Light-Activatable Red Blood Cell Membrane-Camouflaged Dimeric Prodrug Nanoparticles for Synergistic Photodynamic/Chemotherapy

Controllable synthesis of versatile mesoporous organosilica nanoparticles as precision cancer theranostics

Despite the advantages of mesoporous silica nanoparticles (MSNs) in drug delivery, the inherent non-biodegradability seriously impedes the clinical translation of inorganic MSNs, so the current research focus has been turned to mesoporous organosilica nanoparticles (MONs) with higher biocompatibility and easier biodegradability. Recent remarkable advances in silica fabrication chemistry have catalyzed the emergence of a library of MONs with various structures and functions. This review will summarize the latest state-of-the-art studies on the precise control of morphology, structure, framework, particle size and pore size of MONs, which enables the precise synthesis of MONs with suitable engineering for precision stimuli-responsive drug delivery/release, bioimaging and synergistic therapy. Besides, the potential challenges about the future development of MONs are also outlooked with the intention of attracting more researchers to promote the clinical translation of MONs.

Combating the Coronavirus Pandemic: Early Detection, Medical Treatment, and a Concerted Effort by the Global Community

The World Health Organization (WHO) has declared the outbreak of 2019 novel coronavirus, known as 2019-nCoV, a pandemic, as the coronavirus has now infected over 2.6 million people globally and caused more than 185,000 fatalities as of April 23, 2020. Coronavirus disease 2019 (COVID-19) causes a respiratory illness with symptoms such as dry cough, fever, sudden loss of smell, and, in more severe cases, difficulty breathing. To date, there is no specific vaccine or treatment proven effective against this viral disease. Early and accurate diagnosis of COVID-19 is thus critical to curbing its spread and improving health outcomes. Reverse transcription-polymerase chain reaction (RT-PCR) is commonly used to detect the presence of COVID-19. Other techniques, such as recombinase polymerase amplification (RPA), loop-mediated isothermal amplification (LAMP), clustered regularly interspaced short palindromic repeats (CRISPR), and microfluidics, have allowed better disease diagnosis. Here, as part of the effort to expand screening capacity, we review advances and challenges in the rapid detection of COVID-19 by targeting nucleic acids, antigens, or antibodies. We also summarize potential treatments and vaccines against COVID-19 and discuss ongoing clinical trials of interventions to reduce viral progression.

Rational design and latest advances of codelivery systems for cancer therapy

Current treatments have limited effectiveness in treating tumors. The combination of multiple drugs or treatment strategies is widely studied to improve therapeutic effect and reduce adverse effects of cancer therapy. The codelivery system is the key to realize combined therapies. It is necessary to design and construct different codelivery systems in accordance with the variable structures and properties of cargoes and vectors. This review presented the typical design considerations about codelivery vectors for cancer therapy and described the current state of codelivery systems from two aspects: different types of vectors and collaborative treatment strategies. The commonly used loading methods of cargoes into the vectors, including physical and chemical processes, are discussed in detail. Finally, we outline the challenges and perspectives about the improvement of codelivery systems.

Delivery strategies for macromolecular drugs in cancer therapy

With the development of biotherapy, biomacromolecular drugs have gained tremendous attention recently, especially in drug development field due to the sophisticated functions in vivo. Over the past few years, a motley variety of drug delivery strategies have been developed for biomacromolecular drugs to overcome the difficulties in the druggability, e.g., the instability and easily restricted by physiologic barriers. The application of novel delivery systems to deliver biomacromolecular drugs can usually prolong the half-life, increase the bioavailability, or improve patient compliance, which greatly improves the efficacy and potentiality for clinical use of biomacromolecular drugs. In this review, recent studies regarding the drug delivery strategies for macromolecular drugs in cancer therapy are summarized, mainly drawing on the development over the last five years.

NIR light-triggered nanomaterials-based prodrug activation towards cancer therapy

Nanomaterials-based prodrug activation systems have been widely explored in cancer therapy, aiming at overcoming limited dosage formulation, systemic toxicity, and insufficient pharmacokinetic performance of parent drugs. For better delivery control, various stimuli systems, especially nanomaterials-based ones, have come to the forefront. Among them, near-infrared (NIR) light takes advantage of on-demand/site-specific regulation and non-invasiveness. In this review, we will address the developments of nanomaterials-based prodrug over the last decade, the activation mechanisms, and bioapplications under NIR light triggering. The advantages and limitations of NIR-triggered prodrug activation strategies and the perspectives of the next-generation prodrug nanomedicine will also be summarized. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Light-triggered dual-modality drug release of self-assembled prodrug-nanoparticles for synergistic photodynamic and hypoxia-activated therapy

Photodynamic therapy (PDT) leads to tumor hypoxia which could be utilized for the activation of hypoxia-activated prodrugs (HAPs). However, conventional photosensitizer-loaded nanoformulations suffer from an aggregation-caused quenching (ACQ) effect, which limits the efficiency of PDT and synergistic therapy. Herein, prodrug-nanoparticles (NPs) are prepared by the self-assembly of heterodimeric prodrugs composed of pyropheophorbide a (PPa), hypoxia-activated prodrug PR104A, and a thioether or thioketal linkage. In addition, a novel dual-modality drug release pattern is proposed on the basis of the structural states of prodrug-NPs. Under light irradiation, PR104A is released via photoinduced electron transfer (PET) due to the aggregation state of prodrugs. With the disassembly of prodrug-NPs, the ACQ effect is relieved, and PPa produces singlet oxygen which further promotes the reactive oxygen species (ROS)-sensitive release of PR104A. Such prodrug-NPs turn the disadvantage of the ACQ effect to facilitate drug release, demonstrating high-efficiency synergy in combination with PDT and hypoxia-activated therapy.

ROS-Responsive Nanoparticles Formed from RGD-Epothilone B Conjugate for Targeted Cancer Therapy

The targeted nanoagents have shown great potential clinically for cancer therapy. Traditional targeted nanodrugs are usually prepared through surface postmodification. Herein, a nanodrug is self-assembled from the amphiphilic precursor of targeting peptide RGD conjugated with cytotoxin epothilone B (Epo B) through a linker containing the thioketal (tk) group that is sensitive to reactive oxygen species (ROS). The obtained RGD-tk-Epo B conjugate nanoparticles (RECNs) are stable and uniform, which facilitates improving tumor-targeting capacity and accumulation of the drug because of the large number of RGD on the surface of the RECN. After internalization by cancer cells, the blood-inert tk group between RGD and Epo B can be cleaved in the presence of high level of ROS to release Epo B, exhibiting a markedly tumor selectivity and excellent anticancer efficiency in vitro and in vivo.

A RBC membrane-camouflaged biomimetic nanoplatform for enhanced chemo-photothermal therapy of cervical cancer

Due to the untargeted release of chemical drugs, the efficacy of chemotherapy is often compromised along with serious side effects on patients. Recently, the development of targeted delivery systems using nanomaterials as carriers has provided more alternatives for chemical drug transportation. In this study, we developed a novel targeted nanocomplex of GOQD-ICG-DOX@RBCM-FA NPs (GID@RF NPs). First, PEG modified graphene oxide quantum dots (GOQDs) were used to co-load the photosensitizer of indocyanine green (ICG) and DOX, to form GOQD-ICG-DOX NPs (GID NPs). Then, the red blood cell membrane (RBCM) was applied for GID NP camouflage to avoid immune clearance. Finally, folic acid was used to endow the targeting ability of GID@RF NPs. MTT assay showed that the survival rate of HeLa cells reduced by 71% after treatment with GID@RF NPs and laser irradiation. Meanwhile, membrane camouflage significantly prolonged the blood circulation time and enhanced the immune evading ability of GID NPs. Moreover, the drug accumulation at tumor sites was significantly improved through the strong interaction between FA and FA receptor highly expressed on the tumor cells. In vivo assay demonstrated the strongest tumor growth inhibition ability of the combinational chemo/photothermal therapy. H&E analysis indicated no significant abnormalities in the major organs of mice undergoing GID@RF NPs treatment. The level of blood and biochemical parameters remained stable as compared to the control. In summary, this combinational therapy system provides a safe, rapid and effective alternative for the treatment of cervical cancer in the future.

Tailoring nanoparticles based on boron dipyrromethene for cancer imaging and therapy

Boron dipyrromethene (BODIPY), as a traditional fluorescent dye, has drawn increasing attention because of its excellent photophysical properties like adjustable spectra and outstanding photostability. BODIPY dyes could be assembled into nanoparticles for cancer imaging and therapy via rational design. In this review, the bio-applications of BODIPY-containing nanoparticles are introduced in detail, such as cellular imaging, near-infrared fluorescence imaging, computed tomography imaging, photoacoustic imaging, phototherapy, and theranostics. The construction strategies of BODIPY-containing nanoparticles are emphasized so the review has three sections-self-assembly of small molecules, chemical conjugation with hydrophilic compounds, and physical encapsulation. This review not only summarizes various and colorific bio-applications of BODIPY-containing nanoparticles, but also provides reasonable design methods of BODIPY-containing nanoparticles for cancer theranostics. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Size-Tunable Strategies for a Tumor Targeted Drug Delivery System

Nanoparticles have been widely used in tumor targeted drug delivery, while the antitumor effects are not always satisfactory due to the limited penetration and retention. As we all know, there is a paradox that nanoparticles with large sizes tend to distribute around tumor blood vessels rather than penetrate into tumor parenchyma, while smaller sizes can penetrate deeply but with poor tumor retention. In recent days, an intelligent, size-tunable strategy provided a solution to determine the size problem of nanoparticles and exhibited good application prospects. In this review, we summarize series of stimuli-induced aggregation and shrinkage strategies for tumor targeted drug delivery, which can significantly increase the retention and penetration of nanodrugs in tumor sites at the same time, thus promoting treatment efficacy. Internal (enzymes, pH, and redox) and external (light and temperature) stimuli are introduced to change the morphology of the original nanodrugs through protonation, hydrophobization, hydrogen bond, π-π stacking and enzymolysis-resulted click reactions or dissociation, etc. Apart from applications in oncotherapy, size-tunable strategies also have a great prospect in the diagnosis and real time bioimaging fields, which are also introduced in this review. Finally, the potential challenges for application and future directions are thoroughly discussed, providing guidance for further clinical transformation.

Cell membrane-coated nanoparticles: research advances

Cell membranes have been continuously imitated and used for the modification of nanoparticles (NPs) to improve NP biological properties. Cell membrane-coated NPs, where core NPs are wrapped with plasma membrane vesicles, show high biocompatibility, targeting specificity and low side effects. Compared with conventional strategies, this novel approach directly leverages intact and natural functions of cell membranes, instead of replicating these features via synthetic techniques. This top-down technique bestows NPs with enhanced biointerfacing capabilities with potential in the diagnosis and treatment of cancer, infection and other diseases. Herein, we report on the advances in cell membrane-coated NPs, including the preparation process, source cell membranes for wrapping and potential applications of these cell membrane-coated NPs.

Helix Self-Assembly Behavior of Amino Acid-Modified Camptothecin Prodrugs and Its Antitumor Effect

For effective antitumor treatment, it is important to increase the water solubility of hydrophobic antitumor drugs and improve their cell absorption efficiency and nuclear transmission capacity. Here, we use endogenous hydrophilic arginine to modify camptothecin (CPT) to increase its water solubility. Surprisingly, the modified CPT can self-assemble into helical nanofibers through intermolecular π-π stacking and hydrophilic-hydrophobic interactions. Prodrug-based nanofibers were better endocytosed into the nucleus than their nonassembled CPT. Moreover, in vivo, such nanofibers had a longer blood circulation time and a better ability to accumulate in the tumor site. Further, we found that the cationic nanofibers can be combined with the anionic cisplatin-polyglutamic acid through electrostatic interaction to achieve a combined antitumor effect. This provides a new idea for achieving more effective cancer chemotherapy effects.

Tumor cell-derived exosomes home to their cells of origin and can be used as Trojan horses to deliver cancer drugs

Cancer is the second leading cause of death worldwide and patients are in urgent need of therapies that can effectively target cancer with minimal off-target side effects. Exosomes are extracellular nano-shuttles that facilitate intercellular communication between cells and organs. It has been established that tumor-derived exosomes contain a similar protein and lipid composition to that of the cells that secrete them, indicating that exosomes might be uniquely employed as carriers for anti-cancer therapeutics. Methods: We isolated exosomes from two cancer cell lines, then co-cultured each type of cancer cells with these two kinds of exosomes and quantified exosome. HT1080 or Hela exosomes were systemically injected to Nude mice bearing a subcutaneous HT1080 tumor to investigate their cancer-homing behavior. Moreover, cancer cell-derived exosomes were engineered to carry Doxil (a common chemotherapy drug), known as D-exo, were used to detect their target and therapeutic efficacy as anti-cancer drugs. Exosome proteome array analysis were used to reveal the mechanism underly this phenomenon. Results: Exosomes derived from cancer cells fuse preferentially with their parent cancer cells, in vitro. Systemically injected tumor-derived exosomes home to their original tumor tissues. Moreover, compared to Doxil alone, the drug-loaded exosomes showed enhanced therapeutic retention in tumor tissues and eradicated them more effectively in nude mice. Exosome proteome array analysis revealed distinct integrin expression patterns, which might shed light on the underlying mechanisms that explain the exosomal cancer-homing behavior. Conclusion: Here we demonstrate that the exosomes' ability to target the parent cancer is a phenomenon that opens up new ways to devise targeted therapies to deliver anti-tumor drugs.

Paclitaxel-Potentiated Photodynamic Theranostics for Synergistic Tumor Ablation and Precise Anticancer Efficacy Monitoring

Photodynamic theranostics that allows for concurrent photodynamic therapy (PDT) and precise therapeutic response report has emerged as an intriguing direction in the development of precision medicine. An ultra-efficient photodynamic theranostics platform was developed here based on combining and potentiating a theranostic photosensitizer, TPCI, with other therapies for synergistic anticancer effect and synchronous self-reporting of therapeutic response. In this study, TPCI and a chemotherapy agent paclitaxel (PTX) were co-encapsulated in liposomes, which exhibited a superb synergistic anticancer effect against a series of tumor cell lines. The potency of both drugs had been boosted for up to 30-fold compared with sole PDT or chemotherapy. More strikingly, the released TPCI lighted up the nuclei of dead cells, triggered either by PDT or chemotherapy, through binding with the chromatin and activating its aggregation-induced emission, therefore self-reporting the anticancer effect of the combined therapy in real time. The in vivo study using a mouse model bearing PC3 prostate tumor cells demonstrated the effective ablation of tumors with initial sizes of 200 mm³ and the precise early tumor response monitoring by TPCI/PTX@Lipo. This PTX-potentiated photodynamic theranostics strategy herein represented a new prototype of self-reporting nanomedicine for precise tumor therapy.

Cell Membrane-Camouflaged Nanocarriers for Cancer Diagnostic and Therapeutic

Cell membrane (CM)-camouflaged nanocarriers (CMNPs) are the tools of a biomimetic strategy that has attracted significant attention. With a wide range of nanoparticle cores and CMs available, various creative CMNP designs have been studied for cancer diagnosis and therapy. The various functional CM molecules available allow CMNPs to demonstrate excellent properties such as prolonged circulation time, immune escape ability, reduced systemic toxicity, and homologous targeting ability when camouflaged with CMs derived from various types of natural cells including red and white blood cells, platelets, stem cells, and cancer cells. In this review, we summarize various CMNPs employed for cancer chemotherapy, immunotherapy, phototherapy, and in vivo imaging. We also predict future challenges and opportunities for fundamental and clinical studies.

Bright red aggregation-induced emission nanoparticles for multifunctional applications in cancer therapy

Developing multifunctional photosensitizers (PSs) is needed to effectively simplify cancer treatment, but it remains a big challenge. Here, two red-emitting AIE-active, donor-acceptor (D-A) PSs with small ΔE ST and their AIE nanoparticles, are rationally designed and synthesized. The PS1 NPs exhibit bright red-emission with high quantum yield, appropriate 1O2 generation ability and good biocompatibility. More importantly, PS1 NPs can strongly light up the cytoplasm by gently shaking the cells for only 5 s at room temperature, indicating ultrafast staining and mild incubation conditions. In vitro and in vivo cell tracing demonstrate that PS1 NPs can track cells over 14 days, and effectively inhibit tumor growth upon irradiation. To the best of our knowledge, this work is the first example of a PS that integrates image-guided PDT, ultrafast staining and long-term tracing functions, demonstrating the "all-in-one" concept which offers great advantages for potential clinical applications.

A pH-Responsive Charge-Reversal Drug Delivery System with Tumor-Specific Drug Release and ROS Generation for Cancer Therapy

INTRODUCTION

Poor cell uptake and incomplete intracellular drug release are the two major challenges for polymeric prodrug-based drug delivery systems (PPDDSs) in cancer treatment.

METHODS

Herein, a PPDDS with pH-induced surface charge-reversal and reactive oxygen species (ROS) amplification for ROS-triggered self-accelerating drug release was developed, which was formed by encapsulating a ROS generation agent (vitamin K3 (VK3)) in pH/ROS dual-sensitive polymetric prodrug (PEG-b-P(LL-g-TK-PTX)-(LL-g-DMA)) based micelle nanoparticles (denoted as PVD-NPs).

RESULTS

The surface charge of the PVD-NPs can change from negative to positive for enhanced cell uptake in response to tumor extracellular acidity pH. After internalization by cancer cells, PVD-NPs demonstrate dual drug release in response to intracellular ROS-rich conditions. In addition, the released VK3 can produce ROS under the catalysis by NAD(P)H:quinone oxidoreductase-1, which facilitates tumor-specific ROS amplification and drug release selectively in cancer cells to enhance chemotherapy.

CONCLUSION

Both in vitro and in vivo experiments demonstrated that the PVD-NPs showed significant antitumor activity in human prostate cancer.

Cell membrane-engineered hybrid soft nanocomposites for biomedical applications

An overview of various cell membrane-engineered hybrid soft nanocomposites for medical applications.

In vivo therapeutic response monitoring by a self-reporting upconverting covalent organic framework nanoplatform

The real-time and in situ monitoring of reactive oxygen species (ROS) generation is critical for minimizing the nonspecific damage derived from the high doses of ROS required during the photodynamic therapy (PDT) process. However, phototherapeutic agents that can generate ROS-related imaging signals during PDT are rare, hampering the facile prediction of the future therapeutic outcome. Herein, we develop an upconverting covalent organic framework (COF) nanoplatform via a core-mediated strategy and further functionalized it with a singlet oxygen reporter for the efficient near-infrared activated and in situ self-reporting of PDT. In this work, the COF photodynamic efficacy is greatly improved (12.5 times that of irregular COFs) via tailoring the size. Furthermore, this nanoplatform is able to not only produce singlet oxygen for PDT, but it can also emit singlet oxygen-correlated luminescence, allowing the real-time and in situ monitoring of the therapeutic process for cancer cells or solid tumors in vivo via near-infrared luminescence imaging. Thus, our core-mediated synthetic and size-tailored strategy endows the upconverting COF nanoplatform with promising abilities for high-efficacy, deep-tissue, precise photodynamic treatment.

Activatable molecular agents for cancer theranostics

Theranostics that integrates diagnosis and treatment modalities has attracted great attention due to its abilities of personalized therapy and real-time monitoring of therapeutic outcome. Such a theranostic paradigm requires agents to simultaneously possess the capabilities of targeting, imaging, and treatment. Activatable molecular agents (AMAs) are promising for cancer theranostics, as they show a higher signal-to-noise ratio (SNR), real-time detection of cancer-associated biomarkers, lower normal tissue toxicity, and a higher therapeutic effect. This perspective summarizes the recent advancements of AMAs, which include imaging-guided chemotherapy, imaging-guided photodynamic therapy, and imaging-guided photothermal therapy. The molecular design principles, theranostic mechanisms, and biomedical applications of AMAs are described, followed by a discussion of potential challenges of AMAs in cancer theranostics.

Cell Membrane Coating Technology: A Promising Strategy for Biomedical Applications

Cell membrane coating technology is an approach to the biomimetic replication of cell membrane properties, and is an active area of ongoing research readily applicable to nanoscale biomedicine. Nanoparticles (NPs) coated with cell membranes offer an opportunity to unite natural cell membrane properties with those of the artificial inner core material. The coated NPs not only increase their biocompatibility but also achieve effective and extended circulation in vivo, allowing for the execution of targeted functions. Although cell membrane-coated NPs offer clear advantages, much work remains before they can be applied in clinical practice. In this review, we first provide a comprehensive overview of the theory of cell membrane coating technology, followed by a summary of the existing preparation and characterization techniques. Next, we focus on the functions and applications of various cell membrane types. In addition, we collate model drugs used in cell membrane coating technology, and review the patent applications related to this technology from the past 10 years. Finally, we survey future challenges and trends pertaining to this technology in an effort to provide a comprehensive overview of the future development of cell membrane coating technology.

Microfluidic Sonication To Assemble Exosome Membrane-Coated Nanoparticles for Immune Evasion-Mediated Targeting

Using natural membranes to coat nanoparticles (NPs) provides an efficient means to reduce the immune clearance of NPs and improve their tumor-specific targeting. However, fabrication of these drug-loaded biomimetic NPs, such as exosome membrane (EM)- or cancer cell membrane (CCM)-coated poly(lactic-co-glycolic acid) (PLGA) NPs, remains a challenging task owing to the heterogeneous nature of biomembranes and labor-intensive procedures. Herein, we report a microfluidic sonication approach to produce EM-, CCM-, and lipid-coated PLGA NPs encapsulated with imaging agents in a one-step and straightforward manner. Tumor cell-derived EM-coated PLGA NPs consisting of both endosomal and plasma membrane proteins show superior homotypic targeting as compared to CCM-PLGA NPs of similar sizes and core-shell structures in both in vitro and in vivo models. The underlying mechanism is associated with a significantly reduced uptake of EM-PLGA NPs by macrophages and peripheral blood monocytes, revealing an immune evasion-mediated targeting of EM-PLGA NPs to homologous tumors. Overall, this work illustrates the promise of using microfluidic sonication approach to fabricate biomimetic NPs for better biocompatibility and targeting efficacy.

Tumor-Microenvironment-Activatable Nanoreactor Based on a Polyprodrug for Multimodal-Imaging-Medicated Enhanced Cancer Chemo/Phototherapy

Anticancer nanomedicine-based multimodal imaging and synergistic therapy hold great promise in cancer diagnosis and therapy owing to their abilities to improve therapeutic efficiency and reduce unnecessary side effects, producing promising clinical prospects. Herein, we integrated chemotherapeutic drug camptothecin (CPT) and near-infrared-absorbing new indocyanine green (IR820) into a single system by charge interaction and obtained a tumor-microenvironment-activatable PCPT_SS/IR820 nanoreactor to perform thermal/fluorescence/photoacoustic-imaging-guided chemotherapy and photothermal therapy simultaneously. Specifically, the generated PCPT_SS/IR820 showed an excellent therapeutic agent loading content and size stability, and the trials in vitro and in vivo suggested that the smart PCPT_SS/IR820 could deeply permeate into tumor tissues due to its suitable micellar size. Upon near-infrared laser irradiation, the nanoreactor further produced a terrific synergism of chemo-photo treatment for cancer therapy. Therefore, the PCPT_SS/IR820 polyprodrug-based nanoreactor holds outstanding promise for multimodal imaging and combined dual therapy.

Near-infrared light-triggered degradable hyaluronic acid hydrogel for on-demand drug release and combined chemo-photodynamic therapy

In this study, an injectable and near-infrared (NIR) light-triggered ROS-degradable hyaluronic acid hydrogel platform was developed as localized delivery vehicle for photosensitizer protophorphyrin IX (PpIX) and anticancer drug doxorubicin (DOX), to achieve superior combined chemo-photodynamic therapy with light-tunable on-demand drug release. The in situ-forming hydrogel fabricated readily via the formation of dynamic covalent acylhydrazone bonds could efficiently prevent severe self-quenching effect of water-insoluble PpIX due to the covalent binding, leading to localized enhanced photodynamic therapy (PDT). Moreover, the extensive ROS generated by the hydrogel under NIR light irradiation could not only realize efficient PDT effect, but also cleave the ROS-cleavable small molecule crosslinker, inducing the desirable degradation of hydrogel and subsequent on-demand DOX release for cascaded chemotherapy. The developed versatile hyaluronic acid hydrogels have tunable properties, excellent biocompatibility, biodegradability and exhibit outstanding therapeutic effects in both in vitro cellular experiments and in vivo antitumor studies.

Multistep Consolidated Phototherapy Mediated by a NIR-Activated Photosensitizer

The multifunctional effect of a single molecule for therapeutic functionalities on a single theranostic nanosystem has a great significance to enhance the accuracy of diagnosis and improve the efficacy of therapy. Herein, a biocompatible multistep phototherapeutic system (Ppa-Cy7-PEG-biotin) that contains a photosensitizer pyropheophorbide A (Ppa) with the covalent conjunction of a near-infrared (NIR) cyanine dye (Cy7) was successfully fabricated and functionalized with biotin for flexible specific tumor-targeting phototherapy. These theranostic micelles will disaggregate after NIR irradiation via the photodegradation of cyanine accompanied by the photothermal conversion and the optically controlled release for the restoration of photodynamic function of quenched Ppa. Consecutively, promoted treatments of photosensitive molecules greatly prolonged the tumor retention time and treatment efficiency, having a multistep antitumor effect both in vitro and in vivo. Different from the simple phototherapeutic configurations that only act on the superficial areas of tumors at mild doses, the multistep therapy can be competent for broadly damaging the superficial and deeper regions of tumors at the same dose. Therefore, as opposed to the general combination phototherapeutic approach, this strategy presents a photoactivation-based multistep phototheranostic platform with an enormous potential in enhanced combined phototherapy for cancer.

Nanotransducers for Near-Infrared Photoregulation in Biomedicine

Photoregulation, which utilizes light to remotely control biological events, provides a precise way to decipher biology and innovate in medicine; however, its potential is limited by the shallow tissue penetration and/or phototoxicity of ultraviolet (UV)/visible light that are required to match the optical responses of endogenous photosensitive substances. Thereby, biologically friendly near-infrared (NIR) light with improved tissue penetration is desired for photoregulation. Since there are a few endogenous biomolecules absorbing or emitting light in the NIR region, the development of molecular transducers is essential to convert NIR light into the cues for regulation of biological events. In this regard, optical nanomaterials able to convert NIR light into UV/visible light, heat, or free radicals are suitable for this task. Here, the recent developments of optical nanotransducers for NIR-light-mediated photoregulation in medicine are summarized. The emerging applications, including photoregulation of neural activity, gene expression, and visual systems, as well as photochemical tissue bonding, are highlighted, along with the design principles of nanotransducers. Moreover, the current challenges and perspectives in this field are discussed.

Engineering Biomimetic Platesomes for pH-Responsive Drug Delivery and Enhanced Antitumor Activity

Biomimetic camouflage, i.e., using natural cell membranes for drug delivery, has demonstrated advantages over synthetic materials in both pharmacokinetics and biocompatibility, and so represents a promising solution for the development of safe nanomedicine. However, only limited efforts have been dedicated to engineering such camouflage to endow it with optimized or additional properties, in particular properties critical to a "smart" drug delivery system, such as stimuli-responsive drug release. A pH-responsive biomimetic "platesome" for specific drug delivery to tumors and tumor-triggered drug release is described. This platesome nanovehicle is constructed by merging platelet membranes with functionalized synthetic liposomes and exhibits enhanced tumor affinity, due to its platelet membrane-based camouflage, and selectively releases its cargo in response to the acidic microenvironment of lysosomal compartments. In mouse cancer models, it shows significantly better antitumor efficacy than nanoformulations based on a platesome without pH responsiveness or those based on traditional pH-sensitive liposomes. A convenient way to incorporate stimuli-responsive features into biomimetic nanoparticles is described, demonstrating the potential of engineered cell membranes as biomimetic camouflages for a new generation of biocompatible and efficient nanocarriers.

Boron Dipyrromethene Nano-Photosensitizers for Anticancer Phototherapies

As traditional phototherapy agents, boron dipyrromethene (BODIPY) photosensitizers have attracted increasing attention due to their high molar extinction coefficients, high phototherapy efficacy, and excellent photostability. After being formed into nanostructures, BODIPY-containing nano-photosensitizers show enhanced water solubility and biocompatibility as well as efficient tumor accumulation compared to BODIPY molecules. Hence, BODIPY nano-photosensitizers demonstrate a promising potential for fighting cancer. This review contains three sections, classifying photodynamic therapy (PDT), photothermal therapy (PTT), and the combination of PDT and PTT based on BODIPY nano-photosensitizers. It summarizes various BODIPY nano-photosensitizers, which are prepared via different approaches including molecular precipitation, supramolecular interactions, and polymer encapsulation. In each section, the design strategies and working principles of these BODIPY nano-photosensitizers are highlighted. In addition, the detailed in vitro and in vivo applications of these recently developed nano-photosensitizers are discussed together with future challenges in this field, highlighting the potential of these promising nanoagents for new tumor phototherapies.

Dynamically enhancing plaque targeting via a positive feedback loop using multifunctional biomimetic nanoparticles for plaque regression

A paradigm shift from preventive therapy to aggressive plaque regression and eventual eradication is much needed to address increasing atherosclerotic burden and risks. Herein, we report a biologically inspired dual-targeting multifunctional recombinant high-density lipoprotein (rHDL)-mimicking core-shell nanoplatform. It is composed of an ATP-responsive ternary polyplexes core for SR-A siRNA and catalase complexation, and a phosphatidylserine-modified rHDL-based outer shell for SR-BI and CD36 targeting, in which pitavastatin is packaged. We demonstrated that dual-targeting biomimetic core-shell nanoparticles dynamically enhanced macrophage CD36 targeting in the plaques by establishing a positive feedback loop via the reciprocal regulation of SR-A and CD36. Positive feedback-enabled accumulation of the nanoparticles in the atherosclerotic plaques increased by 3.3-fold following 4-week repeated administration. A 3-month dosage regimen of the dual-targeting rHDL-mimicking nanoparticles reduced plaque areas by 65.8%, and decreased macrophages by 57.3%. Collectively, this work shows that dynamically enhancing plaque targeting via a positive feedback loop and dual action of cholesterol deposition inhibition and efflux enhancement accomplished with our novel multifunctional biomimetic nanoparticles provides a new way to regress plaques and alleviate the atherosclerotic burden.

Photodynamic PEG-coated ROS-sensitive prodrug nanoassemblies for core-shell synergistic chemo-photodynamic therapy

The combination of chemotherapy with photodynamic therapy (PDT) holds promising applications in cancer therapy. However, co-encapsulation of chemotherapeutic agents and photosensitizers (PS) into the conventional nanocarriers suffers from inefficient co-loading and aggregation-caused quenching (ACQ) effect of PS trapped in dense carrier materials. Herein, we report a light-activatable photodynamic PEG-coated prodrug nanoplatform for core-shell synergistic chemo-photodynamic therapy. A novel photodynamic polymer is rationally designed and synthesized by conjugating pyropheophorbide a (PPa) to polyethylene glycol 2000 (PEG_2k). PPa is used as the hydrophobic and photodynamic moiety of the amphipathic PPa-PEG_2k polymer. Then, a core-shell nanoassembly is prepared, with an inner core of a reactive oxygen species (ROS)-responsive oleate prodrug of paclitaxel (PTX) and an outer layer of PPa-PEG_2k. PPa-PEG_2k serves for both PEGylation and PDT. Instead of being trapped in the inner core, PPa in the outer PPa-PEG_2k layer significantly alleviates the ACQ effect. Under laser irradiation, ROS generated by PPa-PEG_2k not only is used for PDT but also synergistically promotes PTX release in combination with the endogenous ROS overproduced in tumor cells. The photodynamic PEG-coated nanoassemblies demonstrated synergistic antitumor activity in vivo. Such a unique nanoplatform, with an inner chemotherapeutic core and an outer photodynamic PEG shell, provides a new strategy for synergistic chemo-photodynamic therapy. STATEMENT OF SIGNIFICATION: The combination of chemotherapy with photodynamic therapy (PDT) holds promising prospects in cancer therapy. However, it remains a tremendous challenge to effectively co-deliver chemotherapeutic drugs and photosensitizers into tumors. Herein, we construct a photodynamic PEGylation-coated prodrug-nanoplatform for high-efficiency synergistic cancer therapy, which is composed of a light-activatable PPa-PEG_2k shell and a ROS-responsive paclitaxel (PTX) prodrug core. The PPa-PEG_2k-generated ROS not only was used for synergistic PTX release but also synergistically facilitated tumor cell apoptosis in combination with PTX-initiated chemo-cytotoxicity. The light-activatable nanoassemblies exhibited multiple drug delivery advantages including high co-loading efficiency, self-enhanced PTX release, extended circulation time, favorable biodistribution, and potent synergistic anticancer activity. Our findings provide a new strategy for the rational design of advanced nano-DDS for high-efficiency combinational chemo-photodynamic therapy.

Red blood cells as an efficient in vitro model for evaluating the efficacy of metallic nanoparticles

Blood and the linings of blood vessels may be regarded as a fifth tissue type. The human body contains 5 × 10⁹ red blood cells (RBCs) per ml, a total of 2.5 × 10¹³ cells in the 5 l of blood present in the body. With an average lifetime of 125 days, human RBCs are destroyed by leukocytes in the spleen and liver. Nowadays red blood cells are extensively used to study various metabolic functions. Nanoparticles (NP) are being widely accepted for drug delivery system. This review summarizes the red blood cells, NPs and their characteristics on the basis of the RBC components along with drug delivery systems through RBCs. Further, we also discussed that how erythrocytes can be used as an efficient in vitro model for evaluating the efficacy of various nanocomposite materials.

Sequentially responsive biomimetic nanoparticles with optimal size in combination with checkpoint blockade for cascade synergetic treatment of breast cancer and lung metastasis

Recently, photodynamic therapy (PDT) emerges as a promising way to initiate immune response and being used in combination with chemotherapy. However, the antitumor effect is restricted due to the poor tumor penetration and retention, premature drug release and immunosuppressive environment of tumor sites. And as the size of nanoparticles plays a key role in drug delivery, series of hyaluronidase-responsive size-reducible biomimetic nanoparticles (mCAuNCs@HA) with different initial sizes are synthesized, and the optimal size of 150 nm is screened out because of the best blood circulation, tumor penetration and retention. Then the photosensitizer pheophorbide A and ROS-responsive paclitaxel dimer prodrug (PXTK) are co-loaded to facilitate on-demand drug release. The hydrolysis byproduct cinnamaldehyde in turn stimulates the ROS production by mitochondria, which compensates for the ROS consumed in the hydrolysis process. Anti-PD-L1 peptide (dPPA) is furthered loaded to alleviate the immunosuppressive environment of tumor and enhance the function of cytotoxic T lymphocytes activated by PDT-induced immunogenic cell death. The combination therapy activates CD4⁺, CD8⁺ T cells and NK cells and enhances secretion of cytokines (TNF-α and IL-12) with tumor inhibition rate increased to 84.2% and no metastasis is observed, providing a viable combination therapy for better anti-tumor and anti-metastasis efficacy.

Spatiotemporally Light-Activatable Platinum Nanocomplexes for Selective and Cooperative Cancer Therapy

Highly efficient nanoarchitectures are of great interest for achieving precise chemotherapy with minimized adverse side effects in cancer therapy. However, a major challenge remains in exploring a rational approach to synthesize spatiotemporally selective vehicles for precise cancer chemotherapy. Here, we demonstrate a rational design of bifunctional light-activatable platinum nanocomplexes (PtNCs) that produce dually cooperative cancer therapy through spatiotemporally selective thermo-chemotherapy. The Pt⁴⁺-coordinated polycarboxylic nanogel is explored as the nanoreactor template, which is exploited to synthesize bifunctional PtNCs consisting of a zero-valent Pt⁰ core and a surrounding bivalent Pt²⁺ shell with tunable ratios through a facile and controllable reduction. Without light exposure, chemotherapeutic Pt²⁺ ions are tightly bound on the surface of PtNCs, efficiently reducing undesirable drug leakage and nonselective damage on normal tissues/cells. Upon light exposure, PtNCs generate much heat via photothermal conversion from the Pt⁰ core and simultaneously trigger a rapid release of chemotherapeutic Pt²⁺ ions, thereby leading to the spatiotemporally light-activatable synergistic effect of thermo-chemotherapy. Moreover, PtNCs show enhanced tumor accumulation through the heat-triggered hydrophilicity-hydrophobicity transition upon immediate light exposure after injection, dramatically facilitating in vivo tumor regression through their cooperative anticancer efficiency. This rational design of spatiotemporally activatable nanoparticles provides an insightful tool for precise cancer therapy.

A NIR-responsive indocyanine green-genistein nanoformulation to control the polycomb epigenetic machinery for the efficient combinatorial photo/chemotherapy of glioblastoma

Combinatorial photodynamics and chemotherapy have drawn enormous attention as therapeutic modalities via precise stimuli-responsive drug delivery for glioblastoma, which can overcome the limitations associated with conventional therapies. Herein, we have prepared an indocyanine green tagged, genistein encapsulated casein nanoformulation (ICG-Gen@CasNPs) that exhibits the near infra-red region responsive controlled release of genistein and enhanced cellular uptake in the human glioblastoma monolayer and a three-dimensional raft culture model via the enhanced retention effect. ICG-Gen@CasNPs, with the integrated photosensitizer indocyanine green within the nanoformulation, triggered oxidative stress, activating the apoptosis cascade, promoting cell cycle arrest and damaging the mitochondrial membrane potential, collectively directing glioblastoma cell death. The suppression of the polycomb group of proteins in the glioblastoma upon ICG-Gen@CasNPs/NIR exposure revealed the involvement of the epigenetic repression complex machinery in the regulation. Furthermore, ICG-Gen@CasNPs/PDT/PTT directed ubiquitination and proteasomal degradation of EZH2 and BMI1 indicates the implication of the polycomb in conferring glioblastoma survival. The increased activation of the apoptotic pathways and the generation of cellular reactive oxygen species upon inhibiting the expression of EZH2 and BMI1 strengthen our observations. It is worth noting that ICG-Gen@CasNPs robustly accumulated in the brain after crossing the blood-brain barrier, which represents the eminent biocompatibility and means that the system is devoid of any nonspecific toxicity in vivo. Moreover, a superior anti-tumor effect was demonstrated on a three-dimensional glioma spheroid model. Thus, this combinatorial chemo/photodynamic therapy revealed that ICG-Gen@CasNPs mediated epigenetic regulation, which is a crucial molecular mechanism of GBM suppression.

Recent Advances on Reactive Oxygen Species-Responsive Delivery and Diagnosis System

Reactive oxygen species (ROS) play crucial roles in biological metabolism and intercellular signaling. However, ROS level is dramatically elevated due to abnormal metabolism during multiple pathologies, including neurodegenerative diseases, diabetes, cancer, and premature aging. By taking advantage of the discrepancy of ROS levels between normal and diseased tissues, a variety of ROS-sensitive moieties or linkers have been developed to design ROS-responsive systems for the site-specific delivery of drugs and genes. In this review, we summarized the ROS-responsive chemical structures, mechanisms, and delivery systems, focusing on their current advances for precise drug/gene delivery. In particular, ROS-responsive nanocarriers, prodrugs, and supramolecular hydrogels are summarized in terms of their application for drug/gene delivery, and common strategies to elevate or diminish cellular ROS concentrations, as well as the recent development of ROS-related imaging probes were also discussed.

Oriented Assembly of Cell-Mimicking Nanoparticles via a Molecular Affinity Strategy for Targeted Drug Delivery

Cell membrane cloaking is an emerging field in drug delivery in which specific functions of parent cells are conferred to newly formed biomimetic vehicles. A growing variety of delivery systems with diverse surface properties have been utilized for this strategy, but it is unclear whether the affinity of membrane-core pairs could guarantee effective and proper camouflaging. In this study, we propose a concise and effective "molecular affinity" strategy using the intracellular domain of transmembrane receptors as "grippers" during membrane coating. Red blood cell (RBC) membranes and cationic liposomes were adopted for fabrication, and a peptide ligand derived from the cytoplasmic protein P4.2 was prepared to specifically recognize the cytoplasmic domain of band 3, a key transmembrane receptor of erythrocytes. Once anchored onto the liposome surface, the P4.2-derived peptide would interact with the isolated RBC membrane, forming a "hidden peptide button", which ensures the right-side-out orientation. The membrane-coated liposomes exhibited an appropriate size distribution around 100 nm and high stability, with superior circulation durations compared with those of conventional PEGylated liposomes. Importantly, they possessed the ability to target Candida albicans by the interaction between the pathogenic fungus and host erythrocytes and to neutralize hemotoxin secreted by the pathogenic fungi. The curative effect of the model drug was thus substantially improved. In summary, the "molecular affinity" strategy may provide a powerful and universal approach for the construction of cell membrane-coated biomaterials and nanomedicines at both laboratory and industrial scales.

Fabrication of red blood cell membrane-camouflaged Cu2-xSe nanoparticles for phototherapy in the second near-infrared window

Cu_2-xSe nanoparticles (Cu_2-xSeNPs) were camouflaged with a red blood cell membrane (RBC) to create nanoparticles with improved biocompatibility, longer blood retention times, excellent absorption properties, superior photothermal conversion efficiency (67.2%) and singlet oxygen production capabilities for the synergistic photothermal and photodynamic therapy of cancer in the second near-infrared (NIR-II) window.

Self-Assembled Oxaliplatin(IV) Prodrug-Porphyrin Conjugate for Combinational Photodynamic Therapy and Chemotherapy

Nanomedicine has emerged as a promising strategy for effective cancer treatment. A useful approach is to develop carrier-free nanodrugs via a facile supramolecular self-assembly process. To achieve high therapeutic effect, integrating photodynamic therapy with chemotherapy has been sought after. In this work, we designed a nanocarrier (PEG-Por-CD: oxliPt(IV)-ada) assembled with oxaliplatin prodrug (oxliPt(IV)-ada) and porphyrin photosensitizer (PEG-Por-CD) through host-guest interaction to achieve stimulus-responsive combination therapy. Contributed by excellent spatial control of the binding ratio between host and guest molecules, porphyrin and oxaliplatin were separately modified with β-cyclodextrin and adamantane to prepare the amphiphilic host-guest complex for subsequent self-assembly into therapeutic nanoparticles. The obtained PEG-Por-CD: oxliPt(IV)-ada nanoparticles exhibited good colloidal stability with an average hydrodynamic size of 164 nm while undergoing the disassembly under reductive environment to release active therapeutic species. Confocal imaging demonstrated the ability of PEG-Por-CD: oxliPt(IV)-ada to effectively accumulate in the cells and produce reactive oxygen species in vitro upon 630 nm light irradiation. As compared with the monotherapy, the PEG-Por-CD: oxliPt(IV)-ada nanoparticles exhibited 3-fold enhanced cytotoxicity and 2-fold increase in the apoptosis. In vivo experiments using 4T1 tumor-bearing mice confirmed that the nanoparticles were efficient in suppressing the tumor growth without eliciting systemic toxicity. The present self-delivery nanosystem constructed from the self-assembly approach not only allows precise control over the drug and photosensitizer loading ratio but also eliminates systemic toxicity concern of the drug carriers, providing a solution for further development of combinational cancer treatment.

Biodistribution and toxicological evaluation of micron- and nano-sized erythrocyte-derived optical particles in healthy Swiss Webster mice

Particle-based systems provide a capability for the delivery of imaging and/or therapeutic payloads. We have engineered constructs derived from erythrocytes, and doped with the FDA-approved near infrared dye, indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micron- to nano-scale. Herein, we investigated the effects of micron- (≈2.6 μm diameter), and nano- (≈145 nm diameter) sized NETs on their biodistribution, and evaluated their acute toxicity in healthy Swiss Webster mice. Following tail vein injection of free ICG and NETs, animals were euthanized at various time points up to 48 hours. Fluorescence analysis of blood showed that nearly 11% of the injected amount of nano-sized NETs (nNETs) remained in blood at 48 hours post-injection as compared to ≈5% for micron-sized NETs (μNETs). Similarly, at this time point, higher levels of nNETs were present in various organs including the lungs, liver, and spleen. Histological analyses of various organs, extracted at 24 hours post-injection of NETs, did not show pathological alterations. Serum biochemistry profiles, in general, did not show elevated levels of the various analyzed biomarkers associated with liver and kidney functions. Values of various hematological profiles remained within the normal ranges following the administration of μNETs and nNETs. Results of this study suggest that erythrocyte-derived particles can potentially provide a non-toxic platform for delivery of ICG.

AIE Multinuclear Ir(III) Complexes for Biocompatible Organic Nanoparticles with Highly Enhanced Photodynamic Performance

The singlet oxygen (1O2) generation ability of a photosensitizer (PS) is pivotal for photodynamic therapy (PDT). Transition metal complexes are effective PSs, owing to their high 1O2 generation ability. However, non-negligible cellular toxicity, poor biocompatibility, and easy aggregation in water limit their biomedical applications. In this work, a series of red-emitting aggregation-induced emission (AIE) Ir(III) complexes containing different numbers of Ir centers (mono-, di-, and trinuclear) and the corresponding nanoparticles (NPs) AIE-NPs, are designed and synthesized. The increase of 1O2 generation ability is in line with the increasing number of Ir centers. Compared with the pure Ir(III) complexes, the corresponding NPs offer multiple advantages: (i) brighter emission; (ii) higher phosphorescence quantum yields; (iii) longer excited lifetime; (iv) higher 1O2 generation ability; (v) better biocompatibility; and (vi) superior cellular uptake. Both in vitro and in vivo experiments corroborate that AIE-NPs with three iridium centers possess potent cytotoxicity toward cancer cells and effective inhibition of tumor growth. To the best of knowledge, this work is the first example of NPs of multinuclear AIE Ir(III) complexes as PSs for enhanced PDT. This study offers a new method to improve the efficiency of PSs for clinical cancer treatments.

Photothermal-Controlled Generation of Alkyl Radical from Organic Nanoparticles for Tumor Treatment

The therapeutic properties of light are well known for photodynamic or photothermal therapy, which could cause irreversible photodamage to tumor tissues. Although photodynamic therapy (PDT) has been proved in the clinic, the efficacy is not satisfactory because of complicated tumor microenvironments. For example, the hypoxia in solid tumor has a negative effect on the generation of singlet oxygen. To address the hypoxia issues in PDT, leveraging alkyl radical is an available option due to the oxygen-independent feature. In this work, a new kind of organic nanoparticles (tripolyphosphate (TPP)-NN NPs) from porphyrin and radical initiator is developed. Under near-infrared light irradiation, TPP-NN NPs will split and release alkyl radical, which could induce obvious cytotoxicity both in normal and hypoxia environment. The photothermal-controlled generation of alkyl radical could significantly inhibit the growth of cervical cancer and show ignorable systemic toxicity. This activatable radical therapy opens up new possibilities for the application of PDT in hypoxia condition.

Green Mass Production of Pure Nanodrugs via an Ice-Template-Assisted Strategy

To make nanomedicine potentially applicable in a clinical setting, several methods have been developed to synthesize pure nanodrugs (PNDs) without using any additional inert carriers. In this work, we report a novel green, low-cost, and scalable ice-template-assisted approach which shows several unique characteristics. First, the whole process only requires adding a drug solution into an ice template and subsequent melting (or freeze-drying), allowing easy industrial mass production with low capital investment. Second, the production yield is much higher than that of the traditional reprecipitation approach. The yield of Curcumin (Cur) PNDs is over two orders (∼140 times) magnitude higher than that obtained in a typical reprecipitation preparation. By adjusting simple processing parameters, PNDs with different sizes (∼20-200 nm) can be controllably obtained. Finally, the present approach can be easily applicable for a wide range of hydrophobic therapeutic drugs without any structural modification.

Recent Advances in Subcellular Targeted Cancer Therapy Based on Functional Materials

Recently, diverse functional materials that take subcellular structures as therapeutic targets are playing increasingly important roles in cancer therapy. Here, particular emphasis is placed on four kinds of therapies, including chemotherapy, gene therapy, photodynamic therapy (PDT), and hyperthermal therapy, which are the most widely used approaches for killing cancer cells by the specific destruction of subcellular organelles. Moreover, some non-drug-loaded nanoformulations (i.e., metal nanoparticles and molecular self-assemblies) with a fatal effect on cells by influencing the subcellular functions without the use of any drug molecules are also included. According to the basic principles and unique performances of each treatment, appropriate strategies are developed to meet task-specific applications by integrating specific materials, ligands, as well as methods. In addition, the combination of two or more therapies based on multifunctional nanostructures, which either directly target specific subcellular organelles or release organelle-targeted therapeutics, is also introduced with the intent of superadditive therapeutic effects. Finally, the related challenges of critical re-evaluation of this emerging field are presented.