Surface functionalization of gold nanoparticles with red blood cell membranes

Photothermal therapies to improve immune checkpoint blockade for cancer

Immune checkpoint blockade (ICB) comprising monoclonal antibodies (mAbs) against immune 'checkpoints', such as CTLA-4 and the PD1/PDL1 axis have dramatically improved clinical outcomes for patients with cancer. However, ICB by itself has failed to provide benefit in a wide range of solid tumors, where recurrence still occurs with high incidence. These poor response rates may be due to the therapeutic shortcomings of ICB; namely, a lack of cancer-specific cytotoxicity and ability to debulk tumors. To overcome these limitations, effective ICB therapy may require the combination with other complementary therapeutic platforms. Here, we propose that photothermal therapy (PTT) is an ideal therapeutic modality for combination with ICB because it can generate both tumor-specific cytotoxicity and immunogenicity. PTT elicits these specific effects because it is a localized thermal ablation technique that utilizes light-responsive nanoparticles activated by a wavelength-matched laser. While ICB immunotherapy alone improves cancer immunogenicity but does not generate robust antitumor cytotoxicity, nanoparticle-based PTT elicits targeted and controlled cytotoxicity but sub-optimal long-term immunogenicity. Thus, the two platforms offer complementary and potentially synergistic antitumor effects, which will be detailed in this review. We highlight three classes of nanoparticles used as agents of PTT (i.e., metallic inorganic nanoparticles, carbon-based nanoparticles and organic dyes), and illustrate the potential for nanoparticle-based PTT to potentiate the effects of ICB in preclinical models. Through this discussion, we aim to present PTT combined with ICB as a potent synergistic combination treatment for diverse cancer types currently refractory to ICB as well as PTT monotherapies.

Cu-doped cerium oxide-based nanomedicine for tumor microenvironment-stimulative chemo-chemodynamic therapy with minimal side effects

CeO₂ nanoenzyme possesses multiple enzyme-mimicking activities and excellent biocompatibility. However, its weak peroxidase (POD)-mimicking property in the tumor microenvironment (TME) hinders its further tumor therapy application. To enhance CeO₂ nanoenzyme's POD activity and overcome limitations of single therapeutic modality, a novel antitumor controlled drug release system (CCCs NPs) was designed using Cu doped cerium oxide nanoparticles (Cu-CeO₂ NPs) loaded with clinical anti-cancer drug doxorubicin (DOX) as the core and the breast cancer cell membrane as the outer shell. Cu doping endowed CeO₂ NPs' with significantly enhanced POD-mimicking activity in the TME due to a remarkably higher Ce³⁺/Ce⁴⁺ ratio. The cancer cell membrane coating enabled our nanomedicine with homotypic targeting property. Combined with chemotherapeutic drug DOX, a selective and nearly complete tumor suppression was demonstrated in vitro and in vivo. Remarkably, under physiological condition, CCCs NPs worked as a radical scavenger to protect normal cells from oxidative stress caused by anti-cancer drug DOX and OH generated via Fenton-like reaction. Collectively, our CCCs NPs offered a therapeutic potential for effective breast cancer therapy while being free of side effects.

Biomimetic camouflage delivery strategies for cancer therapy

Cancer remains a significant challenge despite the progress in developing different therapeutic approaches. Nanomedicine has been explored as a promising novel cancer therapy. Recently, biomimetic camouflage strategies have been investigated to change the bio-fate of therapeutics and target cancer cells while reducing the unwanted exposure on normal tissues. Endogenous components (e.g., proteins, polysaccharides, and cell membranes) have been used to develop anticancer drug delivery systems. These biomimetic systems can overcome biological barriers and enhance tumor cell-specific uptake. The tumor-targeting mechanisms include ligand-receptor interactions and stimuli-responsive (e.g., pH-sensitive and light-sensitive) delivery. Drug delivery carriers composed of endogenous components represent a promising approach for improving cancer treatment efficacy. In this paper, different biomimetic drug delivery strategies for cancer treatment are reviewed with a focus on the discussion of their advantages and potential applications.

4T1 cell membrane fragment reunited PAMAM polymer units disguised as tumor cell clusters for tumor homotypic targeting and anti-metastasis treatment

Cell membrane-based nanoparticles have garnered increasing attention owing to their inherent biomimetic properties, such as homotypic targeting, prolong circulation, and immune escaping mechanisms. However, most of these biomimetic nanoparticles appear as an orientated core-shell unit because of the lack of the full utilization and direction control of membranes. Different from those single-unit delivery systems, we reported a multiple-unit nanocluster by randomly reuniting multiple PAMAM polymeric core units into a single nanocluster via simple electrostatic interactions between 4T1 cell membrane fragments and PAMAM. Similar to tumor cell clusters, the doxorubicin (DOX)-loaded nanoclusters (CCNCs) could actively metastasis towards cancer cells after getting access to the systemic circulation due to their specific homotypic targeting ability. In this study, CCNCs showed significantly higher tumor inhibition efficacy in 4T1 tumor-bearing mice compared with that of free DOX and PAMAM@DOX-treated groups. Furthermore, the quantitative analysis showed that the number of pulmonary metastatic nodules remarkably reduced, indicating the potential anti-metastasis effect of CCNCs. Overall, these tumor cell membrane fragment reunited PAMAM polymer units could disguise as tumor cell clusters for encouraging tumor homotypic targeting and anti-metastasis treatment.

Rethinking CRITID Procedure of Brain Targeting Drug Delivery: Circulation, Blood Brain Barrier Recognition, Intracellular Transport, Diseased Cell Targeting, Internalization, and Drug Release

The past decades have witnessed great progress in nanoparticle (NP)-based brain-targeting drug delivery systems, while their therapeutic potentials are yet to be fully exploited given that the majority of them are lost during the delivery process. Rational design of brain-targeting drug delivery systems requires a deep understanding of the entire delivery process along with the issues that they may encounter. Herein, this review first analyzes the typical delivery process of a systemically administrated NPs-based brain-targeting drug delivery system and proposes a six-step CRITID delivery cascade: circulation in systemic blood, recognizing receptor on blood-brain barrier (BBB), intracellular transport, diseased cell targeting after entering into parenchyma, internalization by diseased cells, and finally intracellular drug release. By dissecting the entire delivery process into six steps, this review seeks to provide a deep understanding of the issues that may restrict the delivery efficiency of brain-targeting drug delivery systems as well as the specific requirements that may guarantee minimal loss at each step. Currently developed strategies used for troubleshooting these issues are reviewed and some state-of-the-art design features meeting these requirements are highlighted. The CRITID delivery cascade can serve as a guideline for designing more efficient and specific brain-targeting drug delivery systems.

Coagulation-Inspired Direct Fibrinogen Assay Using Plasmonic Nanoparticles Functionalized with Red Blood Cell Membranes

The fast measurement of fibrinogen is essential in evaluating life-threatening sepsis and cardiovascular diseases. Here, we aim to utilize biomimetic plasmonic Au nanoparticles using red blood cell membranes (RBCM-AuNPs) and demonstrate nanoscale coagulation-inspired fibrinogen detection via cross-linking between RBCM-AuNPs. The proposed biomimetic RBCM-AuNPs are highly suitable for fibrinogen detection because hemagglutination, occurring in the presence of fibrinogen, induces a shift in the localized surface plasmon resonance of the NPs. Specifically, when the two ends of the fibrinogen protein are bound to receptors on separate RBCM-AuNPs, cross-linking of the RBCM-AuNPs occurs, yielding a corresponding plasmon shift within 10 min. This coagulation-inspired fibrinogen detection method, with a low sample volume, high selectivity, and high speed, could facilitate the diagnosis of sepsis and cardiovascular diseases.

Erythrocyte-camouflaged biosensor for α-hemolysin detection

Without appropriate treatment, Staphylococcus aureus (S. aureus) infection can cause life-threatening diseases (e.g., meningitis, pneumonia, bacteremia, and sepsis). However, a rapid and accurate point-of-care test for the infection remains challenging. The bacterium secretes α-hemolysin (Hla), which spontaneously binds to the cell membrane of erythrocyte, and eventually lyses the cell via pore formation. Taking advantage of this phenomenon, we apply the erythrocyte membrane (EM) extracted from human whole blood as a novel bioreceptor for detecting Hla, fabricating erythrocyte-camouflaged biosensors (ECB) by coating EM onto electrochemical impedance electrodes. We verify the existence of EM on the ECB by using confocal microscopy and atomic force microscopy. We demonstrate that ECBs sensitively detect Hla spiked in phosphate buffer saline and human serum. Also, the sensor shows higher sensitivity to Hla than major blood proteins, such as human serum albumin, fibrinogen, and gamma globulin. Specifically, the signal intensities for Hla are 8.8-12.7 times higher than those in the same concentration of those blood proteins. The detection limit of the ECB for Hla is 1.9 ng/ml while the dynamic range is 0.0001-1 mg/ml. Finally, we validate the constant sensing performance of ECB with 99.0 ± 5.6% accuracy for 35 days of storage.

Biomimetic Nanoscale Erythrocyte Delivery System for Enhancing Chemotherapy via Overcoming Biological Barriers

Overcoming multiple biological barriers, including circulation time in vivo, tumor vascular endothelium, reticuloendothelial system (RES), extracellular matrix (ECM), etc., is the key to improve the therapeutic efficacy of drug delivery systems in treating tumors. Inspired by the ability of natural erythrocytes to cross multiple barriers, in this study, a biomimetic delivery system named NE@DOX-Ang2 was developed for enhancing the chemotherapy of breast cancer, which employed nano-erythrocyte (NE) encapsulating doxorubicin (DOX) and surface modification with a targeted angiopep-2 peptide (Ang2). NE@DOX-Ang2 enhanced the capacity to cross biological barriers in a three-dimensional (3D) tumor spheroid model and in vivo in mice. Compared with a conventional drug delivery system of liposomes, the half-life of NE@DOX-Ang2 increased approximately 2.5 times. Moreover, NE@DOX-Ang2 exhibited excellent tumor-targeting ability and antitumor effects in vitro and in vivo. Briefly, the prepared nano-erythrocyte drug carrier has features of favorable biocompatibility and low immunogenicity and the advantage of prolonging the half-life of drugs, which may provide a novel perspective for development of clinically available nanomedicines.

Ultrasound-assisted fabrication of acoustically active, erythrocyte membrane "bubbles"

In this communication, we report an ultrasound-assisted method, utilising human red blood cell (RBC) or erythrocyte membranes, to produce acoustically active "bubbles", intended for vasculature imaging. The resulting RBC membrane bubbles have an average size of 1.5 μm with a generally spherical morphology, altered internal aqueous compartment contents, and small gas-containing protrusions or "pockets" in between the membrane bilayer. We also found that this method produced some nanobubbles (200-400 nm diameter), due to the shedding of lipid components from the RBC membranes to compensate for the membrane structural changes. In vitro ultrasound imaging showed that RBC membrane bubbles had comparable ultrasound contrast enhancement as the standard DEFINTY^TM microbubble preparation (~13% v/v) and lower concentrations of this standard contrast agent. This current technology demonstrate a new and important application of ultrasound and of RBC membranes, having inherent biocompatibility, as potential material for the development of new types of ultrasound imaging agents, without the use of additional lipid components and pre-made microbubbles.

Nanotechnology advances in pathogen- and host-targeted antiviral delivery: multipronged therapeutic intervention for pandemic control

The COVID-19 pandemic's high mortality rate and severe socioeconomic impact serve as a reminder of the urgent need for effective countermeasures against viral pandemic threats. In particular, effective antiviral therapeutics capable of stopping infections in its tracks is critical to reducing infection fatality rate and healthcare burden. With the field of drug delivery witnessing tremendous advancement in the last two decades owing to a panoply of nanotechnology advances, the present review summarizes and expounds on the research and development of therapeutic nanoformulations against various infectious viral pathogens, including HIV, influenza, and coronaviruses. Specifically, nanotechnology advances towards improving pathogen- and host-targeted antiviral drug delivery are reviewed, and the prospect of achieving effective viral eradication, broad-spectrum antiviral effect, and resisting viral mutations are discussed. As several COVID-19 antiviral clinical trials are met with lackluster treatment efficacy, nanocarrier strategies aimed at improving drug pharmacokinetics, biodistributions, and synergism are expected to not only contribute to the current disease treatment efforts but also expand the antiviral arsenal against other emerging viral diseases.

MSCs-engineered biomimetic PMAA nanomedicines for multiple bioimaging-guided and photothermal-enhanced radiotherapy of NSCLC

Background

The recently developed biomimetic strategy is one of the mostly effective strategies for improving the theranostic efficacy of diverse nanomedicines, because nanoparticles coated with cell membranes can disguise as “self”, evade the surveillance of the immune system, and accumulate to the tumor sites actively.

Results

Herein, we utilized mesenchymal stem cell memabranes (MSCs) to coat polymethacrylic acid (PMAA) nanoparticles loaded with Fe(III) and cypate—an derivative of indocyanine green to fabricate Cyp-PMAA-Fe@MSCs, which featured high stability, desirable tumor-accumulation and intriguing photothermal conversion efficiency both in vitro and in vivo for the treatment of lung cancer. After intravenous administration of Cyp-PMAA-Fe@MSCs and Cyp-PMAA-Fe@RBCs (RBCs, red blood cell membranes) separately into tumor-bearing mice, the fluorescence signal in the MSCs group was 21% stronger than that in the RBCs group at the tumor sites in an in vivo fluorescence imaging system. Correspondingly, the T₁-weighted magnetic resonance imaging (MRI) signal at the tumor site decreased 30% after intravenous injection of Cyp-PMAA-Fe@MSCs. Importantly, the constructed Cyp-PMAA-Fe@MSCs exhibited strong photothermal hyperthermia effect both in vitro and in vivo when exposed to 808 nm laser irradiation, thus it could be used for photothermal therapy. Furthermore, tumors on mice treated with phototermal therapy and radiotherapy shrank 32% more than those treated with only radiotherapy.

Conclusions

These results proved that Cyp-PMAA-Fe@MSCs could realize fluorescence/MRI bimodal imaging, while be used in phototermal-therapy-enhanced radiotherapy, providing desirable nanoplatforms for tumor diagnosis and precise treatment of non-small cell lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00823-6.

Cancer Cell-Membrane Biomimetic Boron Nitride Nanospheres for Targeted Cancer Therapy

PURPOSE

Nanomaterial-based drug-delivery systems allowing for effective targeted delivery of smallmolecule chemodrugs to tumors have revolutionized cancer therapy. Recently, as novel nanomaterials with outstanding physicochemical properties, boron nitride nanospheres (BNs) have emerged as a promising candidate for drug delivery. However, poor dispersity and lack of tumor targeting severely limit further applications. In this study, cancer cell-membrane biomimetic BNs were designed for targeted anticancer drug delivery.

METHODS

Cell membrane extracted from HeLa cells (HM) was used to encapsulate BNs by physical extrusion. Doxorubicin (Dox) was loaded onto HM-BNs as a model drug.

RESULTS

The cell-membrane coating endowed the BNs with excellent dispersibility and cytocompatibility. The drug-release profile showed that the Dox@HM-BNs responded to acid pH, resulting in rapid Dox release. Enhanced cellular uptake of Dox@HM-BNs by HeLa cells was revealed because of the homologous targeting of cancer-cell membranes. CCK8 and live/dead assays showed that Dox@HM-BNs had stronger cytotoxicity against HeLa cells, due to self-selective cellular uptake. Finally, antitumor investigation using the HeLa tumor model demonstrated that Dox@HM-BNs possessed much more efficient tumor inhibition than free Dox or Dox@BNs.

CONCLUSION

These findings indicate that the newly developed HM-BNs are promising as an efficient tumor-selective drug-delivery vehicle for tumor therapy.

Erythrocytes and Nanoparticles: New Therapeutic Systems

Nano-delivery systems represent one of the most studied fields, thanks to the associated improvement in the treatment of human diseases. The functionality of nanostructures is a crucial point, which the effectiveness of nanodrugs depends on. A hybrid approach strategy using synthetic nanoparticles (NPs) and erythrocytes offers an optimal blend of natural and synthetic materials. This, in turn, allows medical practitioners to exploit the combined advantages of erythrocytes and NPs. Erythrocyte-based drug delivery systems have been investigated for their biocompatibility, as well as the long circulation time allowed by specific surface receptors that inhibit immune clearance. In this review, we will discuss several methods—whole erythrocytes as drug carriers, red blood cell membrane-camouflaged nanoparticles and nano-erythrosomes (NERs)—while paying attention to their application and specific preparation methods. The ability to target cells makes erythrocytes excellent drug delivery systems. They can carry a wide range of therapeutic molecules while also acting as bioreactors; thus, they have many applications in therapy and in the diagnosis of many diseases.

Inorganic Nanoparticles Applied for Active Targeted Photodynamic Therapy of Breast Cancer

Photodynamic therapy (PDT) is an alternative modality to conventional cancer treatment, whereby a specific wavelength of light is applied to a targeted tumor, which has either a photosensitizer or photochemotherapeutic agent localized within it. This light activates the photosensitizer in the presence of molecular oxygen to produce phototoxic species, which in turn obliterate cancer cells. The incidence rate of breast cancer (BC) is regularly growing among women, which are currently being treated with methods, such as chemotherapy, radiotherapy, and surgery. These conventional treatment methods are invasive and often produce unwanted side effects, whereas PDT is more specific and localized method of cancer treatment. The utilization of nanoparticles in PDT has shown great advantages compared to free photosensitizers in terms of solubility, early degradation, and biodistribution, as well as far more effective intercellular penetration and uptake in targeted cancer cells. This review gives an overview of the use of inorganic nanoparticles (NPs), including: gold, magnetic, carbon-based, ceramic, and up-conversion NPs, as well as quantum dots in PDT over the last 10 years (2009 to 2019), with a particular focus on the active targeting strategies for the PDT treatment of BC.

Smart Nanocarriers for Targeted Cancer Therapy

Cancer is considered one of the most threatening diseases worldwide. Although many therapeutic approaches have been developed and optimized for ameliorating patient's conditions and life expectancy, however, it frequently remains an incurable pathology. Notably, conventional treatments may reveal inefficient in the presence of metastasis development, multidrug resistance and inability to achieve targeted drug delivery. In the last decades, nanomedicine has gained a prominent role, due to many properties ascribable to nanomaterials. It is worth mentioning their small size, their ability to be loaded with small drugs and bioactive molecules and the possibility to be functionalized for tumor targeting. Natural vehicles have been exploited, such as exosomes, and designed, such as liposomes. Biomimetic nanomaterials have been engineered, by modification with biological membrane coating. Several nanoparticles have already entered clinical trials and some liposomal formulations have been approved for therapeutic applications. In this review, natural and synthetic nanocarriers functionalized for actively targeting cancer cells will be described, focusing on their advantages with respect to conventional treatments. Recent innovations related to biomimetic nanoparticles camouflaged with membranes isolated from different types of cells will be reported, together with their promising applications. Finally, a short overview on the latest advances in carrier-free nanomaterials will be provided.

Supramolecular metal-based nanoparticles for drug delivery and cancer therapy

Although conventional cancer therapies such as chemotherapy and radiotherapy prevail in clinic, they tend to have narrow therapeutic windows. Many chemotherapies have unfavorable pharmacokinetics while radiotherapy incurs radiotoxicity to normal tissues surrounding tumors. The chemical tunability of supramolecular metal-based nanoparticles (SMNPs) enables the incorporation of various therapeutics, including hydrophilic and hydrophobic chemotherapeutic drugs, photosensitizers, radiosensitizers, and biological therapeutics for more effective delivery to tumors. In this mini-review, we highlight recent advances in SMNPs, namely nanoscale coordination polymers and nanoscale metal-organic frameworks, for drug delivery and cancer therapy. We particularly focus on innovative uses of metal clusters, ligands, pores, and surface modifications to load various therapeutics into SMNPs and critical evaluations of the anticancer efficacies of SMNPs.

The Use of Alternative Strategies for Enhanced Nanoparticle Delivery to Solid Tumors

Nanomaterial (NM) delivery to solid tumors has been the focus of intense research for over a decade. Classically, scientists have tried to improve NM delivery by employing passive or active targeting strategies, making use of the so-called enhanced permeability and retention (EPR) effect. This phenomenon is made possible due to the leaky tumor vasculature through which NMs can leave the bloodstream, traverse through the gaps in the endothelial lining of the vessels, and enter the tumor. Recent studies have shown that despite many efforts to employ the EPR effect, this process remains very poor. Furthermore, the role of the EPR effect has been called into question, where it has been suggested that NMs enter the tumor via active mechanisms and not through the endothelial gaps. In this review, we provide a short overview of the EPR and mechanisms to enhance it, after which we focus on alternative delivery strategies that do not solely rely on EPR in itself but can offer interesting pharmacological, physical, and biological solutions for enhanced delivery. We discuss the strengths and shortcomings of these different strategies and suggest combinatorial approaches as the ideal path forward.

Polymeric micelles coated with hybrid nanovesicles enhance the therapeutic potential of the reversible topoisomerase inhibitor camptothecin in a mouse model

Nanoparticles with longer blood circulation, high loading capacity, controlled release at the targeted site, and preservation of camptothecin (CPT) in its lactone form are the key characteristics for the effective delivery of CPT. In this regard, natural membrane-derived nanovesicles, particularly those derived from RBC membrane, are important. RBC membrane can be engineered to form vesicles or can be coated over synthetic nanoparticles, without losing their basic structural features and can have prolonged circulation time. Here, we developed a hybrid system to encapsulate CPT inside the amphiphilic micelle and coat it with RBC membrane. Thus, it uses the dual ability of polymeric micelles to preserve CPT in its active form, while maintaining its "stealth" effect due to conserved RBC membrane coating. The hybrid system stabilized 60% of the drug in its active form even after 30 h of incubation in serum, in contrast to 15% active form present in free drug formulation after 1 h of incubation. It showed strong retention inside the Ehrlich Ascites Carcinoma (EAC) mice models for at least 72 h, suggesting camouflaging ability conferred by RBC membrane. Additionally, the nano formulation retarded the tumor growth rate more efficiently than free drug, with no evident signs of necrotic skin lesions. Histopathological analysis showed a significant reduction in cardiac atrophy, hepato-renal degeneration, and lung metastasis, which resulted in the increased overall survival of mice treated with the nano formulation. Hence, CPT-loaded polymeric micelles when coated with RBC membrane can prove to be a better system for the delivery of poorly soluble drug camptothecin.

Cell primitive-based biomimetic functional materials for enhanced cancer therapy

Cell primitive-based functional materials that combine the advantages of natural substances and nanotechnology have emerged as attractive therapeutic agents for cancer therapy. Cell primitives are characterized by distinctive biological functions, such as long-term circulation, tumor specific targeting, immune modulation etc. Moreover, synthetic nanomaterials featuring unique physical/chemical properties have been widely used as effective drug delivery vehicles or anticancer agents to treat cancer. The combination of these two kinds of materials will catalyze the generation of innovative biomaterials with multiple functions, high biocompatibility and negligible immunogenicity for precise cancer therapy. In this review, we summarize the most recent advances in the development of cell primitive-based functional materials for cancer therapy. Different cell primitives, including bacteria, phages, cells, cell membranes, and other bioactive substances are introduced with their unique bioactive functions, and strategies in combining with synthetic materials, especially nanoparticulate systems, for the construction of function-enhanced biomaterials are also summarized. Furthermore, foreseeable challenges and future perspectives are also included for the future research direction in this field.

Hybrid biomembrane-functionalized nanorobots for concurrent removal of pathogenic bacteria and toxins

With the rapid advancement of robotic research, it becomes increasingly interesting and important to develop biomimetic micro- or nanorobots that translate biological principles into robotic systems. We report the design, construction, and evaluation of a dual-cell membrane-functionalized nanorobot for multipurpose removal of biological threat agents, particularly concurrent targeting and neutralization of pathogenic bacteria and toxins. Specifically, we demonstrated ultrasound-propelled biomimetic nanorobots consisting of gold nanowires cloaked with a hybrid of red blood cell (RBC) membranes and platelet (PL) membranes. Such hybrid cell membranes have a variety of functional proteins associated with human RBCs and PLs, which give the nanorobots a number of attractive biological capabilities, including adhesion and binding to PL-adhering pathogens (e.g., Staphylococcus aureus bacteria) and neutralization of pore-forming toxins (e.g., α-toxin). In addition, the biomimetic nanorobots displayed rapid and efficient prolonged acoustic propulsion in whole blood, with no apparent biofouling, and mimicked the movement of natural motile cells. This propulsion enhanced the binding and detoxification efficiency of the robots against pathogens and toxins. Overall, coupling these diverse biological functions of hybrid cell membranes with the fuel-free propulsion of the nanorobots resulted in a dynamic robotic system for efficient isolation and simultaneous removal of different biological threats, an important step toward the creation of a broad-spectrum detoxification robotic platform.

The membrane axis of Alzheimer's nanomedicine

Alzheimer's disease (AD) is a major neurological disorder impairing its carrier's cognitive function, memory and lifespan. While the development of AD nanomedicine is still nascent, the field is evolving into a new scientific frontier driven by the diverse physicochemical properties and theranostic potential of nanomaterials and nanocomposites. Characteristic to the AD pathology is the deposition of amyloid plaques and tangles of amyloid beta (Aβ) and tau, whose aggregation kinetics may be curbed by nanoparticle inhibitors via sequence-specific targeting or nonspecific interactions with the amyloidogenic proteins. As literature implicates cell membrane as a culprit in AD pathogenesis, here we summarize the membrane axis of AD nanomedicine and present a new rationale that the field development may greatly benefit from harnessing our existing knowledge of Aβ-membrane interaction, nanoparticle-membrane interaction and Aβ-nanoparticle interaction.

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.

Delicately Designed Cancer Cell Membrane-Camouflaged Nanoparticles for Targeted 19F MR/PA/FL Imaging-Guided Photothermal Therapy

Our exploration of multimodal nanoprobes aims to combine photoacoustic (PA) imaging, ¹⁹F magnetic resonance (MR), and fluorescence (FL) imaging, which offers complementary advantages such as high spatial resolution, unlimited penetration, and high sensitivity to enable more refined images for accurate tumor diagnoses. In this research, perfluorocarbons (PFCs) and indocyanine green (ICG) are encapsulated by poly(lactic-co-glycolic acid) (PLGA) for intravital ¹⁹F MR/FL/PA tri-modal imaging-guided photothermal therapy. Then, it is coated with an A549 cancer cell membrane (AM) to fabricate versatile theranostic nanoprobes (AM-PP@ICGNPs). After systemic administration, FLI reveals time-dependent tumor homing of NPs with high sensitivity, ¹⁹F MRI provides tumor localization of NPs without background signal interference, and PAI illustrates the detailed distribution of NPs inside the tumor with high spatial resolution. What is more, AM-PP@ICGNPs accumulated in the tumor area exhibit a prominent photothermal effect (48.4 °C) under near infrared (NIR) laser irradiation and realize an enhanced antitumor response in vivo. These benefits, in combination with the excellent biocompatibility, make AM-PP@ICGNPs a potential theranostic nanoagent for accurate tumor localization and ultimately achieve superior cancer therapy.

Fighting Immune Cold and Reprogramming Immunosuppressive Tumor Microenvironment with Red Blood Cell Membrane-Camouflaged Nanobullets

Nanomedicine, acting as the magic bullet, is capable of combining immunotherapy with other treatments to reverse a cold tumor (immune depletion) into a hot tumor. However, how to comprehensively inhibit the immunosuppressive tumor microenvironment (TME) remains a major challenge for immunotherapy to achieve the maximum benefits. Thus, a strategy that can simultaneously increase the recruitment of tumor infiltrating lymphocytes (TILs) and comprehensively reprogram the immunosuppressive TME is still urgently needed. Herein, a thermal-sensitive nitric oxide (NO) donor S-nitrosothiols (SNO)-pendant copolymer (poly(acrylamide-co-acrylonitrile-co-vinylimidazole)-SNO copolymer, PAAV-SNO) with upper critical solution temperature (UCST) was synthesized and employed to fabricate an erythrocyte membrane-camouflaged nanobullet for codelivery of NIR II photothermal agent IR1061 and indoleamine 2,3-dioxygenase 1 (IDO-1) inhibitor 1-methyl-tryptophan (1-MT). This multifunctional nanobullet possessed long circulation in vivo, enhanced accumulation at the tumor site, and therapeutics-controlled release by NIR II laser, thereby it could avoid unspecific drug leakage while enhancing biosecurity. More importantly, the immunogenic cell death (ICD) induced by local hyperthermia from photothermal therapy (PTT) could be conducive for the increased recruitment of CD8+ cytotoxic T lymphocytes (CTLs) at the tumor site. Furthermore, through interfering in the IDO-1 activity by 1-MT and normalizing the tumor vessels by in situ generated NO, the immunosuppressive TME was comprehensively reprogrammed toward an immunostimulatory phenotype, achieving the excellent therapeutic efficacy against both primary breast cancer and metastases. Collectively, this multifunctional nanobullet described in this study developed an effective and promising strategy to comprehensively reprogram suppressive TME and treat "immune cold" tumors.

Biomimetic nanoarchitecturing: A disguised attack on cancer cells

With the changing face of healthcare, there is a demand for drug delivery systems that have increased efficacy and biocompatibility. Nanotechnology derived drug carrier systems were found to be ideal candidates to meet these demands. Among the vast number of nanosized delivery systems, biomimetic nanoparticles have been researched at length. These nanoparticles mimic cellular functions and are highly biocompatible. They are also able to avoid clearance by the reticuloendothelial system which increases the time spent by them in the systemic circulation. Additionally, their low immunogenicity and targeting ability increase their significance as drug carriers. Based on their core material we have summarized them as biomimetic inorganic nanoparticles, biomimetic polymeric nanoparticles, and biomimetic lipid nanoparticles. The core then may be coated using membranes derived from erythrocytes, cancer cells, leukocytes, stem cells, and other membranes to endow them with biomimetic properties. They can be used for personalized therapy and diagnosis of a large number of diseases, primarily cancer. This review summarizes the various therapeutic approaches using biomimetic nanoparticles along with their applications in the field of cancer imaging, nucleic acid therapy and theranostic properties. A brief overview about toxicity concerns related to these nanoconstructs has been added to provide knowledge about biocompatibility of such nanoparticles.

Surface modification of black phosphorus-based nanomaterials in biomedical applications: Strategies and recent advances

Black phosphorus-based nanomaterials (BPNMs), an emerging member of two-dimensional (2D) nanomaterials, possess excellent physicochemical properties and hold great potential for application in advanced nanomedicines. However, the bare BPNMs easily decrease their biomedical activities due to their degradability and in vivo interactions with biological macromolecules such as plasma proteins, largely restricting their biomedical application. A variety of surface modifications, via chemical, physical or biological approaches, have been developed for BPNMs to avoid these limitations and achieve stable, long-lasting and safe therapeutic effects, thus enlighten the development of the multifunctional BPNMs for more practical application in the field of biomedicine. The present review summarizes the recent advances in the surface modification of BPNMs and the resultant expansion of their biomedical applications. Focus is put on the strategy and method of modification while the effects incurred on the behavior and potential toxicity of BPNMs are also included. The future and challenge of the surface modification of the therapeutic BPNMs are finally discussed.

RBC-derived vesicles as a systemic delivery system of doxorubicin for lysosomal-mitochondrial axis-improved cancer therapy

Introduction

Chemotherapeutic drugs are the main intervention for cancer management, but many drawbacks impede their clinical applications. Nanoparticles as drug delivery systems (DDSs) offer much promise to solve these limitations.

Objectives

A novel nanocarrier composed of red blood cell (RBC)-derived vesicles (RDVs) surface-linked with doxorubicin (Dox) using glutaraldehyde (glu) to form Dox-gluRDVs was investigated for improved cancer therapy.

Methods

We investigated the in vivo antineoplastic performance of Dox-gluRDVs through intravenous (i.v.) administration in the mouse model bearing subcutaneous (s.c.) B16F10 tumor and examined the in vitro antitumor mechanism and efficacy in a panel of cancer cell lines.

Results

Dox-gluRDVs can exert superior anticancer activity than free Dox in vitro and in vivo. Distinct from free Dox that is mainly located in the nucleus, but instead Dox-gluRDVs release and efficiently deliver the majority of their conjugated Dox into lysosomes. In vitro mechanism study reveals the critical role of lysosomal Dox accumulation-mediated mitochondrial ROS overproduction followed by the mitochondrial membrane potential loss and the activation of apoptotic signaling for superior anticancer activity of Dox-gluRDVs.

Conclusion

This work demonstrates the great potential of RDVs to serve a biological DDS of Dox for systemic administration to improve conventional cancer chemotherapeutics.

In vivo nano-biosensing element of red blood cell-mediated delivery

Biosensors based on nanotechnology are developing rapidly and are widely applied in many fields including biomedicine, environmental monitoring, national defense and analytical chemistry, and have achieved vital positions in these fields. Novel nano-materials are intensively developed and manufactured for potential biosensing and theranostic applications while lacking comprehensive assessment of their potential health risks. The integration of diagnostic in vivo biosensors and the DDSs for delivery of therapeutic drugs holds an enormous potential in next-generation theranostic platforms. Controllable, precise, and safe delivery of diagnostic biosensing devices and therapeutic agents to the target tissues, organs, or cells is an important determinant in developing advanced nanobiosensor-based theranostic platforms. Particularly, inspired by the comprehensive biological investigations on the red blood cells (RBCs), advanced strategies of RBC-mediated in vivo delivery have been developed rapidly and are currently in different stages of transforming from research and design to pre-clinical and clinical investigations. In this review, the RBC-mediated delivery of in vivo nanobiosensors for applications of bio-imaging at the single-cell level, advanced medical diagnostics, and analytical detection of biomolecules and cellular activities are presented. A comprehensive perspective of the technical framework of the state-of-the-art RBC-mediated delivery systems is explained in detail to inspire the design and implementation of advanced nanobiosensor-based theranostic platforms taking advantage of RBC-delivery modalities.

Nanoparticles Coated with Cell Membranes for Biomedical Applications

Simple Summary

Nanomedicine has developed a new technology based on nanoparticles for drug delivery coated with different cell membranes. Although they were originally developed to increase their blood circulation time and stability though the use of red blood cell membranes, the versatility of this technology has extended to membranes from different cell types, such as white blood cells, platelets, cancer cells, mesenchymal stem cells, and beta cells, among others. Therefore, this cellular diversity and its unique properties, together with the possibility of using a wide range of nanoparticles and different drug dosage forms, has opened a new area for the manufacture of nanoparticles, with many potential applications in the clinic.

Abstract

Nanoparticles designed for diagnosing and treating different diseases have impacted the scientific research in biomedicine, and are expected to revolutionize the clinic in the near future through a new area called nanomedicine. In the last few years, a new approach in this field has emerged: the use of cell membranes for coating nanoparticles in an attempt to mimic the ability of cells to interface and interact with physiological environments. Although such functions have been replicated through synthetic techniques, many research groups are now employing naturally derived cell membranes to coat different types of nanoparticles in an attempt to improve their performance for a wide range of applications. This review summarizes the literature on nanoparticles coated with cell membranes and, more importantly, aims at inspiring and encouraging new developments to this technology in the biomedical area.

Labeling and tracking cells with gold nanoparticles

Gold nanoparticles (AuNPs) have garnered much attention as contrast agents for computerized tomography (CT) because of their facile synthesis and surface functionalization, in addition to their significant X-ray attenuation and minimal cytotoxicity. Cell labeling using AuNPs and tracking of the labeled cells using CT has become a time-efficient and cost-effective method. Actively targeted AuNPs can enhance CT contrast and sensitivity, and further reduce the radiation dosage needed during CT imaging. In this review, we summarize the state-of-the-art use of AuNPs in CT for cell tracking, including the precautionary steps necessary for their use and the difficulty in translating the process into clinical use.

Roadmap for metal nanoparticles in radiation therapy: current status, translational challenges, and future directions

This roadmap outlines the potential roles of metallic nanoparticles (MNPs) in the field of radiation therapy. MNPs made up of a wide range of materials (from Titanium, Z = 22, to Bismuth, Z = 83) and a similarly wide spectrum of potential clinical applications, including diagnostic, therapeutic (radiation dose enhancers, hyperthermia inducers, drug delivery vehicles, vaccine adjuvants, photosensitizers, enhancers of immunotherapy) and theranostic (combining both diagnostic and therapeutic), are being fabricated and evaluated. This roadmap covers contributions from experts in these topics summarizing their view of the current status and challenges, as well as expected advancements in technology to address these challenges.

Construction of biomimetic silver nanoparticles in the treatment of lymphoma

Lymphoma is a well-known malignant tumor in the human body. Although many anticancer drugs have been developed to improve the survival rate of patients, about 40% of patients continue to be recurrent or refractory, a key issue needing remedy. Therefore, it is necessary to identify alternative treatments to reduce the disease's mortality. To this effect, a new type of anti-lymphoma nanocomplex FA@RBCm-AgNPs was prepared using AgNPs as the core of nanoparticles along with the targeting molecule folic acid inserted erythrocyte membrane as the shell. The biomimetic properties of red blood cell membrane (RBCm) endow F-RAN with good biocompatibility as well as the ability to evade clearance of the reticuloendothelial system. In addition, F-RAN was modified with folic acid to actively and selectively identify tumor cells. In vivo and in vitro experiments demonstrate that F-RAN can inhibit lymphoma cells and induce apoptosis of stem cells while promoting apoptosis of lymphoma with no obvious side effects. Hence, F-RAN may serve as a new treatment for lymphoma.

Hybrid red blood cell membrane coated porous silicon nanoparticles functionalized with cancer antigen induce depletion of T cells

Erythrocyte-based drug delivery systems have been investigated for their biocompatibility, long circulation time, and capability to transport cargo all around the body, thus presenting enormous potential in medical applications. In this study, we investigated hybrid nanoparticles consisting of nano-sized autologous or allogeneic red blood cell (RBC) membranes encapsulating porous silicon nanoparticles (PSi NPs). These NPs were functionalized with a model cancer antigen TRP2, which was either expressed on the surface of the RBCs by a cell membrane-mimicking block copolymer polydimethylsiloxane-b-poly-2-methyl-2-oxazoline, or attached on the PSi NPs, thus hidden within the encapsulation. When in the presence of peripheral blood immune cells, these NPs resulted in apoptotic cell death of T cells, where the NPs having TRP2 within the encapsulation led to a stronger T cell deletion. The deletion of the T cells did not change the relative proportion of CD4⁺ and cytotoxic CD8⁺ T cells. Overall, this work shows the combination of nano-sized RBCs, PSi, and antigenic peptides may have use in the treatment of autoimmune diseases.

We report a study on the effect of red blood cell membrane based cancer antigen-functionalized nanoparticles on peripheral blood T cells. These nanoparticles induce apoptosis of T cells and they may have use in treating autoimmune diseases.

Nanomedicine-based tumor photothermal therapy synergized immunotherapy

The emerging anti-tumor immunotherapy has made significant progress in clinical application. However, single immunotherapy is not effective for all anti-tumor treatments, owing to the low objective response rate and the risk of immune-related side effects. Meanwhile, photothermal therapy (PTT) has attracted significant attention because of its non-invasiveness, spatiotemporal controllability and small side effects. Combining PTT with immunotherapy overcomes the issue that single photothermal therapy cannot eradicate tumors with metastasis and recurrence. However, it improves the therapeutic effect of immunotherapy, as the photothermal therapy usually promotes release of tumor-related antigens, triggers immune response by the immunogenic cell death (ICD), thereby, endowing unique synergistic mechanisms for cancer therapy. This review summarizes recent research advances in utilizing nanomedicines for PTT in combination with immunotherapy to improve the outcome of cancer treatment. The strategies include immunogenic cell death, immune agonists and cancer vaccines, immune checkpoint blockades and tumor specific monoclonal antibodies, and small-molecule immune inhibitors. The combination of synergized PTT-immunotherapy with other therapeutic strategies is also discussed.

Tumor Exosome Mimicking Nanoparticles for Tumor Combinatorial Chemo-Photothermal Therapy

The development of biomimetic nanoparticles with functionalities of natural biomaterial remains a major challenge in cancer combination therapy. Herein, we developed a tumor-cell-derived exosome-camouflaged porous silicon nanoparticles (E-MSNs) as a drug delivery system for co-loading ICG and DOX (ID@E-MSNs), achieving the synergistic effects of chemotherapy and photothermal therapy against breast cancer. Compared with ID@MSNs, the biomimetic nanoparticles ID@E-MSNs can be effectively taken up by the tumor cell and enhance tumor accumulation with the help of the exosome membrane. ID@E-MSNs also retain the photothermal effect of ICG and cytotoxicity of DOX. Under 808 nm near infrared irradiation, ICG can produce hyperthermia to collapse E-MSNs nanovehicles, accelerate drug release, and induce tumor ablation, achieving effective chemo-photothermal therapy. In vivo results of 4T1 tumor-bearing BALB/c mice showed that ID@E-MSNs could accumulate tumor tissue and inhibit the growth and metastasis of tumor. Thus, tumor exosome-biomimetic nanoparticles indicate a proof-of-concept as a promising drug delivery system for efficient cancer combination therapy.

Gold nanoparticles change small extracellular vesicle attributes of mouse embryonic stem cells

Gold nanoparticles (AuNPs) have attracted considerable interest in suppressing tumor cell migration, while small extracellular vesicles (sEVs) play an essential role in tumor metastasis by shaping the tumor microenvironment. Understanding how AuNPs alter sEV attributes is critical in antitumor medication design. In this study, mouse embryonic stem cells (mESCs) were treated with three sizes of AuNPs (i.e. 5 nm AuNPs, 20 nm AuNPs, and 80 nm AuNPs) to obtain sEVs (i.e. sEV-5, sEV-20, and sEV-80), which were characterized from the biophysical and proteomic aspects. When compared with the control (sEV-ctrl), sEV-5 possessed relatively higher rigidity, and a differentially expressed protein profile. It attenuated 4T1 tumor cell proliferation and migration through inhibiting cofilin expression and extracellular regulated protein kinase (Erk) phosphorylation, which was opposite to the effect induced by sEV-ctrl. In contrast, sEV-20 and sEV-80 had negligible effects. This study revealed for the first time that AuNP-5 exposure changed the biophysical properties and cellular functions of mESC-derived sEVs, providing a promising strategy for designing AuNP-based antitumor medication.

Feasibility of Mechanical Extrusion to Coat Nanoparticles with Extracellular Vesicle Membranes

Biomimetic functionalization to confer stealth and targeting properties to nanoparticles is a field of intense study. Extracellular vesicles (EV), sub-micron delivery vehicles for intercellular communication, have unique characteristics for drug delivery. We investigated the top-down functionalization of gold nanoparticles with extracellular vesicle membranes, including both lipids and associated membrane proteins, through mechanical extrusion. EV surface-exposed membrane proteins were confirmed to help avoid unwanted elimination by macrophages, while improving autologous uptake. EV membrane morphology, protein composition and orientation were found to be unaffected by mechanical extrusion. We implemented complementary EV characterization methods, including transmission- and immune-electron microscopy, and nanoparticle tracking analysis, to verify membrane coating, size and zeta potential of the EV membrane-cloaked nanoparticles. While successful EV membrane coating of the gold nanoparticles resulted in lower macrophage uptake, low yield was found to be a significant downside of the extrusion approach. Our data incentivize more research to leverage EV membrane biomimicking as a unique drug delivery approach in the near future.

Unraveling Cell-Type-Specific Targeted Delivery of Membrane-Camouflaged Nanoparticles with Plasmonic Imaging

Cell-membrane-camouflaged nanoparticles (CMC-NPs) have been increasingly exploited to develop various therapeutic tools due to their high biocompatibility and cell-type-specific tumor-targeting properties. However, the molecular mechanism of CMC-NPs for homotypic targeting remains elusive. Here, we develop a plasmonic imaging method by coating gold nanoparticles (AuNPs) with cancer cell membranes and perform plasmonic imaging of the interactions between CMC-NPs and living cells at the single-cell level. Quantitative analysis of CMC-NPs in a different clustering status reveals that the presence of cell membranes on CMC-NPs results in a 7-fold increase in homotypic cell delivery and nearly 2 orders of magnitude acceleration of the intracellular agglomeration process. Significantly, we identify that integrin α_vβ₃, a cell surface receptor abundantly expressed in tumor cells, is critical for the selective cell recognition of CMC-NPs. We thus establish a single-cell plasmonic imaging platform for probing NP-cell interactions, which sheds new light on the therapeutic applications of CMC-NPs.

Medical micro/nanorobots in complex media

Medical micro/nanorobots have received tremendous attention over the past decades owing to their potential to be navigated into hard-to-reach tissues for a number of biomedical applications ranging from targeted drug/gene delivery, bio-isolation, detoxification, to nanosurgery. Despite the great promise, the majority of the past demonstrations are primarily under benchtop or in vitro conditions. Many developed micro/nanoscale propulsion mechanisms are based on the assumption of a homogeneous, Newtonian environment, while realistic biological environments are substantially more complex. Moving toward practical medical use, the field of micro/nanorobotics must overcome several major challenges including propulsion through complex media (such as blood, mucus, and vitreous) as well as deep tissue imaging and control in vivo. In this review article, we summarize the recent research efforts on investigating how various complexities in biological environments impact the propulsion of micro/nanoswimmers. We also highlight the emerging technological approaches to enhance the locomotion of micro/nanorobots in complex environments. The recent demonstrations of in vivo imaging, control and therapeutic medical applications of such micro/nanorobots are introduced. We envision that continuing materials and technological innovations through interdisciplinary collaborative efforts can bring us steps closer to the fantasy of "swallowing a surgeon".

Controlling timing and location in vaccines

Vaccines are one of the most powerful technologies supporting public health. The adaptive immune response induced by immunization arises following appropriate activation and differentiation of T and B cells in lymph nodes. Among many parameters impacting the resulting immune response, the presence of antigen and inflammatory cues for an appropriate temporal duration within the lymph nodes, and further within appropriate subcompartments of the lymph nodes– the right timing and location– play a critical role in shaping cellular and humoral immunity. Here we review recent advances in our understanding of how vaccine kinetics and biodistribution impact adaptive immunity, and the underlying immunological mechanisms that govern these responses. We discuss emerging approaches to engineer these properties for future vaccines, with a focus on subunit vaccines.

Metal-Organic Frameworks with Enhanced Photodynamic Therapy: Synthesis, Erythrocyte Membrane Camouflage, and Aptamer-Targeted Aggregation

Here, ferric oxide-loaded metal-organic framework (FeTCPP/Fe₂O₃ MOF) nanorice was designed and constructed by the liquid diffusion method. The introduction of iron metal nodes and the loading of Fe₂O₃ can effectively catalyze the Fenton reaction to produce hydroxyl radicals (^•OH) and overcome the hypoxic environment of tumor tissue by generating oxygen. The monodispersity and porosity of the porphyrin photosensitizers in the MOF structure exposed more active sites, which promoted energy exchange between porphyrin molecules and oxygen molecules for photodynamic therapy (PDT) treatment. Therefore, the generated hydroxyl radicals and singlet oxygen (¹O₂) can synergistically act on tumor cells to achieve the purpose of improving tumor therapy. Then the erythrocyte membrane was camouflaged to enhance blood circulation and tissue residence time in the body, and finally, the targeted molecule AS1411 aptamer was modified to achieve the high enrichment of MOF photosensitizers on a tumor domain. As a result, the MOF nanorice camouflaged by the erythrocyte membrane can effectively reduce side effects and improve the therapeutic effect of PDT and chemo-dynamic therapy (CDT). The study not only improved the efficacy of PDT and CDT in essence from the MOF nanorice but also used the camouflage method to further concentrate FeTCPP/Fe₂O₃ on the tumor sites, achieving the goal of multiple gains. These results will provide theoretical and practical directions for the development of tumor-targeted MOF nanomaterials.

Cell-derived biomimetic nanoparticles as a novel drug delivery system for atherosclerosis: predecessors and perspectives

Atherosclerosis is a key mechanism underlying the pathogenesis of cardiovascular disease, which is associated with high morbidity and mortality. In the field of precision medicine for the treatment of atherosclerosis, nanoparticle (NP)-mediated drug delivery systems have great potential, owing to their ability to release treatment locally. Cell-derived biomimetic NPs have attracted extensive attention at present due to their excellent targeting to atherosclerotic inflammatory sites, low immunogenicity and long blood circulation time. Here, we review the utility of cell-derived biomimetic NPs, including whole cells, cell membranes and extracellular vesicles, in the treatment of atherosclerosis.

Generation, purification and engineering of extracellular vesicles and their biomedical applications

Extracellular vesicles (EVs), derived from cell membranes, demonstrate the potential to be excellent therapeutics and drug carriers. Although EVs are promising, the process to develop high-quality and scalable EVs for their translation is demanding. Within this research, we analyzed the production of EVs, their purification and their post-bioengineering, and we also discussed the biomedical applications of EVs. We focus on the developments of methods in producing EVs including biological, physical, and chemical approaches. Furthermore, we discuss the challenges and the opportunities that arose when we translated EVs in clinic. With the advancements in nanotechnology and immunology, genetically engineering EVs is a new frontier in developing new therapeutics in order to tailor to individuals and different disease stages in treatments of cancer and inflammatory diseases.

Stealth Coating of Nanoparticles in Drug-Delivery Systems

Nanoparticles (NPs) have emerged as a powerful drug-delivery tool for cancer therapies to enhance the specificity of drug actions, while reducing the systemic side effects. Nonetheless, NPs interact massively with the surrounding physiological environments including plasma proteins upon administration into the bloodstream. Consequently, they are rapidly cleared from the blood circulation by the mononuclear phagocyte system (MPS) or complement system, resulting in a premature elimination that will cause the drug release at off-target sites. By grafting a stealth coating layer onto the surface of NPs, the blood circulation half-life of nanomaterials can be improved by escaping the recognition and clearance of the immune system. This review focuses on the basic concept underlying the stealth behavior of NPs by polymer coating, whereby the fundamental surface coating characteristics such as molecular weight, surface chain density as well as conformations of polymer chains are of utmost importance for efficient protection of NPs. In addition, the most commonly used stealth polymers such as poly(ethylene glycol) (PEG), poly(2-oxazoline) (POx), and poly(zwitterions) in developing long-circulating NPs for drug delivery are also thoroughly discussed. The biomimetic strategies, including the cell-membrane camouflaging technique and CD47 functionalization for the development of stealth nano-delivery systems, are highlighted in this review as well.

Homotypic cell membrane-cloaked biomimetic nanocarrier for the accurate photothermal-chemotherapy treatment of recurrent hepatocellular carcinoma

BACKGROUND

Tumor recurrence in patients after surgery severely reduces the survival rate of surgical patients. Targeting and killing recurrent tumor cells and tissues is extremely important for the cancer treatment.

RESULTS

Herein, we designed a nano-biomimetic photothermal-controlled drug-loading platform HepM-TSL with good targeting ability and immunocompatibility for the treatment of recurrent hepatocellular carcinoma. HepM-TSL can accurately target the recurrent tumor area with the aid of the cloaked homotypic cell membrane and release the chemotherapy drugs in a controlled manner. In vivo results have confirmed that HepM-TSL loaded with drugs and photosensitizer achieves the synergistic treatment of recurrent hepatocellular carcinoma with good therapeutic effect and slight side effects.

CONCLUSION

Accordingly, HepM-TSL provides a sound photothermal-chemotherapy synergistic strategy for the treatment of other recurrent cancers besides of recurrent hepatocellular carcinoma.

A Biomimetic Nanoparticle to "Lure and Kill" Phospholipase A2

Inhibition of phospholipase A2 (PLA2) has long been considered for treating various diseases associated with an elevated PLA2 activity. However, safe and effective PLA2 inhibitors remain unavailable. Herein, we report a biomimetic nanoparticle design that enables a "lure and kill" mechanism designed for PLA2 inhibition (denoted "L&K-NP"). The L&K-NPs are made of polymeric cores wrapped with modified red blood cell membrane with two inserted key components: melittin and oleyloxyethyl phosphorylcholine (OOPC). Melittin acts as a PLA2 attractant that works together with the membrane lipids to "lure" in-coming PLA2 for attack. Meanwhile, OOPC acts as inhibitor that "kills" PLA2 upon enzymatic attack. Both compounds are integrated into the L&K-NP structure, which voids toxicity associated with free molecules. In the study, L&K-NPs effectively inhibit PLA2-induced hemolysis. In mice administered with a lethal dose of venomous PLA2, L&K-NPs also inhibit hemolysis and confer a significant survival benefit. Furthermore, L&K-NPs show no obvious toxicity in mice. and the design provides a platform technology for a safe and effective anti-PLA2 approach.