Simple Peptide-Tuned Self-Assembly of Photosensitizers towards Anticancer Photodynamic Therapy

Versatile Peptide-Based Nanosystems for Photodynamic Therapy

Photodynamic therapy (PDT) has become an important therapeutic strategy because it is highly controllable, effective, and does not cause drug resistance. Moreover, precise delivery of photosensitizers to tumor lesions can greatly reduce the amount of drug administered and optimize therapeutic outcomes. As alternatives to protein antibodies, peptides have been applied as useful targeting ligands for targeted biomedical imaging, drug delivery and PDT. In addition, other functionalities of peptides such as stimuli responsiveness, self-assembly, and therapeutic activity can be integrated with photosensitizers to yield versatile peptide-based nanosystems for PDT. In this article, we start with a brief introduction to PDT and peptide-based nanosystems, followed by more detailed descriptions about the structure, property, and architecture of peptides as background information. Finally, the most recent advances in peptide-based nanosystems for PDT are emphasized and summarized according to the functionalities of peptide in the system to reveal the design and development principle in different therapeutic circumstances. We hope this review could provide useful insights and valuable reference for the development of peptide-based nanosystems for PDT.

Fmoc-diphenylalanine gelating nanoarchitectonics: A simplistic peptide self-assembly to meet complex applications

9-fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF), has been has been extensively explored due to its ultrafast self-assembly kinetics, inherent biocompatibility, tunable physicochemical properties, and especially, the capability of forming self-sustained gels under physiological conditions. Consequently, various methodologies to develop Fmoc-FF gels and their corresponding applications in biomedical and industrial fields have been extensively studied. Herein, we systemically summarize the mechanisms underlying Fmoc-FF self-assembly, discuss the preparation methodologies of Fmoc-FF hydrogels, and then deliberate the properties as well as the diverse applications of Fmoc-FF self-assemblies. Finally, the contemporary shortcomings which limit the development of Fmoc-FF self-assembly are raised and the alternative solutions are proposed, along with future research perspectives.

Rational design of a minimum nanoplatform for maximizing therapeutic potency: Three birds with one stone

Therapeutic modalities and drug formulations play a crucial and prominent role in actualizing effective treatment and radical cures of tumors. However, the therapeutic efficiency was severely limited by tumor recurrence and complex multi-step preparation of formulation. Therefore, the exploration of novel nanoparticles via a simple and green synthesis process for conquering traditional obstacles and improving therapeutic efficiency is an appealing, yet remarkably challenging task. Herein, a universal nanoplatform allows all cancerous cell-targeting, acid-responsive, cell imaging, synergistic chemotherapy, and nucleolar targeted phototherapy function was tactfully designed and constructed by using chemotherapeutic agents ursolic acid (UA), sorafenib (SF), and carbon dots (CDs) photosensitizers (PSs). The designed US NPs were formed by self-assembly of UA and SF associated with electrostatic, π-π stacking, and hydrophobic interactions. After hydrogen bonding reaction with CDs, the obtained (denoted as USC NPs) have a relatively uniform size of an average 125.6 nm, which facilitated the favorable accumulation of drugs at the tumor region through a potential enhanced permeability and retention (EPR) effect as compared to their counterpart of free CDs solution. Both in vitro and in vivo studies revealed that the advanced platform commenced synergistic anticancer therapeutic potency, imperceptible systematical toxicity, and remarkable reticence towards drug-resistant cancer cells. Moreover, the CDs PSs possess intrinsic nucleolus-targeting ability. Taken together, this theranostics system can fully play the role of "killing three birds with one stone" in a safe manner, implying a promising direction for exploring treatment strategies for cancer and endowing them with great potential for future translational research and providing a new vision for the advancing of an exceptionally forceful protocol for practical cancer therapy.

High performance carbon dots based prodrug Platform: Image-Guided photodynamic and chemotherapy with On-Demand drug release upon laser irradiation

The design of therapeutic nanoplatforms based on fluorescent carbon dots (CDs) has become a viable strategy because of their aqueous solubility, biocompatibility, and ease of further functionalization. By doping various heteroatoms into pristine CDs structures, we synthesized N-, Cl-, and S-doped CDs (NClS/CDs), as well as Se-, N-, and Cl-doped CDs (NClSe/CDs) with superior optoelectronic properties using rapid and straightforward microwave heating. The quantum efficiencies of these NClS/CDs and NClSe/CDs were enhanced to 30.7 % and 42.9 %, respectively, compared to those of undoped CDs (0.66 %). Owing to their better light absorption properties, NClS/CDs efficiently produced reactive oxygen species (ROS) under 532 nm laser irradiation for photodynamic therapy (PDT). Considering the ROS generation and surface carrier abilities of NClS/CDs, we designed the loading of camptothecin (CPT) drug via a thioketal linker (TL), resulting in h/CDs@CPT nanovesicles (NVs) with a drug-loading efficiency of 46.5 %. Under laser irradiation in an acidic environment, ROS-triggered CPT release was observed, with 50.2 % of CPT released following the breakdown of the ROS-sensitive TL. In vitro cellular studies revealed that h/CDs@CPT NVs possessed minimal cytotoxicity toward HeLa and 4 T1 cancer cells, despite the high clinical efficacy of PDT and ROS-induced chemotherapeutic response under laser treatment. Confocal microscopy of HeLa and 4 T1 cells revealed that h/CDs@CPT NVs produced red-emissive photographs for potential cancer cell detection. Therefore, our study presents an image-guided PDT and chemotherapeutic platform based on h/CDs@CPT NVs, which will be an attractive candidate for future cancer treatment.

Amyloid-Gold Nanoparticle Hybrids for Biocompatible Memristive Devices

Biomolecular materials offer tremendous potential for the development of memristive devices due to their low cost of production, environmental friendliness, and, most notably, biocompatibility. Herein, biocompatible memristive devices based on amyloid-gold nanoparticle hybrids have been investigated. These memristors demonstrate excellent electrical performance, featuring an ultrahigh R_off/R_on ratio (>10⁷), a low switching voltage (<0.8 V), and reliable reproducibility. Additionally, the reversible transition from threshold switching to resistive switching mode was achieved in this work. The arrangement of peptides in amyloid fibrils endows the surface polarity and phenylalanine packing, which provides channels for the migration of Ag ions in the memristors. By modulating voltage pulse signals, the study successfully imitates the synaptic behavior of excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and the transition from short-term plasticity (STP) to long-term plasticity (LTP). More interestingly, Boolean logic standard cells were designed and simulated using the memristive devices. The fundamental and experimental results of this study thus offer insights into the utilization of biomolecular materials for advanced memristive devices.

A copper nanocluster-based multifunctional nanoplatform for augmented chemo/chemodynamic/photodynamic combination therapy of breast cancer

With the development of nano drug delivery system, the treatment mode that can overcome the shortcomings of chemotherapy drugs and integrate combined therapy remains to be explored. Herein, a nano drug system was designed to achieve the combined effect of chemo/chemodynamic/photodynamic therapy on cancer. Specifically, copper clusters (CuNCs) were used as the carrier, hyaluronic acid (HA) and doxorubicin (DOX) were coupled on CuNCs and then and chlorin e6 (Ce6) was introduced to form the self-assembled HA-CuNCs@DC nanoparticles. In this system, the HA-CuNCs@DC was involved in the reaction to the acidic tumor microenvironment (TME)-release of DOX, which could not only inhibit tumor growth through chemotherapy, but enhance the generation of hydrogen peroxide. CuNCs carriers had the properties of Fenton-like activity to realize chemodynamic therapy (CDT) and oxidase-like activity to deplete intracellular glutathione (GSH). Additionally, the chemotherapy drug susceptibility increased owing to the GSH depletion and the outbreak of reactive oxygen species, indicating the enhanced CDT efficacy and amplified chemotherapy efficacy. It was also noteworthy that Ce6 could be activated by 660 nm light to produce abundant singlet oxygen for photodynamic therapy. Overall, our platform demonstrated excellent biosafety and tumor suppression capabilities. This multimodal theranostic strategy provided new insights into cancer therapy.

Tailored Cross-β Assemblies Establish Peptide "Dominos" Structures for Anchoring Undruggable Pharmacophores

β-sheets have the ability to hierarchically stack into assemblies, and much effort has been spent on designing different peptides to regulate their assembly behaviors. Although the progress is remarkable, it remains challenging to manipulate them in a controllable way for achieving both tailored structures and specific functions. In this study, we obtained bola-like peptides using de novo design and combinatorial chemical screening. By regulating the solvent-accessible surface area of the peptide chain, a series of assemblies with different tilt angles and active sites of the β-sheet were obtained, resembling collapsed dominos. The structure-activity relationship of the optimized peptide NQ40 system was established and its ability to target the PD-L1 was demonstrated. This study successfully established the structure-function relationship of β-sheets assemblies and has positive implications on the rational design of peptide assemblies that possess recognition abilities.

Unidirectional diphenylalanine nanotubes for dynamically guiding neurite outgrowth

Neural networks have been culturedin vitroto investigate brain functions and diseases, clinical treatments for brain damage, and device development. However, it remains challenging to form complex neural network structures with desired orientations and connectionsin vitro. Here, we introduce a dynamic strategy by using diphenylalanine (FF) nanotubes for controlling physical patterns on a substrate to regulate neurite-growth orientation in cultivating neural networks. Parallel FF nanotube patterns guide neurons to develop neurites through the unidirectional FF nanotubes while restricting their polarization direction. Subsequently, the FF nanotubes disassemble and the restriction of neurites disappear, and secondary neurite development of the neural network occurs in other direction. Experiments were conducted that use the hippocampal neurons, and the results demonstrated that the cultured neural networks by using the proposed dynamic approach can form a significant cross-connected structure with substantially more lateral neural connections than static substrates. The proposed dynamic approach for neurite outgrowing enables the construction of oriented innervation and cross-connected neural networksin vitroand may explore the way for the bio-fabrication of highly complex structures in tissue engineering.

Developing Novel Fabrication and Optimisation Strategies on Aggregation-Induced Emission Nanoprobe/Polyvinyl Alcohol Hydrogels for Bio-Applications

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0-5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2. In contrast to traditional methods, which are expensive and time-consuming and involve polymerization and post-functionalization to develop FL hyperbranched molecules, our proposed method offers a one-step method to prepare an AIE-HB nanoprobe with excellent FL characteristics. We employed the nanoprobe to fabricate fluorescent injectable bioadhesive gel and a hydrogel microchip based on polyvinyl alcohol (PVA). The addition of borax (50 mM) to the PVA + AIE nanoprobe results in the development of an injectable bioadhesive fluorescent gel with the ability to control AIEgen release for 300 min. When borax concentration increases two times (100 mM), the adhesion stress is more than two times bigger (7.1 mN/mm²) compared to that of gel alone (3.4 mN/mm²). Excellent dimensional stability and cell viability of the fluorescent microchip, along with its enhanced mechanical properties, proposes its potential applications in mechanobiology and understanding the impact of microstructure in cell studies.

Pure drug nano-assemblies: A facile carrier-free nanoplatform for efficient cancer therapy

Nanoparticulate drug delivery systems (Nano-DDSs) have emerged as possible solution to the obstacles of anticancer drug delivery. However, the clinical outcomes and translation are restricted by several drawbacks, such as low drug loading, premature drug leakage and carrier-related toxicity. Recently, pure drug nano-assemblies (PDNAs), fabricated by the self-assembly or co-assembly of pure drug molecules, have attracted considerable attention. Their facile and reproducible preparation technique helps to remove the bottleneck of nanomedicines including quality control, scale-up production and clinical translation. Acting as both carriers and cargos, the carrier-free PDNAs have an ultra-high or even 100% drug loading. In addition, combination therapies based on PDNAs could possibly address the most intractable problems in cancer treatment, such as tumor metastasis and drug resistance. In the present review, the latest development of PDNAs for cancer treatment is overviewed. First, PDNAs are classified according to the composition of drug molecules, and the assembly mechanisms are discussed. Furthermore, the co-delivery of PDNAs for combination therapies is summarized, with special focus on the improvement of therapeutic outcomes. Finally, future prospects and challenges of PDNAs for efficient cancer therapy are spotlighted.

Erythrocyte membrane bioengineered nanoprobes via indocyanine green-directed assembly for single NIR laser-induced efficient photodynamic/photothermal theranostics

Traditional combinational photodynamic therapy (PDT) and photothermal therapy (PTT) were limited in clinical therapy of cancer due to exceptionally low drug payload and activation by light with separate wavelengths. We have accidentally discovered that zinc phthalocyanine (ZNPC, a typical hydrophobic photosensitizer) and indocyanine green (ICG, a clinically approved fluorescence probe) could be co-assembled into carrier-free nanodrugs (almost 100 wt%) for single NIR laser-induced efficient PDT/PTT. Interestingly, ICG could act as "transformers" for modulating the geometric shape of ZNPC/ICG co-assembling structures from needle-like/spindle-like structure via cubic structure finally to spherical structure. Unfortunately, the nanodrugs suffered from rapid immune clearance. The ZNPC-ICG nanoprobes were further embedded into the erythrocyte membrane (RBC)-camouflaged framework. The designed ZNPC-ICG@RBC could be efficiently accumulated within the tumor sites (continue for ~60 h) and rapidly internalized into cancer cells upon laser irradiation rather than macrophage RAW264.7 cells. Compared with the free ZnPC or ICG, the biomimetic ZNPC-ICG@RBC nanoprobes exhibited amplified therapeutic effects by simultaneously producing ROS and hyperthermia, thereby synergistically improving antitumor efficiency and eliminating the tumors without any regrowth under the guidance of fluorescence imaging. The co-delivery of ZnPC and ICG via a biomimetic carrier-free system might be a promising strategy for bimodal phototherapy of cancer.

Recent Progress in the Design and Medical Application of In Situ Self-Assembled Polypeptide Materials

Inspired by molecular self-assembly, which is ubiquitous in natural environments and biological systems, self-assembled peptides have become a research hotspot in the biomedical field due to their inherent biocompatibility and biodegradability, properties that are afforded by the amide linkages forming the peptide backbone. This review summarizes the biological advantages, principles, and design strategies of self-assembled polypeptide systems. We then focus on the latest advances in in situ self-assembly of polypeptides in medical applications, such as oncotherapy, materials science, regenerative medicine, and drug delivery, and then briefly discuss their potential challenges in clinical treatment.

Self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics for magnetic resonance/photoacoustic/fluorescence imaging-guided synergistic photo-chemotherapy

Carrier-free nanotheranostics directly assembled by using clinically used photosensitizers and chemotherapeutic drugs are a promising alternative to tumor theranostics. However, the weak interaction-driven assembly still suffers from low structural stability against disintegration, lack of targeting specificity, and poor stimulus-responsive property. Moreover, almost all exogenous ligands possess no therapeutic effect. Enlightened by the concept of metal-organic frameworks, we developed a novel self-recognizing metal-coordinated nanotheranostic agent by the coordination-driven co-assembly of photosensitizer indocyanine green (ICG) and chemo-drug methotrexate (MTX, also served as a specific "targeting ligand" towards folate receptors), in which ferric (FeIII) ions acted as a bridge to tightly associate ICG with MTX. Such carrier-free metal-coordinated nanotheranostics with high dual-drug payload (∼94 wt%) not only possessed excellent structural and physiological stability, but also exhibited prolonged blood circulation. In addition, the nanotheranostics could achieve the targeted on-demand drug release by both stimuli of internal lysosomal acidity and external near-infrared laser. More importantly, the nanotheranostics could self-recognize the cancer cells and selectively target the tumors, and therefore they decreased toxicity to normal tissues and organs. Consequently, the nanotheranostics showed strongly synergistic potency for tumor photo-chemotherapy under the precise guidance of magnetic resonance/photoacoustic/fluorescence imaging, thereby achieving highly effective tumor curing efficiency. Considering that ICG and bi-functional MTX are approved by the Food and Drug Administration, and FeIII ions have high biosafety, the self-recognizing and stimulus-responsive carrier-free metal-coordinated nanotheranostics may hold potential applications in tumor theranostics.

Exploring the self-assembly mechanism and effective synergistic antitumor chemophototherapy of a biodegradable and glutathione responsive ursolic acid prodrug mediated photosensitive nanodrug

Supermolecularly assembled photochemotherapeutic nanocomposites composed of pure drug small molecules are promising for synergistically improved tumor therapy, yet potential multiple challenges remain to be addressed. Herein, we rationally designed a novel multifunctional small molecule disulfide modified natural pentacyclic triterpene of ursolic acid (UASS) that simultaneously possesses self-assembly ability, glutathione (GSH) responsivity, anticancer activity, biocompatibility and biodegradability and further constructed carrier-free GSH-sensitive photosensitive nanocomposite UASS-Ce6 NPs for safe and synergistically improved chemophototherapy. Specifically, UASS-Ce6 NPs exhibit improved 1O2 generation by reducing the energy gap (ΔEST) of Ce6 as determined by density functional theory. Meanwhile, molecular dynamics simulation revealed the possible reasons why free UASS self-assembles and UASS-Ce6 NPs with different assembled morphologies may be primarily attributed to the coplanar arrangement of UASS dimer units. Importantly, via noncovalent π-stacking and hydrophobic interactions, the resulting co-assemblies showed improved water solubility, increased intercellular ROS generation, desirable GSH sensibility, excellent biocompatibility, and enhanced tumor accumulation accompanied by rapid biodegradation, thus leading to significant in vitro and in vivo synergistic antitumor efficacy with favorable biosafety. This study provides a promising insight into the development of a self-assembled active single component platform with desirable stimuli responsiveness and biosafety toward synergistic antitumor therapy based on terpenoid natural small molecules.

Acid-Activatable Transmorphic Peptide-Based Nanomaterials for Photodynamic Therapy

Inspired by the dynamic morphology control of molecular assemblies in biological systems, we have developed pH-responsive transformable peptide-based nanoparticles for photodynamic therapy (PDT) with prolonged tumor retention times. The self-assembled peptide-porphyrin nanoparticles transformed into nanofibers when exposed to the acidic tumor microenvironment, which was mainly driven by enhanced intermolecular hydrogen bond formation between the protonated molecules. The nanoparticle transformation into fibrils improved their singlet oxygen generation ability and enabled high accumulation and long-term retention at tumor sites. Strong fluorescent signals of these nanomaterials were detected in tumor tissue up to 7 days after administration. Moreover, the peptide assemblies exhibited excellent anti-tumor efficacy via PDT in vivo. This in situ fibrillar transformation strategy could be utilized to design effective stimuli-responsive biomaterials for long-term imaging and therapy.

Synergistic Anticancer Therapy by Ovalbumin Encapsulation-Enabled Tandem Reactive Oxygen Species Generation

The anticancer efficacy of photodynamic therapy (PDT) is limited due to the hypoxic features of solid tumors. We report synergistic PDT/chemotherapy with integrated tandem Fenton reactions mediated by ovalbumin encapsulation for improved in vivo anticancer therapy via an enhanced reactive oxygen species (ROS) generation mechanism. O2.- produced by the PDT is converted to H2 O2 by superoxide dismutase, followed by the transformation of H2 O2 to the highly toxic . OH via Fenton reactions by Fe2+ originating from the dissolution of co-loaded Fe3 O4 nanoparticles. The PDT process further facilitates the endosomal/lysosomal escape of the active agents and enhances their intracellular delivery to the nucleus-even for drug-resistant cells. Cisplatin generates O2.- in the presence of nicotinamide adenine dinucleotide phosphate oxidase and thereby improves the treatment efficiency by serving as an additional O2.- source for production of . OH radicals. Improved anticancer efficiency is achieved under both hypoxic and normoxic conditions.

A Paclitaxel Prodrug Activatable by Irradiation in a Hypoxic Microenvironment

The innate hypoxic microenvironment of most solid tumors has a major influence on tumor growth, invasiveness, and distant metastasis. Here, a hypoxia-activated self-immolative prodrug of paclitaxel (PTX₂ -Azo) was synthesized and encapsulated by a peptide copolymer decorated with the photosensitizer chlorin e6 (Ce6) to prepare light-boosted PTX nanoparticle (Ce6/PTX₂ -Azo NP). In this nanoparticle, PTX₂ -Azo prevents premature drug leakage and realizes specific release in hypoxic tumor microenvironment and the photosensitizer Ce6 not only efficiently generates singlet oxygen under light irradiation but also acts as a positive amplifier to promote the release of PTX. The combination of photodynamic therapy (PDT) and chemotherapy results in excellent antitumor efficacy, demonstrating the great potential for synergistic cancer therapy.

Self-Assembling Proteins for Design of Anticancer Nanodrugs

Inspired by the diverse protein-based structures and materials in organisms, proteins have been expected as promising biological components for constructing nanomaterials toward various applications. In numerous studies protein-based nanomaterials have been constructed with the merits of abundant bioactivity and good biocompatibility. However, self-assembly of proteins as a dominant approach in constructing anticancer nanodrugs has not been reviewed. Here, we provide a comprehensive account of the role of protein self-assembly in fabrication, regulation, and application of anticancer nanodrugs. The supramolecular strategies, building blocks, and molecular interactions of protein self-assembly as well as the properties, functions, and applications of the resulting nanodrugs are discussed. The applications in chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, gene therapy, and combination therapy are included. Especially, manipulation of molecular interactions for realizing cancer-specific response and cancer theranostics are emphasized. By expounding the impact of molecular interactions on therapeutic activity, rational design of highly efficient protein-based nanodrugs for precision anticancer therapy can be envisioned. Also, the challenges and perspectives in constructing nanodrugs based on protein self-assembly are presented to advance clinical translation of protein-based nanodrugs and next-generation nanomedicine.

Intercalating pyrene with polypeptide as a novel self-assembly nano-carrier for colon cancer suppression in vitro and in vivo

Giving patients right dosage is an essential concept of precision medicine. Most of nanocarriers lack of flexible drug capacity and structural stability to be customized for specific treatment, resulting in low therapeutic efficacy and unexpected side effects. Thus, a growing need emerges for fast and rigorous approaches to develop nanoparticles with properties of adjustable dosage and controllable particle size. Poly-l-Lysine is known for its enhanced bioadhesivity and pH-triggered structural swelling effect, which is utilized as the main agent to activate the multistage drug releasing. Inspired by natural bio-assembly system, we report a simple method to self-assemble Poly-l-Lysine-based nanoparticles via supramolecular recognitions of cross-linked pyrenes, which provides noncovalent force to flexibly encapsulate Doxorubincin and to construct robust nanostructures. Pyrene-modified polypeptide self-assemblies are able to adjust drug payload from 1: 10 to 2:1 (drug: polypeptide) without changing its uniform nano-spherical morphology. This nanostructure remained the as-made morphology even after experiencing the long-term (~ 10 weeks) storage at room temperature. Also, the nanoparticles displayed multi-step drug release behaviours and exhibited great in vitro and in vivo cytotoxicity towards colon cancer cells. The as-mentioned nanoparticles provide a novel perspective to compensate the clinical needs of specific drug feedings and scalable synthesis with advantages of simple-synthesis, size-adaptivity, and morphology reversibility.

A Multiresponsive Nanohybrid to Enhance the Lysosomal Delivery of Oxygen and Photosensitizers

Photodynamic therapy (PDT) is a promising cancer ablation method, but its efficiency is easily affected by several factors, such as the insufficient delivery of photosensitizers, low oxygen levels as well as long distance between singlet oxygen and intended organelles. A multifunctional nanohybrid, named MGAB, consisting of gelatin-coated manganese dioxide and albumin-coated gold nanoclusters, was designed to overcome these issues by improving chlorin e6 (Ce6) delivery and stimulating oxygen production in lysosomes. MGAB were quickly degraded in a high hydrogen peroxide, high protease activity, and low pH microenvironment, which is closely associated with tumor growth. The Ce6-loaded MGAB were picked up by tumor cells through endocytosis, degraded within the lysosomes, and released oxygen and photosensitizers. Upon near-infrared light irradiation, the close proximity of oxygen with photosensitizer within lysosomes enabled the production of cytotoxic singlet oxygen, resulting in more effective PDT.

Spatiotemporally Coupled Photoactivity of Phthalocyanine-Peptide Conjugate Self-Assemblies for Adaptive Tumor Theranostics

Spatiotemporally coupled tumor phototheranostic platforms offer a flexible and precise system that takes the biological interaction between tumors and photoactive agents into consideration for optimizing treatment, which is highly consistent with precision medicine. However, the fabrication of monocomponent-based photoactive agents applicable to multifold imaging techniques and multiple therapies in a facile way remains challenging. In this study, we developed simple phthalocyanine-peptide (PF) conjugate-based monocomponent nanoparticles with spatiotemporally coupled photoactivity for adaptive tumor theranostics. The self-assembled PF nanoparticles possess well-defined spherical nanostructures and excellent colloidal stability along with supramolecular photothermal effects. Importantly, the PF nanoparticles showed switchable photoactivity triggered by their interactions with the cell membrane, which enables an adaptive transformation from photothermal therapy (PTT) and photoacoustic imaging (PAI) to photodynamic therapy (PDT) and corresponding fluorescence imaging (FI). Theranostic modalities are integrated in a spatiotemporally coupled manner, providing a facile, biocompatible and effective route for localized tumor phototherapy. This study offers a flexible and versatile strategy to integrate multiple theranostic modalities into a single component so that it can realize its full potential and thereby amplify its therapeutic efficacy, creating promising opportunities for the design of theranostics and further highlighting their clinical prospects to the diagnosis and treatment of cancers.

PVA reinforced gossypolone and doxorubicin π-π stacking nanoparticles towards tumor targeting and ultralow dose synergistic chemotherapy

To improve the tumor synergistic therapeutic effects of carrier-free dual-drug delivery systems and realize ultralow dose administration, we developed a tumor targeting and high-efficiency synergistic chemotherapy system (HA-Gn@DPGn NPs) based on polyvinyl alcohol (PVA) reinforced gossypolone (Gn) and doxorubicin (DOX) π-π stacking nanoparticles (DPGn NPs), in which PVA filled the gaps between Gn and DOX and bridged Gn and DOX tightly. Hyaluronic acid modifier hyaluronic acid-gossypolone (HA-Gn) was covered on the surface of DPGn NPs to form HA-Gn@DPGn NPs that procured active targeting properties. This system presented a spherical shape with a uniform hydrodynamic size of 87 ± 6.8 nm, a high drug loading of 80.31%, and high stability. FTIR and UV spectra demonstrated that HA-Gn was covered on the surface of the system and showed significant π-π stacking properties. A considerably low combination index of Gn and DOX (0.1862) was determined at an ultra-low dose of DOX under a Gn : DOX ratio of 50 : 1. HA-Gn@DPGn NPs also demonstrated excellent tumor synergistic therapeutic efficacy (TIR > 87%) at an ultralow dose of DOX and Gn. This system demonstrates high tumor comprehensive synergistic therapeutic efficacy at an ultralow drug dose with multiple favorable therapeutic characteristics, including negligible side effects, tumor targeting ability and thermal-responsive drug release, and thus has considerable potential for tumor synergistic therapy.

Rejuvenated Photodynamic Therapy for Bacterial Infections

The emergence of multidrug resistant bacterial strains has hastened the exploration of advanced microbicides and antibacterial techniques. Photodynamic antibacterial therapy (PDAT), an old-fashioned technique, has been rejuvenated to combat "superbugs" and biofilm-associated infections owing to its excellent characteristics of noninvasiveness and broad antibacterial spectrum. More importantly, bacteria are less likely to produce drug resistance to PDAT because it does not require specific targeting interaction between photosensitizers (PSs) and bacteria. This review mainly focuses on recent developments and future prospects of PDAT. The mechanisms of PDAT against bacteria and biofilms are briefly introduced. In addition to classical macrocyclic PSs, several innovative PSs, including non-self-quenching PSs, conjugated polymer-based PSs, and nano-PSs, are summarized in detail. Numerous multifunctional PDAT systems such as in situ light-activated PDAT, stimuli-responsive PDAT, oxygen self-enriching enhanced PDAT, and PDAT-based multimodal therapy are highlighted to overcome the inherent defects of PDAT in vivo (e.g., limited penetration depth of light and hypoxic environment of infectious sites).

A lanthanide-peptide-derived bacterium-like nanotheranostic with high tumor-targeting, -imaging and -killing properties

Nanostructures formed with bioactive peptides offer an exciting prospect in clinical oncology as a novel class of therapeutic agents for human cancers. Despite their therapeutic potential, however, peptide-based nanomedicines are often inefficacious in vivo due to low cargo-loading efficiency, poor tumor cell-targeting specificity and limited drug accumulation in tumor tissues. Here, we describe the design, via assembly of a p53-activating peptide termed PMI, functionalized PEG and fluorescent lanthanide oxyfluoride nanocrystals, of a novel nanotheranostic shaped in flexible rods. This lanthanide-peptide nanorod or LProd of bionic nature exhibited significantly enhanced tumor-targeting and -imaging properties compared to its spherical counterpart. Importantly, LProd potently inhibited tumor growth in a mouse model of human colon cancer through activating tumor suppressor protein p53 via MDM2/MDMX antagonism, while maintaining a highly favorable biosafety profile. Our data demonstrate that LProd as a multifunctional theranostic platform is ideally suited for tumor-specific peptide drug delivery with real-time disease tracking, thereby broadly impacting clinical development of antitumor peptides.

Hydroxyethyl Starch-Based Nanoparticles Featured with Redox-Sensitivity and Chemo-Photothermal Therapy for Synergized Tumor Eradication

Chemo-photothermal combination therapy could achieve synergistically enhanced efficiency against tumors. Nanocarriers with good safety and high efficiency for chemo- photothermal therapy are pressingly needed. A new type of hydroxyethyl starch (HES) based on nanoparticles (NPs) loaded with doxorubicin (DOX) and indocyanine green (ICG) was, thus, developed in this study. DOX-loaded HES conjugates with redox-sensitivity (HES-SS-DOX) were first synthesized and they were then combined with ICG to self-assemble into HES-SS-DOX@ICG NPs with controlled compositions and sizes via collaborative interactions. The optimal HES-SS-DOX@ICG NPs had good physical and photothermal stability in aqueous media and showed high photothermal efficiency in vivo. They were able to fast release the loaded DOX in response to the redox stimulus and the applied laser irradiation. Based on the H22-tumor-bearing mouse model, these NPs were found to tendentiously accumulate inside tumors in comparison to other major organs. The HES-SS-DOX@ICG NPs together with dose-designated laser irradiation were able to fully eradicate tumors with only one injection and one single subsequent laser irradiation on the tumor site during a 14-day treatment period. In addition, they showed almost no impairment to the body. The presently developed HES-SS-DOX@ICG NPs have good in vivo safety and highly efficient anti-tumor capability. These NPs in conjugation with laser irradiation have promising potential for chemo-photothermal cancer therapy in the clinic.

Aggregation-induced emission (AIE)-active molecules bearing singlet oxygen generation activities: the tunable singlet–triplet energy gap matters

Two-photon active photosensitizers showed relatively strong intersystem crossing facilitating ¹O₂ generation and cell apoptosis with near-infrared excitation.

Peroxisome-targeted Supramolecular Nanoprobes Assembled with Pyrene-labelled Peptide Amphiphiles

Despite the versatile metabolic functions of peroxisomes such as lipid synthesis and fatty acid oxidation and their relevance to genetically inherited diseases, namely, peroxisome biogenesis disorders and peroxisomal enzyme deficiency, there is not much research on peroxisome-targeting therapeutics. Herein we present supramolecular nanostructured probes based on the self-assembly of peptide amphiphiles (PAs) having peroxisome-targeting ability in mammalian cells. The PA was designed to include the peroxisome-targeting tripeptide (SKL) and a fluorescent dye (pyrene). It was revealed that the presence of the SKL-appended carboxyl terminal group of PA, the extent of α-helical nature of the peptide block, and the fibrillar morphology of nano-assemblies affected the targeting efficiency of PA supramolecular nanoprobe. The simple modification of PAs by the peroxisome-targeting strength prediction showed an enhanced peroxisome specificity, as expected. This work provides important insights into designing subcellular organelle-targeting nanoparticles for next-generation nanomedicines.