Anisamide-Decorated pH-Sensitive Degradable Chimaeric Polymersomes Mediate Potent and Targeted Protein Delivery to Lung Cancer Cells

Rationalized landscape on protein-based cancer nanomedicine: Recent progress and challenges

The clinical advancement of protein-based nanomedicine has revolutionized medical professionals' perspectives on cancer therapy. Protein-based nanoparticles have been exploited as attractive vehicles for cancer nanomedicine due to their unique properties derived from naturally biomacromolecules with superior biocompatibility and pharmaceutical features. Furthermore, the successful translation of Abraxane™ (paclitaxel-based albumin nanoparticles) into clinical application opened a new avenue for protein-based cancer nanomedicine. In this mini-review article, we demonstrate the rational design and recent progress of protein-based nanoparticles along with their applications in cancer diagnosis and therapy from recent literature. The current challenges and hurdles that hinder clinical application of protein-based nanoparticles are highlighted. Finally, future perspectives for translating protein-based nanoparticles into clinic are identified.

Integration of caveolin-mediated cytosolic delivery and enzyme-responsive releasing of squalenoyl nanoparticles enhance the anti-cancer efficacy of chidamide in pancreatic cancer

We explored the potential of overcoming the dense interstitial barrier in pancreatic cancer treatment by enhancing the uptake of hydrophilic chemotherapeutic drugs. In this study, we synthesized the squalenoyl-chidamide prodrug (SQ-CHI), linking lipophilic squalene (SQ) with the hydrophilic antitumor drug chidamide (CHI) through a trypsin-responsive bond. Self-assembled nanoparticles with sigma receptor-bound aminoethyl anisamide (AEAA) modification, forming AEAA-PEG-SQ-CHI NPs (A-C NPs, size 116.6 ± 0.4 nm), and reference nanoparticles without AEAA modification, forming mPEG-SQ-CHI NPs (M-C NPs, size 88.3 ± 0.3 nm), were prepared. A-C NPs exhibited significantly higher in vitro CHI release (74.7 %) in 0.5 % trypsin medium compared to release (20.2 %) in medium without trypsin. In vitro cell uptake assays revealed 3.6 and 2.3times higher permeation of A-C NPs into tumorspheres of PSN-1/HPSC or CFPAC-1/HPSC, respectively, compared to M-C NPs. Following intraperitoneal administration to subcutaneous tumor-bearing nude mice, the A-C NPs group demonstrated significant anti-pancreatic cancer efficacy, inducing cancer cell apoptosis and inhibiting proliferation in vivo. Mechanistic studies revealed that AEAA surface modification on nanoparticles promoted intracellular uptake through caveolin-mediated endocytosis. This nanoparticle system presents a novel therapeutic approach for pancreatic cancer treatment, offering a delivery strategy to enhance efficacy through improved tumor permeation, trypsin-responsive drug release, and specific cell surface receptor-mediated intracellular uptake.

Surface-Modified Lyotropic Crystalline Nanoconstructs Bearing Doxorubicin and Buparvaquone Target Sigma Receptors through pH-Sensitive Charge Conversion to Improve Breast Cancer Therapy

In the current study, we aimed to develop lyotropic crystalline nanoconstructs (LCNs) based on poly(l-glutamic acid) (PLG) with a two-tier strategy. The first objective was to confer pH-responsive charge conversion properties to facilitate the delivery of both doxorubicin (DOX) and buparvaquone (BPQ) in combination (B + D@LCNs) to harness their synergistic effects. The second goal was to achieve targeted delivery to sigma receptors within the tumor tissues. To achieve this, we designed a pH-responsive charge conversion system using a polymer consisting of poly(ethylenimine), poly(l-lysine), and poly(l-glutamic acid) (PLG), which was then covalently coupled with methoxybenzamide (MBA) for potential sigma receptor targeting. The resulting B + D@LCNs were further modified by surface functionalization with PLG-MBA to confer both sigma receptor targeting and pH-responsive charge conversion properties. Our observations indicated that at physiological pH 7.4, P/B + D-MBA@LCNs exhibited a negative charge, while under acidic conditions (pH 5.5, characteristic of the tumor microenvironment), they acquired a positive charge. The particle size of P/B + D-MBA@LCNs was determined to be 168.23 ± 2.66 nm at pH 7.4 and 201.23 ± 1.46 nm at pH 5.5. The crystalline structure of the LCNs was confirmed through small-angle X-ray scattering (SAXS) diffraction patterns. Receptor-mediated endocytosis, facilitated by P/B + D-MBA@LCNs, was confirmed using confocal laser scanning microscopy and flow cytometry. The P/B + D-MBA@LCNs formulation demonstrated a higher rate of G2/M phase arrest (55.20%) compared to free B + D (37.50%) and induced mitochondrial depolarization (59.39%) to a greater extent than P/B + D@LCNs (45.66%). Pharmacokinetic analysis revealed significantly improved area under the curve (AUC) values for both DOX and BPQ when administered as P/B + D-MBA@LCNs, along with enhanced tumor localization. Tumor regression studies exhibited a substantial reduction in tumor size, with P/B + D-MBA@LCNs leading to 3.2- and 1.27-fold reductions compared to B + D and nontargeted P/B + D@LCNs groups, respectively. In summary, this two-tier strategy demonstrates substantial promise for the delivery of a drug combination through the prototype formulation. It offers a potential chemotherapeutic option by minimizing toxic effects on healthy cells while maximizing therapeutic efficacy.

Polymersome Membrane Engineering with Active Targeting or Controlled Permeability for Responsive Drug Delivery

Polymersomes have been extensively investigated for drug delivery as nanocarriers for two decades due to a series of advantages including high stability under physiological conditions, simultaneous encapsulation of hydrophilic and hydrophobic drugs inside inner cavities and membranes, respectively, and facile adjustment of membrane and surface properties, as well as controlled drug release through incorporation of stimuli-responsive components. Despite these features, polymersome nanocarriers frequently suffer from nontargeting delivery and poor membrane permeability. In recent years, polymersomes have been functionalized for more efficient drug delivery. The surface shells were explored to be modified with diverse active targeting groups to improve disease-targeting delivery. The membrane permeability of the polymersomes was adjusted by incorporation of the stimuli-responsive components for smart controlled transportation of the encapsulated drugs. Therefore, being the polymersome-biointerface, tailorable properties can be introduced by its carefully modulated engineering. This review elaborates on the role of polymersome membranes as a platform to incorporate versatile features. First, we discuss how surface functionalization facilitates the directional journey to the targeting sites toward specific diseases, cells, or intracellular organelles via active targeting. Moreover, recent advances in the past decade related to membrane permeability to control drug release are also summarized. We finally discuss future development to promote polymersomes as in vivo drug delivery nanocarriers.

Stimuli-Responsive Hydrogels for Protein Delivery

Proteins and peptides are potential therapeutic agents, but their physiochemical properties make their use as drug substances challenging. Hydrogels are hydrophilic polymeric networks that can swell and retain high amounts of water or biological fluids without being dissolved. Due to their biocompatibility, their porous structure, which enables the transport of various peptides and proteins, and their protective effect against degradation, hydrogels have gained prominence as ideal carriers for these molecules' delivery. Particularly, stimuli-responsive hydrogels exhibit physicochemical transitions in response to subtle modifications in the surrounding environment, leading to the controlled release of entrapped proteins or peptides. This review is focused on the application of these hydrogels in protein and peptide delivery, including a brief overview of therapeutic proteins and types of stimuli-responsive polymers.

Design strategy and research progress of multifunctional nanoparticles in lung cancer therapy

INTRODUCTION

Lung cancer is one of the cancer types with the highest mortality rate, exploring a more effective treatment modality that improves therapeutic efficacy while mitigating side effects is now an urgent requirement. Designing multifunctional nanoparticles can be used to overcome the limitations of drugs and conventional drug delivery systems. Nanotechnology has been widely researched, and through different needs, suitable nanocarriers can be selected to load anti-cancer drugs to improve the therapeutic effect. It is foreseeable that with the rapid development of nanotechnology, more and more lung cancer patients will benefit from nanotechnology. This paper reviews the merits of various multifunctional nanoparticles in the treatment of lung cancer to provide novel ideas for lung cancer treatment.

AREAS COVERED

This review focuses on summarizing various nanoparticles for targeted lung cancer therapy and their advantages and disadvantages, using nanoparticles loaded with anti-cancer drugs, delivered to lung cancer sites, enhancing drug half-life, improving anti-cancer drug efficacy and reducing side effects.

EXPERT OPINION

The delivery mode of nanoparticles with superior pharmacokinetic properties in the in vivo circulation enhances the half-life of the drug, and provides tissue-targeted selectivity and the ability to overcome biological barriers, bringing a revolution in the field of oncology.

Intelligent design of polymersomes for antibacterial and anticancer applications

Polymersomes (or polymer vesicles) have attracted much attention for biomedical applications in recent years because their lumen can be used for drug delivery and their coronas and membrane can be modified with a variety of functional groups. Thus, polymersomes are very suitable for improved antibacterial and anticancer therapy. This review mainly highlighted recent advances in the synthetic protocols and design principles of intelligent antibacterial and anticancer polymersomes. Antibacterial polymersomes are divided into three categories: polymersomes as antibiotic nanocarriers, intrinsically antibacterial polymersomes, and antibacterial polymersomes with supplementary means including photothermal and photodynamic therapy. Similarly, the anticancer polymersomes are divided into two categories: polymersomes-based delivery systems and anticancer polymersomes with supplementary means. In addition, the bilateral relationship between bacteria and cancer is addressed, since more and more evidences show that bacteria may cause cancer or promote cancer progression. Finally, prospective on next-generation antibacterial and anticancer polymersomes are discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.

A pH-responsive mesoporous silica nanoparticle-based drug delivery system for targeted breast cancer therapy

In order to make the drug specifically aggregate at the tumor site, we had developed a targeted drug delivery system based on pH responsive mesoporous silica nanoparticles. Mesoporous silica nanoparticles (MSN-COOH) were prepared and doxorubicin (DOX) was loaded into the pores of MSN-COOH, and then polyethyleneimine (PEI) and anisamide (AA) were modified on the surface of mesoporous silica, named DOX@MSN-PEI-AA(DMPA). DMPA specifically entered tumor cells through AA-mediated receptor endocytosis; PEI dissociated from the surface of the MSN in the acidic environment of cellular lysosomes/endosomes due to protonation of PEI, resulting in steady release of the encapsulated DOX from the pores of MSN in the cytoplasm of the target cells. In vitro and in vivo anti-tumor experiments and hemolytic experiments indicated that DMPA can accurately target breast cancer cells and show excellent safety at the same time, showing great potential for tumor therapy.

Synthesis of block copolymers used in polymersome fabrication: Application in drug delivery

Amphiphilic block copolymers are common materials used for the fabrication of various nanostructures with biomedical applications including nanocapsules, nanospheres, micelles and polymeric vesicles. According to the literature, polymersomes have several advantages compared to other nanostructures used as drug delivery systems comprising better stability, facile synthesis, prolonged circulation time, and passive/active targeting capability. Various types of nanoparticles are formed by varying the ratio of the hydrophobic/hydrophilic blocks. Changing hydrophobic/hydrophilic ratio of amphiphilic block copolymers has an impact on the structural characteristics of polymers such as changing molecular weight and surface functionalization of the block copolymer. Thus, polymerization strategies are an important factor that influences polymersomes quality. In this review, different polymerization strategies for the synthesis of block copolymers applied in polymersomes formation, are described.

Increased Protein Encapsulation in Polymersomes with Hydrophobic Membrane Anchoring Peptides in a Scalable Process

Hollow vesicles made from a single or double layer of block-copolymer molecules, called polymersomes, represent an important technological platform for new developments in nano-medicine and nano-biotechnology. A central aspect in creating functional polymersomes is their combination with proteins, especially through encapsulation in the inner cavity of the vesicles. When producing polymersomes by techniques such as film rehydration, significant proportions of the proteins used are trapped in the vesicle lumen, resulting in high encapsulation efficiencies. However, because of the difficulty of scaling up, such methods are limited to laboratory experiments and are not suitable for industrial scale production. Recently, we developed a scalable polymersome production process in stirred-tank reactors, but the statistical encapsulation of proteins resulted in fairly low encapsulation efficiencies of around 0.5%. To increase encapsulation in this process, proteins were genetically fused with hydrophobic membrane anchoring peptides. This resulted in encapsulation efficiencies of up to 25.68%. Since proteins are deposited on the outside and inside of the polymer membrane in this process, two methods for the targeted removal of protein domains by proteolysis with tobacco etch virus protease and intein splicing were evaluated. This study demonstrates the proof-of-principle for production of protein-functionalized polymersomes in a scalable process.

Recent Progress in Stimuli-Responsive Intelligent Nano Scale Drug Delivery Systems: A Special Focus Towards pH-Sensitive Systems

Stimuli-responsive nanocarriers are gaining much attention due to their versatile multifunctional activities, including disease diagnosis and treatment. Recently, clinical applications of nano-drug delivery systems for cancer treatment pose a challenge due to their limited cellular uptake, low bioavailability, poor targetability, stability issues, and unfavourable pharmacokinetics. To overcome these issues, researchers are focussing on stimuli-responsive systems. Nanocarriers elicit their role through endogenous (pH, temperature, enzyme, and redox) or exogenous (temperature, light, magnetic field, ultrasound) stimulus. These systems were designed to overcome the shortcomings such as non-specificity and toxicity associated with the conventional drug delivery systems. The pH variation between healthy cells and tumor microenvironment creates a platform for the generation of pH-sensitive nano delivery systems. Herein, we propose to present an overview of various internal and external stimuli-responsive behavior-based drug delivery systems. Herein, the present review will focus specifically on the significance of various pH-responsive nanomaterials such as polymeric nanoparticles, nano micelles, inorganic-based pH-sensitive drug delivery carriers such as calcium phosphate nanoparticles, and carbon dots in cancer treatment. Moreover, this review elaborates the recent findings on pH-based stimuli-responsive drug delivery systems with special emphasis on our reported stimuli-responsive systems for cancer treatment.

Combinatorial delivery of doxorubicin and acridine orange by gold core silica shell nanospheres functionalized with poly(ethylene glycol) and 4-methoxybenzamide for cancer targeted therapy

Combinatorial therapies based on the simultaneous administration of multiple drugs can lead to synergistic effects, increasing the efficacy of the cancer therapy. However, it is crucial to develop new delivery systems that can increase the drugs' therapeutic selectivity and efficacy. Gold core silica shell (AuMSS) nanoparticles present physicochemical properties that allow their simultaneous application as drug delivery and imaging agents. Herein, poly(ethylene glycol) was modified with 4-methoxybenzamide and 3-(triethoxysilyl)propyl isocyanate (TPANIS) to create a novel surface functionalization capable of improving the colloidal stability and specificity of AuMSS nanospheres towards cancer cells. Moreover, a dual drug combination based on Doxorubicin (DOX) and Acridine orange (AO) was characterized and administered using the AuMSS-TPANIS nanospheres. The obtained results show that the DOX:AO drug combination can mediate a synergistic therapeutic effect in both HeLa and MCF-7 cells, particularly at the 2:1, 1:1, and 1:2 ratios. Additionally, the TPANIS functionalization increased the AuMSS nanospheres colloidal stability and selectivity towards MCF-7 cancer cells (overexpressing sigma receptors). Such also resulted in an enhanced cytotoxic effect against MCF-7 cells when administering the DOX:AO drug combination with the AuMSS-TPANIS nanospheres. Overall, the obtained results confirm the therapeutic potential of the DOX:AO drug combination as well as the targeting capacity of AuMSS-TPANIS, supporting its application in the cancer-targeted combinatorial chemotherapy.

Au-siRNA@ aptamer nanocages as a high-efficiency drug and gene delivery system for targeted lung cancer therapy

BACKGROUND

Gene and chemical therapy has become one of the rising stars in the field of molecular medicine during the last two decades. However, there are still numerous challenges in the development of efficient, targeted, and safe delivery systems that can avoid siRNA degradation and reduce the toxicity and adverse effects of chemotherapy medicine.

RESULTS

In this paper, a highly efficient AS1411 aptamer modified, dsDNA and MMP-2 cleavable peptide-fabricated gold nanocage vehicle, which could load doxorubicin hydrochloride (DOX) and siRNAs to achieve a combination of tumor responsive genetic therapy, chemotherapy, and photothermal treatment is presented. Our results show that this combined treatment achieved targeted gene silencing and tumor inhibition. After nearly one month of treatment with DOX-loaded Au-siRNA-PAA-AS1411 nanoparticles with one dose every three days in mice, a synergistic effect promoting the eradication of long-lived tumors was observed along with an increased survival rate of mice. The combined genetic, chemotherapeutic, and photothermal treatment group exhibited more than 90% tumor inhibition ratio (tumor signal) and a ~ 67% survival rate compared with a 30% tumor inhibition ratio and a 0% survival rate in the passive genetic treatment group.

CONCLUSIONS

The development of nanocarriers with double-stranded DNA and MMP-2 cleavable peptides provides a new strategy for the combined delivery of gene and chemotherapy medicine. Au-siRNA-PAA-AS1411 exerts high anticancer activities on lung cancer, indicating immense potentials for clinical application.

Polypeptide Nanoparticles with pH-Sheddable PEGylation for Improved Drug Delivery

The variation of tumor microenvironments provides a tool for the construction of stimulus-responsive nanomedicines to enhance drug delivery efficacy. Herein, the assembly of drug-loaded polypeptide nanoparticles (NPs) with pH-sheddable modification of poly(ethylene glycol) (PEG) is prepared to enhance therapeutic efficiency. Poly(l-lysine) and poly(l-glutamic acid) were self-assembled to fabricate polypeptide NPs by electrostatic interactions, followed by PEGylation based on amidation reaction. The NP sizes can be controlled by tuning the molecular weight or the ratio of polypeptides. The PEG coating is cleavable at the tumor acid microenvironment to reverse the surface charge and reduce the NP size, which effectively enhances cell uptake. In addition, the presence of reducing reagent (e.g., glutathione) in cancer cells induces the drug (i.e., cisplatin) release from the polypeptide NPs and subsequently results in the cell toxicity. This reported method highlights the engineering of transformable polypeptide drug carriers, which provides a promising way for enhanced drug delivery efficacy.

Engineering Thermo-pH Dual Responsive Hydrogel for Enhanced Tumor Accumulation, Penetration, and Chemo-Protein Combination Therapy

Purpose

Combined chemotherapeutic drug and protein drug has been a widely employed strategy for tumor treatment. To realize both tumor accumulation and deep tumor penetration for drugs with different pharmacokinetics, we propose a structure-transformable, thermo-pH dual responsive co-delivery system to co-load granzyme B/docetaxel (GrB/DTX).

Methods

Thermo-sensitive hydrogels based on diblock copolymers (mPEG-b-PELG) were synthesized through ring opening polymerization. GrB/DTX mini micelles (GDM) was developed by co-loading these two drugs in pH-sensitive mini micelles, and the GDM-incorporated thermo-sensitive hydrogel (GDMH) was constructed. The thermo-induced gelation behavior of diblock copolymers and the physiochemical properties of GDMH were characterized. GDMH degradation and deep tumor penetration of released mini micelles were confirmed. The pH-sensitive disassembly and lysosomal escape abilities of released mini micelles were evaluated. In vitro cytotoxicity was studied using MTT assays and the in vivo antitumor efficacy study was evaluated in B16-bearing C57BL/6 mice.

Results

GDMH was gelatinized at body temperature and can be degraded by proteinase to release mini micelles. The mini micelles incorporated in GDMH can achieve deep tumor penetration and escape from lysosomes to release GrB and DTX. MTT results showed that maximum synergistic antitumor efficacy of GrB and DTX was observed at mass ratio of 1:100. Our in vivo antitumor efficacy study showed that GDMH inhibited tumor growth in the subcutaneous tumor model and in the post-surgical recurrence model.

Conclusion

The smart-designed transformable GDMH can facilitate tumor accumulation, deep tumor penetration, and rapid drug release to achieve synergistic chemo-protein therapy.

Polymer Nanocontainers for Intracellular Delivery

Carriers for intracellular delivery are required to overcome limitations of therapeutic agents such as low specificity, systemic toxicity, high clearance rate, and low therapeutic index. Nanocontainers comprised of an aqueous core and a polymer shell have received increasing attention because they readily combine stimuli response to improve intracellular payload release and surface modification to enhance selectivity towards the desired region of action. This Minireview summarizes the design and properties of polymer nanocontainers for intracellular delivery, classified according to the polymer architecture.

NIRF turn-on nanoparticles based on the tumor microenvironment for monitoring intracellular protein delivery

A dual responsive NIRF turn-on protein delivery system incorporating an NIRF turn-on probe and protein into one single nanoparticle has been constructed. It can be taken up efficiently by A549 cells, where protein release and NIRF recovery happen simultaneously in response to low pH and excessive H2O2. This work provides a novel system for monitoring intracellular protein delivery.

Novel Paclitaxel-Loaded Nanoparticles Based on Human H Chain Ferritin for Tumor-Targeted Delivery

Paclitaxel (PTX), an excellent chemotherapeutic antitumor drug, is widely used to treat patients with various cancers. However, its clinical applications are greatly restricted by poor solubility and lack of targeting. Herein, we applied natural human H chain ferritin (HFtn) nanocages that can bind to tumor cells via interacting with the human transferritin receptor 1 (TfR1) leading to its endocytosis as the PTX carrier for the targeted delivery. PTX molecules were encapsulated into HFtn cavity using disassembly/reassembly method through adjusting pH. According to the requirements of drugs suitable for clinical trials, HFtn can be easily purified in high yields with no ligand modification or property modulation. We demonstrated that PTX molecules were successfully encapsulated in the protein nanocages. The HFtn-PTX nanoparticles exhibited similar morphology and structural characteristics to the hollow cage and showed significant cytotoxicity in vitro than the naked PTX. Flow cytometry, confocal laser scanning microscopy, and in vivo imaging of MDA-MB-231 tumor demonstrated the HFtn-PTX nanoparticles targeting ability to tumor cells. Cell apoptosis assay showed that HFtn-PTX had similar apoptotic characteristics on MDA-MB-231 cells as that of the free PTX. HFtn-PTX nanoparticles have higher in vivo therapeutic efficacy and lower systemic toxicity. The BALB/c mice model also confirmed the effectiveness of the nanoparticles. Specifically targeting to tumors and solving the solubility issue of water-insoluble drugs thus alleviating the side effects, HFtn can be an efficient hydrophobic drug delivery nanocarrier for further applications in cancer therapy.

Rational Design of Nanocarriers for Intracellular Protein Delivery

Protein/antibody therapeutics have exhibited the advantages of high specificity and activity even at an extremely low concentration compared to small molecule drugs. However, they are accompanied by unfavorable physicochemical properties such as fragile tertiary structure, large molecular size, and poor penetration of the membrane, and thus the clinical use of protein drugs is hindered by inefficient delivery of proteins into the host cells. To overcome the challenges associated with protein therapeutics and enhance their biopharmaceutical applications, various protein-loaded nanocarriers with desired functions, such as lipid nanocapsules, polymeric nanoparticles, inorganic nanoparticles, and peptides, are developed. In this review, the different strategies for intracellular delivery of proteins are comprehensively summarized. Their designed routes, mechanisms of action, and potential therapeutics in live cells or in vivo are discussed in detail. Furthermore, the perspective on the new generation of delivery systems toward the emerging area of protein-based therapeutics is presented as well.

Acid-Triggered Nanoexpansion Polymeric Micelles for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) as a noninvasive and selective treatment technology has presented great potential in cancer prevention and precision medicine, but its therapeutic efficacy is still greatly inhibited by the limitations of photosensitizers (PSs) in the microenvironment such as the aggregation caused quenching (ACQ) of PSs. Herein, we proposed an "acid-triggered nanoexpansion" method to further reduce the aggregation of photosensitizers by constructing acetal-based polymeric micelles. A pH-responsive amphiphilic block copolymer, POEGMA-b-[PTTMA-co-PTPPC6MA] was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and self-assembled into spherical micelles. In the normal physiological environment, the micelles were stable and had good biocompatibility. Upon entry into the acidic microenvironment of the tumor, the acid-responsive hydrophobic 2, 4, 6-trimethoxybenzaldehyde in the micelles hydrolyzed and generated a hydrophilic diol moiety. Although the hydrophility of the micellar core was increased, the assembled structure of block copolymers was not dissociated but expanded. The responsive expansion of the micelles could allow the photosensitizers to well-disperse in the core, whereas more tumor-dissolved oxygen entered the micelles. This phenomenon could provide a better nanoenvironment for photosensitizers to reduce the ACQ of the photosensitizers, leading to more singlet oxygen (¹O₂) produced under the laser irradiation (650 nm). Both in vitro and in vivo studies have demonstrated that the remarkable photodynamic therapeutic efficacy of acid-responsive micelles could be realized. Thus, the acid-triggered nanoexpansion method might provide more possibilities to develop efficient platforms for treating cancers.

Nanocomposites as biomolecules delivery agents in nanomedicine

Nanoparticles (NPs) are atomic clusters of crystalline or amorphous structure that possess unique physical and chemical properties associated with a size range of between 1 and 100 nm. Their nano-sized dimensions, which are in the same range as those of vital biomolecules, such as antibodies, membrane receptors, nucleic acids, and proteins, allow them to interact with different structures within living organisms. Because of these features, numerous nanoparticles are used in medicine as delivery agents for biomolecules. However, off-target drug delivery can cause serious side effects to normal tissues and organs. Considering this issue, it is essential to develop bioengineering strategies to significantly reduce systemic toxicity and improve therapeutic effect. In contrast to passive delivery, nanosystems enable to obtain enhanced therapeutic efficacy, decrease the possibility of drug resistance, and reduce side effects of "conventional" therapy in cancers. The present review provides an overview of the most recent (mostly last 3 years) achievements related to different biomolecules used to enable targeting capabilities of highly diverse nanoparticles. These include monoclonal antibodies, receptor-specific peptides or proteins, deoxyribonucleic acids, ribonucleic acids, [DNA/RNA] aptamers, and small molecules such as folates, and even vitamins or carbohydrates.

Apolipoprotein E Peptide-Directed Chimeric Polymersomes Mediate an Ultrahigh-Efficiency Targeted Protein Therapy for Glioblastoma

The inability to cross the blood-brain barrier (BBB) prevents nearly all chemotherapeutics and biotherapeutics from the effective treatment of brain tumors, rendering few improvements in patient survival rates to date. Here, we report that apolipoprotein E peptide [ApoE, (LRKLRKRLL)₂C] specifically binds to low-density lipoprotein receptor members (LDLRs) and mediates superb BBB crossing and highly efficient glioblastoma (GBM)-targeted protein therapy in vivo. The in vitro BBB model studies reveal that ApoE induces 2.2-fold better penetration of the immortalized mouse brain endothelial cell line (bEnd.3) monolayer for chimeric polymersomes (CP) compared to Angiopep-2, the best-known BBB-crossing peptide used in clinical trials for GBM therapy. ApoE-installed CP (ApoE-CP) carrying saporin (SAP) displays a highly specific and potent antitumor effect toward U-87 MG cells with a low half-maximum inhibitory concentration of 14.2 nM SAP. Notably, ApoE-CP shows efficient BBB crossing as well as accumulation and penetration in orthotopic U-87 MG glioblastoma. The systemic administration of SAP-loaded ApoE-CP causes complete growth inhibition of orthotopic U-87 MG GBM without eliciting any observable adverse effects, affording markedly improved survival benefits. ApoE peptide provides an ultrahigh-efficiency targeting strategy for GBM therapy.

Granzyme B-loaded, cell-selective penetrating and reduction-responsive polymersomes effectively inhibit progression of orthotopic human lung tumor in vivo

The clinical use of protein therapeutics with intracellular targets is hampered by its in vivo fragility and low cell permeability. Here, we report that cell-selective penetrating and reduction-responsive polymersomes (CPRPs) mediate high-efficiency targeted delivery of granzyme B (GrB) to orthotopic human lung tumor in vivo. Model protein studies using FITC-labeled cytochrome C (FITC-CC) revealed efficient and high protein loading up to 17.2 wt% for CPRPs. FITC-CC-loaded CPRPs exhibited a small size of 82-90 nm, reduction-responsive protein release, as well as greatly enhanced internalization and cytoplasmic protein release in A549 lung cancer cells compared with the non-targeted FITC-CC-loaded RPs control. GrB-loaded CPRPs showed a high potency toward A549 lung cancer cells with a half maximal inhibitory concentration (IC₅₀) of 20.7 nM. Under the same condition, free GrB was essentially non-toxic. Importantly, installing cell-selective penetrating peptide did not alter the circulation time but did enhance tumor accumulation of RPs. Orthotopic A549-Luc lung tumor-bearing nude mice administered with GrB-loaded CPRPs at a dosage of 2.88 nmol GrB equiv./kg showed complete tumor growth inhibition with little body weight loss throughout the treatment period, resulting in significantly improved survival rate over the non-targeted and non-treated controls. These cell-selective penetrating and reduction-responsive polymersomes provide a targeted protein therapy for cancers.

Protein Nanotherapeutics as an Emerging Modality for Cancer Therapy

Protein drugs are a unique and versatile class of biotherapeutics that have not only high biological activity but also superb specificity. This rapidly evolving biotechnology has rendered it possible to produce various proteins in a large scale and reproducible way. Many proteins have demonstrated striking anticancer activities and have emerged as advanced alternatives to cytotoxic chemotherapeutic agents for cancer therapy. The clinical translation of anticancer proteins with intracellular targets is, nevertheless, severely hindered by their fast degradation in vivo, poor cell penetration, and inefficient intracellular transportation. The past few years have witnessed tremendous effort and progress in developing polymeric protein delivery nanosystems, ranging from nanoparticles, nanocapsules, nanogels, micelles, to polymersomes, for the treatment of different tumors such as lung tumors, breast tumors, ovarian cancers, and glioblastoma. These proof-of-concept studies point out that protein nanotherapeutics, with rationally designed nanovehicles, are able to overcome the extracellular barriers, cell membrane barriers, and intracellular barriers, and systemically deliver proteins into targeted cancer cells, resulting in effective cancer protein therapy. Protein nanotherapeutics appear to be a novel modality for safe and efficient cancer treatment.

A Self-Targeting, Dual ROS/pH-Responsive Apoferritin Nanocage for Spatiotemporally Controlled Drug Delivery to Breast Cancer

In this study, an intelligent pH and ROS dual-responsive drug delivery system based on an apoferritin (AFt) nanocage was prepared. This therapeutic system can specifically self-target 4T1 breast cancer cells by exploiting L-apoferritin receptor SCARA 5, avoiding the nonspecific binding or aggregation of nanoparticles due to the chemical functionalization for targeting. The characteristics of AFt were utilized for the simultaneous delivery of anticancer drug doxorubicin (DOX) and photosensitizer rose bengal (RB). RB exhibited efficient reactive oxygen species (ROS) generation, which can be applied to photodynamic therapy. Meanwhile, the AFt nanocage was prone to undergoing peptide backbone cleavage when oxidized by ROS. Therefore, by combining the intrinsic pH-responsive property of AFt, the dual ROS/pH-responsive system was developed. The time and location of drug release can be controlled by the combination of internal and external stimulus, which avoids the incomplete drug release under single stimulus response. The drug release rate increased significantly (from 26.1% to 92.0%) under low-pH condition (pH 5.0) and laser irradiation. More DOX from AFt entered the nucleus and killed the tumor cells, and the cell inhibition rate was up to ∼83% (DOX concentration: 5 μg/mL) after 48 h incubation. In addition, the biodistribution and the in vivo antitumor efficacy (within 14 d treatment) of the nanosystem were investigated in 4T1 breast cancer BALB/c mice. The results indicated that the system is a promising therapeutic agent involving ROS/pH dual response, self-targeting, and chemo-photodynamic therapy.

Asymmetrical Polymer Vesicles for Drug delivery and Other Applications

Scientists have been attracted by polymersomes as versatile drug delivery systems since the last two decades. Polymersomes have the potential to be versatile drug delivery systems because of their tunable membrane formulations, stabilities in vivo, various physicochemical properties, controlled release mechanisms, targeting abilities, and capacities to encapsulate a wide range of drugs and other molecules. Asymmetrical polymersomes are nano- to micro-sized polymeric capsules with asymmetrical membranes, which means, they have different outer and inner coronas so that they can exhibit better endocytosis rate and endosomal escape ability than other polymeric systems with symmetrical membranes. Hence, asymmetrical polymersomes are highly promising as self-assembled nano-delivery systems in the future for in vivo therapeutics delivery and diagnostic imaging applications. In this review, we prepared a summary about recent research progresses of asymmetrical polymersomes in the following aspects: synthesis, preparation, applications in drug delivery and others.

Targeting Nanocarriers with Anisamide: Fact or Artifact?

Encapsulating chemotherapeutics in nanoparticles can reduce the side effects of intravenous administration and improve their antitumor efficacy. Additionally, surface decoration of the nanocarriers with tumor-targeting ligands may enhance their specificity for cancer cells overexpressing the corresponding ligand-binding counterpart. The focus here is on anisamide, a low-molecular-weight benzamide derivative used as a tumor-directing moiety in functionalized nanosystems, based on its alleged interaction with Sigma receptors. The scintigraphic agents that initially inspired the use of anisamide for tumor targeting are described, and the published anisamide-tethered nanocarrier formulations are reviewed, together with a critical overview of the ligand's tumor-targeting properties. Moreover, anisamide's putative but dubious cellular target, the Sigma-1 receptor, is discussed with regard to its subcellular localization and implications in cancer. Data from in vivo studies reveal that the effect of anisamide on the antitumor efficacy of the decorated nanosystems varies considerably among the published reports. Together with the evidence questioning the interaction of anisamide with the Sigma receptors, the variability of anisamide's effect on the tumor deposition and the antitumor efficacy of the decorated drug carriers calls into question the extent of the ligand's tumor-targeting effect. Further research is necessary to elucidate the ligand's utility in tumor targeting.

Doxorubicin and resveratrol co-delivery nanoparticle to overcome doxorubicin resistance

With the extensive application of doxorubicin (DOX), DOX resistance has become one of the main obstacles to the effective treatment of breast cancer. In this paper, DOX and resveratrol (RES) were co-encapsulated in a modified PLGA nanoparticle (NPS) to overcome the DOX resistance. CLSM results indicated that DOX and RES were simultaneously delivered into the nucleus of DOX-resistant human breast cancer cells by DOX/RES-loaded NPS. Consequently, DOX/RES-loaded NPS showed significant cytotoxicity on MDA-MB-231/ADR cells and MCF-7/ADR cells. Furthermore, DOX/RES-loaded NPS could overcome DOX resistance by inhibiting the expression of drug resistance-related protein such as P-gp, MRP-1 and BCRP, and induce apoptosis through down-regulating the expression of NF-κB and BCL-2. In tumor-bearing mice, DOX/RES-loaded NPS mainly delivered DOX and RES to tumor tissue. Compared with free DOX, DOX/RES-loaded NPS significantly inhibited the DOX-resistant tumor growth in tumor-bearing mice without causing significant systemic toxicity. In a word, DOX/RES-loaded NPS could overcome the DOX resistance and had the potential in the treatment of DOX-resistant breast cancer.

Efficient and Targeted Suppression of Human Lung Tumor Xenografts in Mice with Methotrexate Sodium Encapsulated in All-Function-in-One Chimeric Polymersomes

Anisamide-functionalized reversibly crosslinked chimeric polymersomes emerge as an "all-function-in-one" nanoplatform for efficient loading and targeted delivery of methotrexate disodium, a potent water-soluble anticancer drug, to sigma receptor overexpressing H460 nonsmall lung cancer xenografts in vivo, leading to markedly improved tumor-growth inhibition and survival rate and depleted adverse effects as compared to the clinically used formulation (Trexall).

Redox-Sensitive and Intrinsically Fluorescent Photoclick Hyaluronic Acid Nanogels for Traceable and Targeted Delivery of Cytochrome c to Breast Tumor in Mice

In spite of their high specificity and potency, few protein therapeutics are applied in clinical cancer therapy owing to a lack of safe and efficacious delivery systems. Here, we report that redox-sensitive and intrinsically fluorescent photoclick hyaluronic acid nanogels (HA-NGs) show highly efficient loading and breast tumor-targeted delivery of cytochrome c (CC). HA-NGs were obtained from hyaluronic acid-graft-oligo(ethylene glycol)-tetrazole (HA-OEG-Tet) via inverse nanoprecipitation and catalyst-free photoclick cross-linking with l-cystine dimethacrylamide (MA-Cys-MA). HA-NGs exhibited a superb CC loading content of up to 40.6 wt %, intrinsic fluorescence (λem = 510 nm), and a small size of ca. 170 nm. Notably, CC-loaded nanogels (CC-NGs) showed a fast glutathione-responsive protein release behavior. Importantly, released CC maintained its bioactivity. MTT assays revealed that CC-NGs were highly potent with a low IC50 of 3.07 μM to CD44+ MCF-7 human breast tumor cells. Confocal microscopy observed efficient and selective internalization of fluorescent HA-NGs into MCF-7 cells. Interestingly, HA-NGs exhibited also effective breast tumor penetration. The therapeutic results demonstrated that CC-NGs effectively inhibited the growth of MCF-7 breast tumor xenografts at a particularly low dose of 80 or 160 nmol CC equiv./kg. Moreover, CC-NGs did not cause any change in mice body weight, corroborating their low systemic side effects. Redox-sensitive and intrinsically fluorescent photoclick hyaluronic acid nanogels have appeared as a "smart" protein delivery nanoplatform enabling safe, efficacious, traceable, and targeted cancer protein therapy in vivo.