Tumor acidity-activatable TAT targeted nanomedicine for enlarged fluorescence/magnetic resonance imaging-guided photodynamic therapy

AIEgens Cross-linked Iron Oxide Nanoparticles Synchronously Amplify Bimodal Imaging Signals in Situ by Tumor Acidity-Mediated Click Reaction

Activatable dual-modal molecular imaging probes present a promising tool for the diagnosis of malignant tumors. However, synchronously enhancing dual-modal imaging signals under a single stimulus is challenging. Herein, we propose an activatable bimodal probe that integrates aggregation-induced emission luminogens (AIEgens) and iron oxide nanoparticles (IOs) to synergistically enhance near-infrared fluorescence (NIRF) intensity and magnetic resonance (MR) contrast through a tumor acidity-mediated click reaction. Tumor acidity-responsive IOs containing dibenzocyclooctyne groups (termed cDIOs) and AIEgens containing azide groups (termed AATs) can be covalently cross-linked in response to tumor acidity, which leads to a simultaneous enhancement in NIRF intensity (≈12.4-fold) and r2 relaxivity (≈2.8-fold). cDIOs and AATs were effectively activated in mice orthotropic breast tumor, and the cross-linking prolonged their retention in tumor, further augmenting the bimodal signals and expanding imaging time frame. This facile strategy leverages the inherent properties of probes themselves and demonstrates promise in future translational studies.

An AIE-active bacterial inhibitor and photosensitizer for selective imaging, killing, and photodynamic inactivation of bacteria over mammalian cells

Photodynamic therapy is becoming increasingly popular for combat of bacteria. In the clinical photodynamic combat of bacteria, one critical issue is to avoid the potential damage to the host since the reactive oxygen species produced by photosensitizers are also harmful to mammalian cells. In this work, we report an aggregation-induced-emission-active bacterial inhibitor and photosensitizer, OEO-TPE-MEM (OTM), for the imaging, killing, and light-enhanced inactivation of bacteria. OTM could efficiently bind to and kill Gram-positive bacteria, while its affinity to Gram-negative bacteria is lower, and a higher OTM concentration is required for killing Gram-negative bacteria. OTM is also an efficient photosensitizer and could efficiently sensitize the production of reactive oxygen species, which enhances its killing effect on both Gram-positive and Gram-negative bacteria. More interestingly, OTM is very biocompatible with normal mammalian cells both in the dark and under light irradiation. OTM in mice models with bacteria-infected wounds could promote the healing of infected wounds without affecting their organs and blood parameters, which makes it an excellent candidate for clinical applications.

Application of tumor pH/hypoxia-responsive nanoparticles for combined photodynamic therapy and hypoxia-activated chemotherapy

Introduction: Cancer selectivity, including targeted internalization and accelerated drug release in tumor cells, remains a major challenge for designing novel stimuli-responsive nanocarriers to promote therapeutic efficacy. The hypoxic microenvironment created by photodynamic therapy (PDT) is believed to play a critical role in chemoresistance. Methods: We construct dual-responsive carriers (^DANP_CT) that encapsulate the photosensitizer chlorin e6 (Ce6) and hypoxia-activated prodrug tirapazamine (TPZ) to enable efficient PDT and PDT-boosted hypoxia-activated chemotherapy. Results and discussion: Due to TAT masking, ^DANP_CT prolonged payload circulation in the bloodstream, and selective tumor cell uptake occurred via acidity-triggered TAT presentation. PDT was performed with a spatially controlled 660-nm laser to enable precise cell killing and exacerbate hypoxia. Hypoxia-responsive conversion of the hydrophobic NI moiety led to the disassembly of ^DANP_CT, facilitating TPZ release. TPZ was reduced to cytotoxic radicals under hypoxic conditions, contributing to the chemotherapeutic cascade. This work offers a sophisticated strategy for programmed chemo-PDT.

Functionalization of and through Melanin: Strategies and Bio-Applications

A unique feature of nanoparticles for bio-application is the ease of achieving multi-functionality through covalent and non-covalent functionalization. In this way, multiple therapeutic actions, including chemical, photothermal and photodynamic activity, can be combined with different bio-imaging modalities, such as magnetic resonance, photoacoustic, and fluorescence imaging, in a theragnostic approach. In this context, melanin-related nanomaterials possess unique features since they are intrinsically biocompatible and, due to their optical and electronic properties, are themselves very efficient photothermal agents, efficient antioxidants, and photoacoustic contrast agents. Moreover, these materials present a unique versatility of functionalization, which makes them ideal for the design of multifunctional platforms for nanomedicine integrating new functions such as drug delivery and controlled release, gene therapy, or contrast ability in magnetic resonance and fluorescence imaging. In this review, the most relevant and recent examples of melanin-based multi-functionalized nanosystems are discussed, highlighting the different methods of functionalization and, in particular, distinguishing pre-functionalization and post-functionalization. In the meantime, the properties of melanin coatings employable for the functionalization of a variety of material substrates are also briefly introduced, especially in order to explain the origin of the versatility of melanin functionalization. In the final part, the most relevant critical issues related to melanin functionalization that may arise during the design of multifunctional melanin-like nanoplatforms for nanomedicine and bio-application are listed and discussed.

The Advances and Biomedical Applications of Imageable Nanomaterials

Nanomedicine shows great potential in screening, diagnosing and treating diseases. However, given the limitations of current technology, detection of some smaller lesions and drugs’ dynamic monitoring still need to be improved. With the advancement of nanotechnology, researchers have produced various nanomaterials with imaging capabilities which have shown great potential in biomedical research. Here, we summarized the researches based on the characteristics of imageable nanomaterials, highlighted the advantages and biomedical applications of imageable nanomaterials in the diagnosis and treatment of diseases, and discussed current challenges and prospects.

Multifunctional Nanosystems with Enhanced Cellular Uptake for Tumor Therapy

Rapid development of nanotechnology provides promising strategies in biomedicine, especially in tumor therapy. In particular, the cellular uptake of nanosystems is not only a basic premise to realize various biomedical applications, but also a fatal factor for determining the final therapeutic effect. Thus, a systematic and comprehensive summary is necessary to overview the recent research progress on the improvement of nanosystem cellular uptake for cancer treatment. According to the process of nanosystems entering the body, they can be classified into three categories. The first segment is to enhance the accumulation and permeation of nanosystems to tumor cells through extracellular microenvironment stimulation. The second segment is to improve cellular internalization from extracellular to intracellular via active targeting. The third segment is to enhance the intracellular retention of therapeutics by subcellular localization. The major factors in the delivery can be utilized to develop multifunctional nanosystems for strengthening the tumor therapy. Ultimately, the key challenges and prospective in the emerging research frontier are thoroughly outlined. This review is expected to provide inspiring ideas, promising strategies and potential pathways for developing advanced anticancer nanosystems in clinical practice.

Internally Responsive Nanomaterials for Activatable Multimodal Imaging of Cancer

Advances in technology and nanomedicine have led to the development of nanoparticles that can be activated for multimodal imaging of cancer, where a stimulus induces a material modification that enhances image contrast. Multimodal imaging using nanomaterials with this capability can combine the advantages and overcome the limitations of any single imaging modality. When designed with stimuli-responsive abilities, the target-to-background ratio of multimodal imaging nanoprobes increases because specific stimuli in the tumor enhance the signal. Several aspects of the tumor microenvironment can be exploited as an internal stimulus response for multimodal imaging applications, such as the pH gradient, redox processes, overproduction of various enzymes, or combinations of these. In this review, design strategies are discussed and an overview of the recent developments of internally responsive multimodal nanomaterials is provided. Properly implementing this approach improves noninvasive cancer diagnosis and staging as well as provides a method to monitor drug delivery and treatment response.

Nucleus-Targeted Photosensitizer Nanoparticles for Photothermal and Photodynamic Therapy of Breast Carcinoma

PURPOSE

The near-infrared fluorescent dye indocyanine green (ICG) has shown great potential in the photodynamic therapy (PDT) and photothermal therapy (PTT) of cancer. However, its disadvantages of instability in aqueous solution, short half-life, and non-targeting accumulation limit the effectiveness of ICG PDT/PTT. To overcome the disadvantages of ICG in tumor treatment, we designed PEGylated-human serum albumin (PHSA)-ICG-TAT. In this nanoparticle, PEG4000, the HSA package, and nuclear targeting peptide TAT (human immunodeficiency virus 1 [HIV-1]-transactivator protein) were used to improve the water solubility of ICG, prolong the life span of ICG in vivo, and target the nuclei of tumor cells, respectively.

METHODS

The PHSA-ICG-TAT was characterized in terms of morphology and size, ultraviolet spectrum, dispersion stability, singlet oxygen and cellular uptake, and colocalization using transmission electron microscopy and dynamic light scattering, and fluorescence assay, respectively. Subsequently, the anti-tumor effect of PHSA-ICG-TAT was investigated via in vitro and in vivo experiments, including cell viability, apoptosis, comet assays, histopathology, and inhibition curves.

RESULTS

The designed ICG-loaded nanoparticle had a higher cell uptake rate and stronger PDT/PTT effect than free ICG. The metabolism of PHSA-ICG-TAT in normal mice revealed that there was no perceptible toxicity. In vivo imaging of mice showed that PHSA-ICG-TAT had a good targeting effect on tumors. PHSA-ICG-TAT was used for the phototherapy of tumors, and significantly suppressed the tumor growth. The tumor tissue sections showed that the cell gap and morphology of the tumor tissue had been obviously altered after treatment with PHSA-ICG-TAT.

CONCLUSION

These results indicate that the PHSA-ICG-TAT had a significant therapeutic effect against tumors.

MRI-traceable theranostic nanoparticles for targeted cancer treatment

Current cancer therapies, including chemotherapy and radiotherapy, are imprecise, non-specific, and are often administered at high dosages - resulting in side effects that severely impact the patient's overall well-being. A variety of multifunctional, cancer-targeted nanotheranostic systems that integrate therapy, imaging, and tumor targeting functionalities in a single platform have been developed to overcome the shortcomings of traditional drugs. Among the imaging modalities used, magnetic resonance imaging (MRI) provides high resolution imaging of structures deep within the body and, in combination with other imaging modalities, provides complementary diagnostic information for more accurate identification of tumor characteristics and precise guidance of anti-cancer therapy. This review article presents a comprehensive assessment of nanotheranostic systems that combine MRI-based imaging (T1 MRI, T2 MRI, and multimodal imaging) with therapy (chemo-, thermal-, gene- and combination therapy), connecting a range of topics including hybrid treatment options (e.g. combined chemo-gene therapy), unique MRI-based imaging (e.g. combined T1-T2 imaging, triple and quadruple multimodal imaging), novel targeting strategies (e.g. dual magnetic-active targeting and nanoparticles carrying multiple ligands), and tumor microenvironment-responsive drug release (e.g. redox and pH-responsive nanomaterials). With a special focus on systems that have been tested in vivo, this review is an essential summary of the most advanced developments in this rapidly evolving field.

Recent Progress in the Development of Multifunctional Nanoplatform for Precise Tumor Phototherapy

Phototherapy, including photodynamic therapy and photothermal therapy, mainly relies on phototherapeutic agents (PAs) to produce heat or toxic reactive oxygen species (ROS) to kill tumors. It has attracted wide attention due to its merits of noninvasive properties and negligible drug resistance. However, the phototoxicity of conventional PAs is one of the main challenges for its potential clinical application. This is mainly caused by the uncontrolled distribution of PA in vivo, as well as the inevitable damage to healthy cells along the light path. Ensuring the generation of ROS or heat specific at tumor site is the key for precise tumor phototherapy. In this review, the progress of targeted delivery of PA and activatable phototherapy strategies based on nanocarriers for precise tumor therapy is summarized. The research progress of passive targeting, active targeting, and activatable targeting strategies in the delivery of PA is also described. Then, the switchable nanosystems for tumor precise phototherapy in response to tumor microenvironment, including pH, glutathione (GSH), protein, and nucleic acid, are highlighted. Finally, the challenges and opportunities of nanocarrier-based precise phototherapy are discussed for clinical application in the future.

Intelligent Fe-Mn Layered Double Hydroxides Nanosheets Anchored with Upconversion Nanoparticles for Oxygen-Elevated Synergetic Therapy and Bioimaging

Multimodal synergistic therapy based on photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) has attracted increasing attention in cancer therapy. However, the scant therapeutic efficiency is always a barrier for further application. Herein, a smart tumor microenvironment (TME) responsive nanocatalysts are developed by adopting Fe-Mn layered double hydroxides (FeMn-LDH) as an effective photothermal nanocarrier to load mesoporous silica and chlorin e6 (Ce6)-covalently coated upconversion nanoparticles (UCSP) for multimodal imaging for directed therapy. Under acidic TME, FeMn-LDH degrades into Fe³⁺ and Mn²⁺ ions to initiate a Fenton-like reaction inducing CDT and enhancing magnetic resonance imaging. Additionally, Fe³⁺ can decompose H₂ O₂ to oxygen (O₂ ), enhancing PDT guided by UCSP. As a representative noninvasive imaging probe, the upconversion luminescence will recover after decomposition of FeMn-LDH, and provide high-resolution upconversion luminescent imaging guidance for pinpointed PDT. Moreover, the photothermal properties of FeMn-LDH can further enhance CDT effects. The synergistic therapy and multifunctional imaging can realize the integration of diagnosis and treatment.

Rapid Decomposition and Catalytic Cascade Nanoplatforms Based on Enzymes and Mn-Etched Dendritic Mesoporous Silicon for MRI-Guided Synergistic Therapy

The endogenous tumor microenvironment (TME) can signally influence the therapeutic effects of cancer, so it is necessary to explore effective synergistic therapeutic strategies based on changing of the TME. Here, a catalytic cascade nanoplatform based on manganese (Mn)-etched dendritic mesoporous silicon nanoparticles (designated as DMMnSiO₃ NPs) loaded with indocyanine green (ICG) and natural glucose oxidase (GOD) is established (designated as DIG nanocomposites). As the Mn-O bonds in DMMnSiO₃ NPs are susceptive to mildly acidic and reducing environments, the DIG nanocomposites can be rapidly decomposed because of the biodegradation of DMMnSiO₃ NPs once internalized into the tumor by the consumption of glutathione (GSH) in TME to weaken the antioxidant capability of the tumors. The released Mn²⁺ could catalyze endogenous hydrogen peroxide (H₂O₂) to generate oxygen (O₂) to relieve the hypoxia in TME. The generation of O₂ may promote the catalyzed oxidation of glucose by GOD, which will cut off nutrient supplies, accompanied by the regeneration of H₂O₂. The regenerated H₂O₂ could be sequentially catalyzed by Mn²⁺ to compensate for the consumed O₂, and thus, the catalytic cascade process between Mn²⁺ and GOD was set up. As a result, a synergistic therapeutic strategy based on T₁-weighted magnetic resonance imaging (MRI) of Mn²⁺, starvation therapy by O₂-compensation enhanced catalyzing glucose, dual-model (GSH consumption and O₂ compensation) enhanced photodynamic therapy, and effective photothermal therapy of ICG (η = 23.8%) under 808 nm laser irradiation has been successfully established.

Tumor microenvironment-oriented adaptive nanodrugs based on peptide self-assembly

The aberrant metabolism of tumor cells creates an inimitable microenvironment featuring acidic pH, high glutathione (GSH) levels, and overexpression of certain enzymes, which benefits the overwhelming progress of a tumor. Peptide self-assembly, emerging as a biofriendly and versatile fabrication strategy, harnesses multiple noncovalent interactions to obtain a variety of nanostructures tailored on demand. Orchestrating the reversible nature of noncovalent interactions and abnormal physiological parameters in the tumor microenvironment enables peptide-based nanodrugs to be targetable or switchable, thereby improving the drugs' bioavailability and optimizing the treatment outcome. This review will focus on peptide-modulated self-assembly of photosensitizers, chemotherapeutic drugs, immunoactive agents for tumor microenvironment-oriented adaptive phototherapy, chemotherapy, immunotherapy and combinatorial therapy. We will emphasize the building block design, the intermolecular interaction principle, adaptive structural transformation in the tumor microenvironment and corresponding therapeutic efficacy, and aim to elucidate the critical role of peptide-modulated, tumor microenvironment-oriented adaptive assemblies in improving the therapeutic index. Challenges and opportunities will be covered as well to advance the development and clinical application of tumor therapies based on peptide self-assembly materials and techniques.

Photodynamic Therapy and the Biophysics of the Tumor Microenvironment

Targeting the tumor microenvironment (TME) provides opportunities to modulate tumor physiology, enhance the delivery of therapeutic agents, impact immune response and overcome resistance. Photodynamic therapy (PDT) is a photochemistry-based, nonthermal modality that produces reactive molecular species at the site of light activation and is in the clinic for nononcologic and oncologic applications. The unique mechanisms and exquisite spatiotemporal control inherent to PDT enable selective modulation or destruction of the TME and cancer cells. Mechanical stress plays an important role in tumor growth and survival, with increasing implications for therapy design and drug delivery, but remains understudied in the context of PDT and PDT-based combinations. This review describes pharmacoengineering and bioengineering approaches in PDT to target cellular and noncellular components of the TME, as well as molecular targets on tumor and tumor-associated cells. Particular emphasis is placed on the role of mechanical stress in the context of targeted PDT regimens, and combinations, for primary and metastatic tumors.

Microfluidic Synthesis of Gd-Based Nanoparticles for Fast and Ultralong MRI Signals in the Solid Tumor

Clinically used magnetic resonance imaging contrast agents (MRI CAs) for solid tumors suffer from short life spans and low accumulation at the tumor for their low molecular weights. A good solution is to incorporate these MRI CAs into nanoparticles. Food and Drug Administration-approved compounds, poly(lactic-co-glycolic acid) (PLGA) and lipids, are chosen to assemble these nanoparticles. PLGA/lipid hybrid nanoparticles are assembled in microfluidic channels with a suitable size distribution for imaging tumors. These nanoparticles achieve clearly enhanced MRI contrast at the tumor at 0.5 h postinjection. The enhanced MRI contrast is sustained for 16 h. They can margin the tumor with as good an enhanced MRI contrast as clinical MRI CAs (which visualize the whole tumor) of the solid tumor with much less Gd. They are particularly useful for monitoring the solid tumor after therapy within a day and without repeated administration as clinical MRI CAs.

Cancer-Cell-Activated Photodynamic Therapy Assisted by Cu(II)-Based Metal-Organic Framework

Activation of photosensitizers (PSs) in targeted lesion and minimization of reactive oxygen species (ROS) depletion by endogenous antioxidants constitute promising approaches to perform highly effective image-guided photodynamic therapy (PDT) with minimal non-specific phototoxicity. Traditional strategies to fabricate controllable PS platforms rely on molecular design, which requires specific modification of each PS before PDT. Therefore, construction of a general tumor-responsive PDT platform with minimum ROS loss from endogenous antioxidant, typically glutathione (GSH), is highly desirable. Herein, MOF-199, a Cu(II) carboxylate-based metal-organic framework (MOF), is selected to serve as an inert carrier to load PSs with prohibited photosensitization during delivery. After cellular uptake, Cu (II) in the MOFs effectively scavenges endogenous GSH, concomitantly induces decomposition of MOF-199 to release the encapsulated PSs, and recovers their ROS generation. In vitro and in vivo experiments demonstrate highly effective cancer cell ablation and anticancer PDT with diminished normal cell phototoxicity. This strategy is generally applicable to PSs with both aggregation-induced emission and aggregation-caused quenching to implement activatable and enhanced image-guided PDT.

Multifunctional gene delivery systems with targeting ligand CAGW and charge reversal function for enhanced angiogenesis

A charge reversible polyanion with a targeting peptide was assembled onto binary gene complexes to enhance their endosomal escape and transfection efficiency.

HSA-Coated Magnetic Nanoparticles for MRI-Guided Photodynamic Cancer Therapy

Background: Photodynamic therapy (PDT) is a promising technique for cancer treatment; however, low tissue permeability for irradiating light and insufficient photosensitizer (PS) accumulation in tumors limit its clinical potential. Nanoparticles are engineered to improve selective drug delivery to tumor sites, but its accumulation is highly variable between tumors and patients. Identifying PS accumulation peak in a personalized manner is crucial for therapeutic outcome. Magnetic nanoparticles (MNPs) provide opportunity for tracking drug accumulation in dynamics using non-invasive magnetic resonance imaging (MRI). The purpose of the study was to evaluate MNP loaded with PS as a theranostic tool for treating cancer in mice xenograft colon cancer models. Methods: MNPs coated with human serum albumin (HSA) were loaded with bacteriochlorine a. MRI, atomic emission spectroscopy (AES) and fluorescent imaging were used to study MNP and drug accumulation rates and dynamics in CT26 tumors. Tumor growth curves were evaluated in animals that received PDT at different time points upon MNP systemic injection. Results: Peak MNP accumulation in tumors was detected by MRI 60 min post injection (pi) and the data were verified by AES and fluorescent imaging. Up to 17% of injected dose/g of tissue was delivered to malignant tissues 24 h after injection. Consistent with MRI predicted drug accumulation peak PDT performed 60 min after intravenous injection was more efficient in inhibiting tumor growth than treatment scheduled 30 min and 240 min pi. Conclusions: PS loading on HAS-coated MNPs is a perspective approach to increase drug delivery to tumor site. Tracking for MNP accumulation by MRI can be used to predict drug concentration peak in tumors and to adjust PDT time scheduling for improved antitumor response.

A conveniently synthesized Pt (IV) conjugated alginate nanoparticle with ligand self-shielded property for targeting treatment of hepatic carcinoma

The clinical translation remains a major challenge for platinum drug loaded nanoparticle due to the complexity of composition and preparation. Here we employed only three ingredients to prepare Pt (IV) prodrug-loaded ligand-induced self-assembled nanoparticles (GA-ALG@Pt NPs) via facile one-pot route for liver tumor treatment. GA-ALG@Pt NPs were found equipped with intelligently ligand self-shielded property in which the internal GA could be induced to expose by initial cellular recognition, resulting in strengthened cellular uptake (20%-30%) and prolonged blood circulation time (3.43 times). Appreciable tumor targeting ability (2 times) and especially tumor selectivity (2.5 times) were obtained. Glutathione-triggered release of therapeutic agent generated satisfactory antitumor effect. Bio-safety is also a distinguishing feature of GA-ALG@Pt NPs that greatly relief the nephrotoxicity and systematic toxicity of cisplatin. This conveniently synthesized nanoparticle processes superior targeting capacity and biosecurity, supplying an effective approach to translational cancer therapy in the future.

C-C Chemokine Ligand 2 (CCL2) Recruits Macrophage-Membrane-Camouflaged Hollow Bismuth Selenide Nanoparticles To Facilitate Photothermal Sensitivity and Inhibit Lung Metastasis of Breast Cancer

Poor tumor accumulation, rapid clearance from blood circulation, and high risk of invasive and metastasis are the major barriers that encumber the conventional nanodrug-based tumor therapy. In this work, macrophage membrane (M)-camouflaged quercetin (QE)-loaded hollow bismuth selenide nanoparticles (abbreviated as M@BS-QE NPs) are fabricated for combination therapy of breast cancer. The resulting M@BS-QE NPs are comprehensively characterized, possessing prolonged circulation life, as well as accelerated and enhanced tumoritropic accumulation, compared with those of bare BS NPs because of the immune evading capacity, C-C chemokine ligand 2 (CCL2)-mediated recruitment properties, and active targeting ability. The subsequent QE release under near-infrared (NIR) laser irradiation can selectively sensitize cancer cells to photothermal therapy (PTT) by depleting heat shock protein 70 (HSP70, one malignancy-specific-overexpressed thermoresistance-related chaperone) to realize such a cascaded synergistic effect. At the same time, M@BS-QE NPs down-regulated p-Akt and matrix metalloproteinase-9 (MMP-9, which degrades the extracellular matrix to promote invasion and metastasis of tumors) signal axis to suppress breast cancer lung metastasis. Thus, our results provide a biomimetic strategy, using the characteristics of breast cancer and biological properties of macrophages, that hold great promise to enhance the therapeutic efficacy and improve the accuracy of treatment with minimal side effects on both primary and lung metastasis of breast cancer.

Photodynamic therapy-mediated remote control of chemotherapy toward synergistic anticancer treatment

Stimuli-responsive nanomedicine (NM) with an on-demand drug release property has demonstrated promising utility toward cancer therapy. However, sensitivity and cancer selectivity still remain critical challenges for intelligent NM, which will compromise its therapeutic efficacy and lead to undesired toxicity to normal tissues. Herein, we report a convenient and universal approach to spatiotemporally control the chemodrug release via the photodynamic therapy (PDT)-mediated alteration of the tumor microenvironment. An arylboronic ester (BE)-modified amphiphilic copolymer (mPEG-PBAM) was designed to form micelles and encapsulate doxorubicin (Dox) and hematoporphyrin (Hp). The Dox/Hp co-encapsulated micelles (PB-DH) were stable under normal physiological environment with a uniform size distribution (∼100 nm). In contrast, under tumor-specific light irradiation, extensive reactive oxygen species (ROS) will be generated from Hp in the tumor sites, thus quickly dissociating the micelles and selectively releasing the chemodrug Dox as a consequence of the ROS-mediated cleavage of the hydrophobic BE moieties on the polymers. As such, synergistic anti-cancer efficacy was achieved between the Dox-mediated chemotherapy and the Hp-mediated PDT. This study therefore provides a useful approach to realize the precise and selective control over chemodrug delivery, and it renders promising utilities for the programmable combination of PDT and chemotherapy.

Acetal-Linked Hyperbranched Polyphosphoester Nanocarriers Loaded with Chlorin e6 for pH-Activatable Photodynamic Therapy

Nanocarrier-mediated photodynamic therapy (PDT), which involves the systemic delivery of photosensitizers (PSs) into tumor tissue and tumor cells, has emerged as an attractive treatment for cancer. However, insufficient PS release limits intracellular cytotoxic reactive oxygen species (ROS) generation, which has become a major obstacle to improving the PDT therapeutic efficacy. Herein, a novel hyperbranched polyphosphoester (hbPPE) containing numerous acetal bonds (S-hbPPE/Ce6) was explored as a chlorin e6 (Ce6) nanocarrier for PDT. S-hbPPE/Ce6 with a branched topological structure efficiently encapsulated Ce6 and then significantly enhanced its internalization by tumor cells. Subsequently, the endo-/lysosomal acid microenvironment rapidly cleaved the acetal linkage of S-hbPPE and destroyed the nanostructure of S-hbPPE/Ce6, resulting in increased Ce6 release and obviously elevated the intracellular ROS generation under illumination. Therefore, treatment with S-hbPPE/Ce6 noticeably enhanced the PDT therapeutic efficacy, indicating that such a pH-sensitive hbPPE nanocarrier has great potential to improve the PDT therapeutic efficacy for cancer therapy.

Peptide-based nanoprobes for molecular imaging and disease diagnostics

Pathological changes in a diseased site are often accompanied by abnormal activities of various biomolecules in and around the involved cells. Identifying the location and expression levels of these biomolecules could enable early-stage diagnosis of the related disease, the design of an appropriate treatment strategy, and the accurate assessment of the treatment outcomes. Over the past two decades, a great diversity of peptide-based nanoprobes (PBNs) have been developed, aiming to improve the in vitro and in vivo performances of water-soluble molecular probes through engineering of their primary chemical structures as well as the physicochemical properties of their resultant assemblies. In this review, we introduce strategies and approaches adopted for the identification of functional peptides in the context of molecular imaging and disease diagnostics, and then focus our discussion on the design and construction of PBNs capable of navigating through physiological barriers for targeted delivery and improved specificity and sensitivity in recognizing target biomolecules. We highlight the biological and structural roles that low-molecular-weight peptides play in PBN design and provide our perspectives on the future development of PBNs for clinical translation.

Multiarm Nanoconjugates for Cancer Cell-Targeted Delivery of Photosensitizers

Photodynamic therapy, a procedure that uses a photosensitizer to enable light therapy selectively at diseased sites, remains underutilized in oncological clinic. To further improve its cancer selectivity, we developed a polymeric nanosystem by conjugating a photosensitizer IRDye 700DX (IR700) and cancer targeting RGD peptide to 8-arm polyethylene glycol (PEG). The resulting nanoconjugates (RGD-8PEG-IR700) exhibited a hydrodynamic size of 6.6 nm with narrow distribution of size. The targeted nanoconjugates showed significantly higher intracellular uptake of IR700 in integrin αvβ3-expressing A375 and SKOV3 cells when compared with nontargeted control 8PEG-IR700, and an excess amount of RGD peptides could abolish this enhancement, indicating a receptor-mediated uptake mechanism for the targeted polymer conjugates. Phototoxicity studies indicated that RGD-8PEG-IR700 produced massive cell killing in A375 cells after photoirradiation with an IC₅₀ value of 57.8 nM for IR700. In contrast, free IR700 and the control 8PEG-IR700 conjugates did not produce any phototoxicity at the concentrations up to 1 μM IR700. Upon photoirradiation, the RGD-8PEG-IR700 could produce sufficient singlet oxygen in the cells and induced cell apoptosis. The studies with three-dimensional tumor spheroids showed that they penetrated tumor spheroids deeply and produced strong phototoxicity. Thus, we conclude that the polymer nanoconjugates may provide a promising delivery system for targeted photodynamic therapy of cancers due to their small size, cancer cell specificity, and minimal side effects.

Oligohistidine and targeting peptide functionalized TAT-NLS for enhancing cellular uptake and promoting angiogenesis in vivo

BACKGROUND

Gene therapy has been developed and used in medical treatment for many years, especially for the enhancement of endothelialization and angiogenesis. But slow endosomal escape rate is still one of the major barriers to successful gene delivery. In order to evaluate whether introducing oligohistidine (H_n) sequence into gene carriers can promote endosomal escape and gene transfection or not, we designed and synthesized Arg-Glu-Asp-Val (REDV) peptide functionalized TAT-NLS-H_n (TAT: typical cell-penetrating peptide, NLS: nuclear localization signals, H_n: oligohistidine sequence, n: 4, 8 and 12) peptides with different H_n sequence lengths. pEGFP-ZNF580 (pZNF580) was condensed by these peptides to form gene complexes, which were used to transfect human umbilical vein endothelial cells (HUVECs).

RESULTS

MTT assay showed that the gene complexes exhibited low cytotoxicity for HUVECs. The results of cellular uptake and co-localization ratio demonstrated that the gene complexes prepared from TAT-NLS-H_n with long H_n sequence (n = 12) benefited for high internalization efficiency of pZNF580. In addition, the results of western blot analysis and PCR assay of REDV-TAT-NLS-H₁₂/pZNF580 complexes showed significantly enhanced gene expression at protein and mRNA level. Wound healing assay and transwell migration assay also confirmed the improved proliferation and migration ability of the transfected HUVECs by these complexes. Furthermore, the in vitro and in vivo angiogenesis assay illustrated that these complexes could promote the tube formation ability of HUVECs.

CONCLUSION

The above results indicated that the delivery efficiency of pZNF580 and its expression could be enhanced by introducing H_n sequence into gene carriers. The H_n sequence in REDV-TAT-NLS-H_n is beneficial for high gene transfection. These REDV and H_n functionalized TAT-NLS peptides are promising gene carriers in gene therapy.

Tri-block polymer with interfacial layer formation ability and its use in maintaining supersaturated drug solution after dissolution of solid dispersions

Background

Maintaining a supersaturated drug solution after the dissolution of the solid dispersions of water insoluble drugs continues to be a great challenge and is important to the oral bioavailability enhancement of hardly soluble drugs.

Methods

Nimodipine solid dispersions were prepared by hot-melt extrusion and a special tri-block polymer was employed as a co-carrier. The solid dispersions were characterized by modulated differential scanning calorimetry, transmission electron microscopy, hydrogen-nuclear magnetic resonance and so on.

Results

The tri-block polymer was able to inhibit the formation of drug crystals after dissolution of the solid dispersions. Due to the unique interfacial layer formation ability of the tri-block polymer, a special drug loading micelle which encapsulated the compound and the hydrophobic fragments of the copolymers appeared in the release media. The tri-block polymer was composed of a hydrophilic part forming the shell of micelles, a hydrophobic part shaping the core of micelles, and a special intermediate hydrophilicity part constructing the interfacial layer of micelles.

Conclusion

The tri-block polymer was not only able to stabilize the supersaturated drug solution of solid dispersions to enhance the oral bioavailability of hardly soluble drugs, but is also a potential candidate to construct micelles for systemic administration, due to the good compatibility and organic solvents free micelle formation procedure.

Functional peptide-based nanoparticles for photodynamic therapy

Photodynamic therapy as a non-invasive approach has obtained great research attention during the last decade.

Oxygen Self-Sufficient Amphiphilic Polypeptide Nanoparticles Encapsulating BODIPY for Potential Near Infrared Imaging-guided Photodynamic Therapy at Low Energy

Near infrared (NIR) imaging-guided photodynamic therapy (PDT) is remarkable for its high-efficiency in "see and treat" field. However, hypoxia of cancer cell limits PDT dues to the low singlet oxygen yield. Here MnO₂ conjugated multifunctional polypeptide nanoparticles encapsulating photosensitizer BODIPY has been prepared via a one-step reaction, which can generate oxygen in cancer cytoplasm where rich of H₂O₂, following singlet oxygen by photosensitizer under NIR light irradiation. In vitro studies on HepG2 and 4T1 cancer cells revealed that the as-prepared nanoparticles obviously increase the cell suppression rate under hypoxia conditions, even exposed to an extremely low light energy density (25 mW/cm²). Meanwhile, excellent NIR fluorescence property of BODIPY enabled the nanoparticles to light up the cancer cells for real-time imaging. These results suggest the promises of biocompatible and biodegradable nanoparticles has potential application on efficient NIR imaging-guided photodynamic therapy.

PEG conjugated BODIPY-Br2 as macro-photosensitizer for efficient imaging-guided photodynamic therapy

PEG-BDP macro-photosensitizer was synthesized which showed imaging-guided photodynamic therapy.

Tumor acidity-activatable manganese phosphate nanoplatform for amplification of photodynamic cancer therapy and magnetic resonance imaging

Amorphous biodegradable metal phosphate nanomaterials are considered to possess great potential in cancer theranostic application due to their promise in providing ultra-sensitive pH-responsive therapeutic benefits and diagnostic functions simultaneously. Here we report the synthesis of photosensitising and acriflavine-carrying amorphous porous manganese phosphate (PMP) nanoparticles with ultra-sensitive pH-responsive degradability and their application for a photoactivable synergistic nanosystem that imparts reactive oxygen species (ROS) induced cytotoxicity in synchrony with hypoxia-inducible factor 1α/vascular endothelial growth factor (HIF1α/VEGF) inhibitor that suppresses tumor growth and treatment escape signalling pathway. Carboxymethyl dextran (CMD) is chemically anchored on the surface of porous manganese phosphate theranostic system through the pH-responsive boronate esters. Upon the stimulus of the tumor acid microenvironment, manganese phosphate disintegrates and releases Mn²⁺ ions rapidly, which are responsible for the magnetic resonance imaging (MRI) effect. Meanwhile, the released photosensitizer chlorin e6 (Ce6) produces ROS under irradiation while acriflavine (ACF) inhibits the HIF-1α/VEGF pathway during the burst release of VEGF in tumour induced by photodynamic therapy (PDT), resulting in increased therapeutic efficacy. Considering the strong pH responsivity, MRI signal amplification and drug release profile, the PMP nanoparticles offer new prospects for tumor acidity-activatable theranostic application by amplifying the PDT through inhibiting the HIF-1α /VEGF pathway timely while enhancing the MRI effect.

STATEMENT OF SIGNIFICANCE

In this study, we report the synthesis of the tumor acidity-activatable amorphous porous manganese phosphate nanoparticles and their application for a photoactivable synergistic nanosystem that imparts reactive oxygen species (ROS) induced cytotoxicity in synchrony with hypoxia-inducible factor 1α/vascular endothelial growth factor (HIF-1α/VEGF) inhibitor that suppresses tumor growth and treatment escape signalling pathway. Besides, upon the stimulus of the tumor acid microenvironment, the manganese phosphate nanoparticles finally disintegrate and release Mn²⁺ ions rapidly, which are responsible for the magnetic resonance imaging (MRI) effect. This nanoplatform is featured with distinctive advantages such as ultra pH-responsive drug release, MRI function and rational drug combination exploiting the blockage of the treatment escape signalling pathway.

A Method to Encapsulate Small Organic Molecules in Calcium Phosphate Nanoparticles Based on the Supramolecular Chemistry of Cyclodextrin

Calcium phosphate nanoparticles (CPNPs) encapsulating small organic molecules, such as imaging agents and drugs, are considered to be ideal devices for cancer diagnosis or therapy. However, it is generally difficult to encapsulate small organic molecules in CPNPs because of the lack of solubility in water or binding affinity to calcium phosphate. To solve these issues, we utilized the carboxymethyl β-cyclodextrin (CM-β-CD) to increase the solubility and binding affinity to small organic molecules for the encapsulation into CPNPs in this work. The results indicated that the model molecules, hydrophilic rhodamine B (RB) and hydrophobic docetaxel (Dtxl), are successfully encapsulated into CPNPs with the assistance of CM-β-CD. We also demonstrated the CPNPs could be remarkably internalized into A549 cells, resulting in the efficient inhibition of tumor cells' growth.