophilic cavity and embed DFX in the hydrophobic shell, forming a dual delivery system (_DOX-DFXL). In a B16F10 melanoma-bearing mouse model, DOX and DFX were released in acidic tumor microenvironment, which further lead to enhanced antigen presentation and infiltration of T cells into tumor tissues as a result of tumor remission. This codelivery system holds great potential for clinical applications of tumor immunotherapy.

Folic acid functionalized aggregation-induced emission nanoparticles for tumor cell targeted imaging and photodynamic therapy

Recently, molecules with aggregation-induced luminescence (AIE) characteristics have received more and more attention due to the fluorescence of traditional dyes being easily quenched in the aggregated state. AIE molecules have significant advantages, such as excellent light stability, bright fluorescence, high contrast, and large Stokes shift. These characteristics have aroused wide interest of researchers and opened up new applications in many fields, especially in the field of biological applications. However, AIE molecules or their aggregates have certain limitations in multifunctional biological research due to their low specific targeting ability, poor biocompatibility, and poor stability in physiological body fluids. In order to overcome these problems, a novel nanoparticle, FFM1, was fabricated and characterized. FFM1 displayed good water solubility, biocompatibility, and AIE emission properties. It could target HeLa cells specifically by recognizing their folate receptor. Reactive oxygen triggered by light irradiation induced tumor cell apoptosis. Summarily, FFM1 displayed excellent capacity in target imaging and photodynamic killing of HeLa cells. It has shown potential application value in targeted diagnosis and photodynamic therapy of tumors, and has important guiding significance for the treatment of malignant tumors. It paves a way for the development of a novel strategy for tumor theranostics.