pH responsive micelle self-assembled from a new amphiphilic peptide as anti-tumor drug carrier

Engineering disease analyte response in peptide self-assembly

A need to enhance the precision and specificity of therapeutic nanocarriers inspires the development of advanced nanomaterials capable of sensing and responding to disease-related cues. Self-assembled peptides offer a promising nanocarrier platform with versatile use to create precisely defined nanoscale materials. Disease-relevant cues can range from large biomolecules, such as enzymes, to ubiquitous small molecules with varying concentrations in healthy versus diseased states. Notably, pH changes (i.e., H+ concentration), redox species (e.g., H2O2), and glucose levels are significant spatial and/or temporal indicators of therapeutic need. Self-assembled peptides respond to these cues by altering their solubility, modulating electrostatic interactions, or facilitating chemical transformations through dynamic or labile bonds. This review explores the design and construction of therapeutic nanocarriers using self-assembled peptides, focusing on how peptide sequence engineering along with the inclusion of non-peptidic components can link the assembly state of these nanocarriers to the presence of disease-relevant small molecules.

Self-Assembled Peptide with Morphological Structure for Bioapplication

Peptide materials, such as self-assembled peptide materials, are very important biomaterials. Driven by multiple interaction forces, peptide molecules can self-assemble into a variety of different macroscopic forms with different properties and functions. In recent years, the research on self-assembled peptides has made great progress from laboratory design to clinical application. This review focuses on the different morphologies, including nanoparticles, nanovesicles, nanotubes, nanofibers, and others, formed by self-assembled peptide. The mechanisms and applications of the morphology transformation are also discussed in this paper, and the future direction of self-assembled nanomaterials is envisioned.

A methodological approach by capillary electrophoresis coupled to mass spectrometry via electrospray interface for the characterization of short synthetic peptides towards the conception of self-assembled nanotheranostic agents

Nanostructures formed by the self-assembling peptide building blocks are attractive materials for the design of theranostic objects due to their intrinsic biocompatibility, accessible surface chemistry as well as cavitary morphology. Short peptide synthesis and modification are straightforward and give access to a great diversity of sequences, making them very versatile building blocks allowing for the design of thoroughly controlled self-assembled nanostructures. In this work, we developed a new CE-DAD-ESI-MS method to characterize short synthetic amphiphilic peptides in terms of exact sequence and purity level in the low 0.1 mg.mL-1 range, without sample treatment. This study was conducted using a model sequence, described to have pH sensitive self-assembling property. Peptide samples obtained from different synthesis processes (batch or flow, purified or not) were thus separated by capillary zone electrophoresis (CZE). The associated dual UV and MS detection mode allowed to evidence the exact sequence together with the presence of impurities, identified as truncated or non-deprotected sequences, and to quantify their relative proportion in the peptide mixture. Our results demonstrate that the developed CE-DAD-ESI-MS method could be directly applied to the characterization of crude synthetic peptide products, in parallel with the optimization of peptide synthetic pathway to obtain controlled sequences with high synthetic yield and purity, which is crucial for further design of robust peptide based self-assembled nanoarchitectures.

An ultra pH-responsive peptide nanocarrier for cancer gene therapy

The tumor microenvironment is a very complex and dynamic ecosystem. Although a variety of pH-responsive peptides have been reported to deliver nucleic acid drugs for cancer treatment, these responses typically only target the acidic microenvironment of the tumor or the lysosome, and the carrier suffers from issues such as low transfection efficiency and poor lysosomal escape within the cell. To address this problem, we have developed an ultra pH-responsive peptide nanocarrier that can efficiently deliver siRNA, pDNA, and mRNA into cancer cells by performing progressive dynamic assembly in response to pH changes in the acidic tumor microenvironment (pH 6.5-6.8) and the acidic intracellular lysosomal environment (pH 5.0-6.0). The maximum transfection efficiency was 87.1% for pDNA and 74.9% for mRNA, which is higher than that of peptide-based nanocarrier reported to date. In addition, the targeting sequence on the surface allows the peptide@siRNA complex to efficiently enter cancer cells, causing 96% of cancer cell mortality. The carrier has high biocompatibility and low cytotoxicity, making it highly promising for application in immunotherapy and gene therapy of tumors.

Naphthyl-Poly(S-((2-carboxyethyl)thio)-l-cysteine) Peptide Amphiphiles with Different Degrees of Polymerization: Synthesis, Self-Assembly, pH/Reduction-Triggered Drug Release, and Cytotoxicity

Four peptide amphiphiles (PA1-4) with different degrees of polymerization (DP = 40, 15, 10, and 6) were synthesized by Fuchs-Farthing and ring-opening polymerization followed by post-polymerization modification, as fully characterized by ¹H NMR, FT-IR, gel permeation chromatography, and circular dichroism (CD) spectroscopy. It was found that PAs could self-assemble to form regular spherical micelles in low-concentration (about 1 mg/mL) aqueous solution, which had different contents of secondary structures and mainly adopted random coil conformations. The water solubility of PAs increases with the increase of DP, the polypeptide chain stretches randomly in water, the β-sheets decrease, and the random coil conformations dominate. When the pH of PA solution decreases or increases, intramolecular hydrogen bonds break, and molecular chains stretch, leading to a decrease of α-helix, turn conformations, and an increase of β-sheets. Meanwhile, the particle size of micelles increases. At around 0.4 mg/mL, the hemolysis ability of PA2 is negligible at pH 7.4 and 6.5 and about 33% at pH 5.5. Cisplatin (CDDP) was linked to micelles by coordination bonds to explore their potential as drug carriers, exhibiting controlled pH and reduction in dual drug release effects. MTT assay showed that the HeLa cell viability was 78% when cultured in the 13.5 μg/mL PA2 blank micelles for 2 days, while the cell viability was 60% in the CDDP-loaded micelles. Furthermore, a high concentration of PA2 (about 100 mg/mL) could self-assemble into a fibrous hydrogel at pH 5.5, which self-healed 2 h after incision and self-degraded 71% within 14 days. The CDDP-loaded fiber hydrogel exhibited a sustained release effect similar to the CDDP-loaded micelles. The cytotoxicity of CDDP-loaded fibers at 48 h was detected to be the same as that of the same amount of CDDP, and the cell viability was 7%. Therefore, we provide a new strategy for the synthesis of amphiphilic peptides with potential applications in nano-drug carriers and cancer therapy.

pH-Responsive Self-Assembling Peptide-Based Biomaterials: Designs and Applications

Stimuli-responsive peptide-based biomaterials are increasingly gaining interest for various specific and targeted treatments, including drug delivery and tissue engineering. Among all stimuli, pH can be especially useful because endogenous pH changes are often associated with abnormal microenvironments. pH-Responsive amino acids and organic linkers can be easily incorporated into peptides that self-assemble into various nanostructures. Thus, these largely biocompatible and easily tunable platforms are ideal candidates for drug release and as fibrous materials capable of mimicking the native extracellular matrix. In this review, we highlight common design motifs and mechanisms of pH-responsiveness in self-assembling peptide-based biomaterials, focusing on recent advances of these biomaterials applied in drug delivery and tissue engineering. Finally, we suggest future challenges and areas for potential development in pH-responsive self-assembling peptide-based biomaterials.

Self-assembly and disassembly mechanisms of biomimetic peptides: Molecular dynamics simulation and experimental measurement

Drug-loaded pH-responsive nanoparticles are potential drug carriers in nanotherapeutics delivery because they can remain stable in normal tissues but can disassemble and release drug molecules in tumors. In this study, the mechanisms of self-assembly and disassembly were investigated by analyzing the characteristics of three kinds of biomimetic peptides with different components and sequences. The structural parameters and energy changes during self-assembly and disassembly were calculated by molecular dynamics simulation. Transmission electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy were used to observe morphological changes and measure the strength of hydrophobic and hydrophilic interactions between peptides. Results show that the hydrophobic and hydrophilic interactions play crucial roles in the self-assembly and disassembly processes of peptides. The structure of the peptide clusters after self-assembly became tighter as the difference between hydrophobic and hydrophilic interactions increased, whereas a decrease in this difference led to the increased disassembly of the peptides. In general, polyethylene glycol chain modification was necessary in disassembly, and peptides with straight structures had stronger disassembly ability than that with branched structures with the same components. The morphology of peptide clusters can be controlled under different pH values by changing the composition and structure of the peptides for enhanced drug retention and sustained release.

Vasoactive Intestinal Peptide Amphiphile Micelle Chemical Structure and Hydrophobic Domain Influence Immunomodulatory Potentiation

Vasoactive intestinal peptide (VIP) is a neuropeptide capable of downregulating innate immune responses in antigen presenting cells (APCs) by suppressing their pro-inflammatory cytokine secretion and cell surface marker expression. Though VIP's bioactivity could possibly be leveraged as a treatment for transplant tolerance, drug delivery innovation is required to overcome its intrinsically limited cellular delivery capacity. One option is to employ peptide amphiphiles (PAs) which are lipidated peptides capable of self-assembling into micelles in water that can enhance cellular association. With this approach in mind, a series of triblock VIP amphiphiles (VIPAs) has been synthesized to explore the influence of block arrangement and hydrophobicity on micelle biocompatibility and bioactivity. VIPA formulation has been found to influence the shape, size, and surface charge of VIPA micelles (VIPAMs) as well as their cytotoxicity and immunomodulatory effects. Specifically, the enclosed work provides strong evidence that cylindrical VIPAMs with aspect ratios of 1.5-150 and moderate positive surface charge are able to potentiate the bioactivity of VIP limiting TNF-α secretion and MHC II and CD86 surface expression on APCs. With these criteria, we have identified PalmK-(EK)₄-VIP as our lead formulation, which showed comparable or enhanced anti-inflammatory effects relative to the unmodified VIP at all dosages evaluated. Additionally, the relationships between peptide block location and lipid block size provide further information on the chemical structure-function relationships of PA micelles for the delivery of VIP as well as potentially for other peptides more broadly.

Supramolecular peptide nano-assemblies for cancer diagnosis and therapy: from molecular design to material synthesis and function-specific applications

Peptide molecule has high bioactivity, good biocompatibility, and excellent biodegradability. In addition, it has adjustable amino acid structure and sequence, which can be flexible designed and tailored to form supramolecular nano-assemblies with specific biomimicking, recognition, and targeting properties via molecular self-assembly. These unique properties of peptide nano-assemblies made it possible for utilizing them for biomedical and tissue engineering applications. In this review, we summarize recent progress on the motif design, self-assembly synthesis, and functional tailoring of peptide nano-assemblies for both cancer diagnosis and therapy. For this aim, firstly we demonstrate the methodologies on the synthesis of various functional pure and hybrid peptide nano-assemblies, by which the structural and functional tailoring of peptide nano-assemblies are introduced and discussed in detail. Secondly, we present the applications of peptide nano-assemblies for cancer diagnosis applications, including optical and magnetic imaging as well as biosensing of cancer cells. Thirdly, the design of peptide nano-assemblies for enzyme-mediated killing, chemo-therapy, photothermal therapy, and multi-therapy of cancer cells are introduced. Finally, the challenges and perspectives in this promising topic are discussed. This work will be useful for readers to understand the methodologies on peptide design and functional tailoring for highly effective, specific, and targeted diagnosis and therapy of cancers, and at the same time it will promote the development of cancer diagnosis and therapy by linking those knowledges in biological science, nanotechnology, biomedicine, tissue engineering, and analytical science.

Peptide-Assisted Nucleic Acid Delivery Systems on the Rise

Concerns associated with nanocarriers' therapeutic efficacy and side effects have led to the development of strategies to advance them into targeted and responsive delivery systems. Owing to their bioactivity and biocompatibility, peptides play a key role in these strategies and, thus, have been extensively studied in nanomedicine. Peptide-based nanocarriers, in particular, have burgeoned with advances in purely peptidic structures and in combinations of peptides, both native and modified, with polymers, lipids, and inorganic nanoparticles. In this review, we summarize advances on peptides promoting gene delivery systems. The efficacy of nucleic acid therapies largely depends on cell internalization and the delivery to subcellular organelles. Hence, the review focuses on nanocarriers where peptides are pivotal in ferrying nucleic acids to their site of action, with a special emphasis on peptides that assist anionic, water-soluble nucleic acids in crossing the membrane barriers they encounter on their way to efficient function. In a second part, we address how peptides advance nanoassembly delivery tools, such that they navigate delivery barriers and release their nucleic acid cargo at specific sites in a controlled fashion.

Metal Binding Antimicrobial Peptides in Nanoparticle Bio-functionalization: New Heights in Drug Delivery and Therapy

Peptides are considered very important due to the diversity expressed through their amino acid sequence, structure variation, large spectrum, and their essential role in biological systems. Antimicrobial peptides (AMPs) emerged as a potent tool in therapy owing to their antimicrobial properties but also their ability to trespass the membranes, specificity, and low toxicity. They comprise a variety of peptides from which specific amino acid-rich peptides are of interest to the current review due to their features in metal interaction and cell penetration. Histidine-rich peptides such as Histatins belong to the metal binding salivary residing peptides with efficient antibacterial, antifungal, and wound-healing activities. Furthermore, their ability to activate in acidic environment attracted the attention to their potential in therapy. The current review covers the current knowledge about AMPs and critically assess the potential of associating with metal ions both structurally and functionally. This review provides interesting hints for the advantages provided by AMPs and metal ions in biomedicine, making use of their direct properties in brain diseases therapy or in the creation of new bio-functionalized nanoparticles for cancer diagnosis and treatment.

Novel Descriptors Derived from the Aggregation Propensity of Di- and Tripeptides Can Predict the Critical Aggregation Concentration of Longer Peptides

Self-assembling amphiphilic peptides have recently received special attention in medicine. Nonetheless, testing the myriad of combinations generated from at least 20 coded and several hundreds of noncoded amino acids to obtain candidate sequences for each application, if possible, is time-consuming and expensive. Therefore, rapid and accurate approaches are needed to select candidates from countless combinations. In the current study, we examined three conventional descriptor sets along with a novel descriptor set derived from the simulated aggregation propensity of di- and tripeptides to model the critical aggregation concentration (CAC) of amphiphilic peptides. In contrast to the conventional descriptors, the radial kernel model derived from the novel descriptor set accurately predicted the critical aggregation concentration of the test set with a residual standard error of 0.10. The importance of aromatic side chains, as well as neighboring amino acids in the self-assembly, was emphasized by analysis of the influential descriptors. The addition of very long peptides (70-100 residues) to the data set decreased the model accuracy and changed the influential descriptors. The developed model can be used to predict the CAC of self-assembling amphiphilic peptides and also to derive rules to apply in designing novel amphiphilic peptides with desired properties.

De novosynthesis of pH-responsive, self-assembled, and targeted polypeptide nano-micelles for enhanced delivery of doxorubicin

Doxorubicin (DOX) is a commonly used anticancer drug, but it is inefficient as a therapeutic due to a lack of targeting. Peptide-tuned self-assembly of DOX offers a strategy to improve targeting for greater efficacy. In this work, we designed and prepared an amphiphilic tumor cell-targeting peptide, P14 (AAAAFFFHHHGRGD), able to encapsulate DOX by self-assembly to form tumor cell-targeting and pH-sensitive nano-micelles. The results showed a critical P14-micelle concentration of 1.758 mg l^-1and an average particle size of micelles of 121.64 nm, with entrapment and drug-loading efficiencies of 28.02% ± 1.35% and 12.06% ± 0.59%, respectively. The prepared micelles can release 73.52 ± 1.27% DOX within 24 h in pH 4.5 medium, and the drug cumulative release profile of micelles can be described by the first-order model. Compared with free DOX, the micelles exhibited an increased ability to inhibit tumor cell growth and cause tumor apoptosisin vitro, with IC₅₀values of DOX and P14-DOX micelles against human breast cancer cells (MCF-7) of 0.91 ± 0.07 and 0.75 ± 0.06μg ml^-1, respectively, and cellular apoptotic rates of DOX and P14-DOX micelles of 70.3% and 42.4%, respectively. Cellular uptake experiments revealed high concentrations of micelles around and inside MCF-7 cells, demonstrating that micelles can target tumor cells. These results indicate the excellent potential for the application of this amphiphilic peptide as a carrier for small-molecule drugs and suggest a strategy for the design of effective anti-tumor drugs.

pH-triggered morphological change in a self-assembling amphiphilic peptide used as an antitumor drug carrier

The geometry of nanoparticles plays an important role in the process of drug encapsulation and release. In this study, an acid-responsive amphiphilic polypeptide consisting of lysine and leucine was prepared. In neutral media, the amphiphilic peptide L₆K₄ self-assembled to form spherical nanoparticles and encapsulated fat-soluble antitumor drugs. The intratumoral accumulation of the drug-loaded nanoparticles was improved in HeLa cells compared with normal cells. Compared to a neutral environment, increasingly acidic solutions changed the secondary structure of the peptide. In addition, the drug-loaded nanoparticles expanded and decomposed, rapidly releasing the poorly soluble antitumor drug doxorubicin (DOX). In addition, the amphiphilic peptide L₆K₄ had antitumor properties, and the antitumor performance of the combination of L₆K₄ and DOX was better than that of free DOX. Our results indicate that the use of acid responsiveness to induce geometric changes in drug-loaded peptide nanoparticles could be a promising strategy for antitumor drug delivery.

Plasma Amine Oxidase-Induced Nanoparticle-to-Nanofiber Geometric Transformation of an Amphiphilic Peptide for Drug Encapsulation and Enhanced Bactericidal Activity

Patients with cancer have reduced immune function and are susceptible to bacterial infection after surgery, chemotherapy, or radiotherapy. Spherical nanoparticles formed by the self-assembled peptide V₆K₃ can be used as carriers for poorly soluble antitumor drugs to effectively deliver drugs into tumor cells. V₆K₃ was designed to achieve nanoparticle-to-nanofiber geometric transformation under induction by plasma amine oxidase (PAO). PAO is commercially available and functionally similar to lysyl oxidase (LO), which is widely present in serum. After the addition of fetal bovine serum (FBS) or PAO, the secondary structure of the peptide changed, while the spherical nanoparticles stretched and transformed into nanofibers. The conversion of the self-assembled morphology reveals the susceptibility of this amphiphilic peptide to subtle chemical modifications and may lead to promising strategies to control self-assembled architecture via enzyme induction. Enzymatically self-assembled V₆K₃ had bactericidal properties after PAO addition that were surprisingly superior to those before PAO addition, enabling this peptide to be used to prevent infection. The amphiphilic peptide V₆K₃ displayed antitumor properties and low toxicity in mammalian cells, demonstrating good biocompatibility, as well as bactericidal properties, to prevent bacterial contamination. These advantages indicate that enzymatically self-assembled V₆K₃ has great biomedical application potential in cancer therapy.

A Theranostic Nanoprobe for Hypoxia Imaging and Photodynamic Tumor Therapy

Hypoxia is a common feature for most malignant tumors, which was also closely related to the oxygen-dependent photodynamic therapy. Based on Förster resonance energy transfer (FRET), a smart nanoprobe (designated as H-Probe) was designed in this paper for hypoxia imaging and photodynamic tumor therapy. Due to the FRET process, H-Probe could respond to hypoxia with a significant fluorescence recovery. Moreover, abundant in vitro investigations demonstrated that the photosensitizer of PpIX in H-Probe could generate large amounts of singlet oxygen to kill cancer cells in the presence of oxygen and light with appropriate wavelength. Also, intravenously injected H-Probe with light irradiation achieved an effective tumor inhibition in vivo with a reduced side effect. This original strategy of integrating hypoxia imaging and tumor therapy in one nanoplatform would promote the development of theranostic nanoplatform for tumor precision therapy.

Liposomes with pH responsive 'on and off' switches for targeted and intracellular delivery of antibiotics

pH responsive drug delivery systems are one of the new strategies to address the spread of bacterial resistance to currently used antibiotics. The aim of this study was to formulate liposomes with 'On' and 'Off'' pH responsive switches for infection site targeting. The vancomycin (VCM) loaded liposomes had sizes below 100 nm, at pH 7.4. The QL-liposomes had a negative zeta potential at pH 7.4 that switched to a positive charge at acidic pH. VCM release from the liposome was quicker at pH 6 than pH 7.4. The OA-QL-liposome showed 4-fold lower MIC at pH 7.4 and 8- and 16-fold lower at pH 6.0 against both MSSA and MRSA compared to the bare drug. OA-QL liposome had a 1266.67- and 704.33-fold reduction in the intracellular infection for TPH-1 macrophage and HEK293 cells respectively. In vivo studies showed that the amount of MRSA recovered from mice treated with formulations was 189.67 and 6.33-fold lower than the untreated and bare VCM treated mice respectively. MD simulation of the QL lipid with the phosphatidylcholine membrane (POPC) showed spontaneous binding of the lipid to the bilayer membrane both electrostatic and Van der Waals interactions contributed to the binding. These studies demonstrated that the 'On' and 'Off' pH responsive liposomes enhanced the activity targeted and intracellular delivery VCM.

Transition from vesicles to nanofibres in the enzymatic self-assemblies of an amphiphilic peptide as an antitumour drug carrier

Amphiphilic peptides modified by molecular design can self-assemble into specific nanostructures with interesting applications in the fields of biomedicine and biotechnology. Lysyl oxidase (LO) is ubiquitous in human serum. However, enzymatic self-assembly of amphiphilic peptides remains a challenge for lipid-soluble drug delivery under the induction of LO. Here, we designed a positively charged amphiphilic peptide, A₆K₂, that could stably self-assemble to form nanovesicles. The lysine in the peptide molecule could be covalently cross-linked under enzyme catalysis, and the major transition was from random coil to β-sheet secondary structures, eventually leading to the destruction of the peptide nanovesicles. The lipid-soluble antitumour drug doxorubicin (DOX) as a model drug could be loaded into the hydrophobic core of the nanovesicles formed by the amphiphilic peptide A₆K₂, even though DOX was not covalently linked to the peptide monomer. The amount of DOX-encapsulated A₆K₂ nanovesicles in human hepatocellular carcinoma BEL-7402 cells was significantly higher than that in human liver L02 cells, indicating excellent selectivity. The amphiphilic peptide A₆K₂ inhibited tumour cell growth and had low cytotoxicity to mammalian cells, and it showed antibacterial activity against G⁺ and G^- bacteria. These advantages make enzymatic self-assembling A₆K₂ nanovesicles of great interest in drug delivery for biomedical applications.

Impact of charge switching stimuli on supramolecular perylene monoimide assemblies

The development of stimuli-responsive amphiphilic supramolecular nanostructures is an attractive target for systems based on light-absorbing chromophores that can function as photosensitizers in water. We report here on a water soluble supramolecular carboxylated perylene monoimide system in which charge can be switched significantly by a change in pH. This was accomplished by substituting the perylene core with an ionizable hydroxyl group. In acidic environments, crystalline supramolecular nanoribbons with dimensions on the order of 500 × 50 × 2 nm form readily, while in basic solution the additional electrostatic repulsion of the ionized hydroxyl reduces assemblies to very small dimensions on the order of only several nanometers. The HOMO/LUMO levels were also found to be sensitive to pH; in acidic media the HOMO/LUMO levels are -5.65 and -3.70 eV respectively versus vacuum, whereas is in basic conditions they are -4.90 and -3.33 eV, respectively. Utilizing the assemblies as photosensitizers in photocatalytic production of hydrogen with [Mo3S13]2- as a catalyst at a pH of 4, H2 was generated with a turnover number of 125 after 18 hours. Charge switching the assemblies at a pH of 9-10 and using an iron porphyrin catalyst, protons could again be reduced to hydrogen and CO2 was reduced to CO with a turnover number of 30. The system investigated offers an example of dynamic photosensitizing assemblies that can drive reactions in both acidic and basic media.

Interactions of ficolin-3 with ovarian cancer cells

BACKGROUND

Ficolin-3 is a pattern-recognition molecule with the ability to activate the lectin pathway of complement. It is found in lung, liver and blood, but its physiological role is unclear. We have investigated interaction of recombinant ficolin-3 with malignant cells and tissues.

MATERIAL AND METHODS

Cells of various lines of human origin as well as ovarian tissue sections have been studied with the use of flow cytometry and immunohistochemistry.

RESULTS

Recombinant (but not serum-derived) ficolin-3 was found to bind strongly to the ovarian cancer cell lines, SKOV-3, OVCAR-3 and ES-2, at concentrations of 2.5 μg/ml and above. Moreover, His-tagged recombinant ficolin-3 (10 μg/ml) preferentially stained ovarian tissue sections from patients with malignant tumours compared with those from patients without. Binding to cell lines was inhibited by EDTA and specific carbohydrate ligands, indicating involvement of the fibrinogen-like domain. Binding was enhanced under mildly acidic conditions and at physiological pH after pre-incubation of cells with mildly acidic buffer.

CONCLUSION

Basing on data concerning recombinant protein, it may be suggested that ficolin-3 is involved in immune response in ovarian cancer. However, unidentified serum factor(s) seem(s) to protect cancer cells from recognition by natural or rficolin-3.

Supramolecular self-assembly of fluorescent peptide amphiphiles for accurate and reversible pH measurement

We report the synthesis and self-assembly of fluorescent peptide amphiphiles (NBD-PA) composed of a fluorescent NBD probe and a peptide derivative VVAADD with a C₁₂-alkyl-chain as the linker (NBD-C₁₂-VVAADD).

Radiofrequency-Triggered Drug Release from Nanoliposomes with Millimeter-Scale Resolution Using a Superimposed Static Gating Field

Drug delivery to a specific site in the body typically relies on the use of targeting agents that recognize a unique biomarker. Unfortunately, it is often difficult to identify unique molecular signatures that exist only at the site of interest. An alternative strategy is to deliver energy (e.g., light) to locally trigger release from a drug carrier; however, the use of this approach is limited because energy delivery to deep tissues is often impractical or invasive. In this work, radiofrequency-responsive superparamagnetic iron oxide nanoparticles (SPIONs) are used to trigger drug release from nanoscale vesicles. Because the body is inherently nonmagnetic, this approach allows for deep tissue targeting. To overcome the unfavorable meter-scale diffraction limit of SPION-compatible radiofrequency (RF) fields, a strong static gating field containing a sharp zero point is superimposed on the RF field. Only drug carriers that are at or near the zero point are susceptible to RF-triggered drug release, thereby localizing drug delivery with millimeter-scale resolution. This approach induces >40% drug release from thermally responsive doxorubicin-loaded liposomes within a 3.2 mm radius of the zero point with <10% release in the surrounding area, leading to a >2.5 therapeutic index in Huh 7 hepatocellular carcinoma cells.

Recent Advances in Targeted Tumor Chemotherapy Based on Smart Nanomedicines

Efficacy and safety of chemotherapeutic drugs constitute two major criteria in tumor chemotherapy. Nanomedicines with tumor-targeted properties hold great promise for improving the efficacy and safety. To design targeted nanomedicines, the pathological characteristics of tumors are extensively and deeply excavated. Here, the rationale, principles, and advantages of exploiting these pathological characteristics to develop targeted nanoplatforms for tumor chemotherapy are discussed. Homotypic targeting with the ability of self-recognition to source tumors is reviewed individually. In the meanwhile, the limitations and perspective of these targeted nanomedicines are also discussed.

Novel surfactant peptide for removal of biofilms

Conventional chemical surfactants attach on blots randomly, accompanied with health and environmental issues. To address this, a surfactant peptide was designed to mimic chemical surfactants with an affinity binding peptide as a hydrophobic tail for the cleanup of biofilm contaminations. The micelle forming and structural changes of the peptide in aqueous solution were systematically investigated. More importantly, the biofilm removal efficiency toward Escherichia coli O157:H7 biofilm reached 75% in neutral aqueous solutions at the concentration of 125 mg/L (critical micelle concentration 91 mg/L), a significant improvement in comparison to conventional surfactants and random surfactant peptide. The dynamic removal process reported by confocal laser scanning microscope (CLSM) also displayed the different constituents of biofilm blots, which associated with surfactant peptide binding efficiency. Hopefully, this surfactant strategy will eventually provide new scopes in the design of surface active biological agents.

Nanoparticles induced by embedding self-assembling cassette into glucagon-like peptide 1 for improving in vivo stability

The multiple physiologic characteristics of glucagon-like peptide 1 (GLP-1) make it a promising drug candidate for treating type 2 diabetes mellitus. However, the half-life of GLP-1 is short as a result of degradation by dipeptidyl peptidase IV and renal clearance. Stabilizing GLP-1 is therefore critical for its use in drug development. Self-assembling peptides are a class of peptides that undergo spontaneous assembly into ordered nanostructures. Recently, studies of self-assembling peptides as drug carriers have increased because of their enhanced stability. In the present study, GLP-1 was modified to incorporate the structural characteristics of self-assembling peptides aiming to generate a self-assembling GLP-1 derivative. Receptor binding capacity and insulinotropic effects were measured to investigate the physiologic functions of GLP-1, along with morphologic approaches to observe supramolecular formation on self-assembly at the nano scale. Finally, blood glucose regulation and body weight were monitored after administration of selected derivatives. Our findings revealed that cadyglp1e and cadyglp1m both exhibited improved stability even though different nanoshapes were observed for these two self-assembling peptides. Both cadyglp1e and cadyglp1m retained glucoregulatory activity after insulin stimulation and were potent drug candidates for long-acting GLP-1 derivatives to treat type 2 diabetes mellitus. Our findings support the feasibility of introducing self-assembly functions into peptides with poor stabilities, such as GLP-1.-Li, Y., Cui, T., Kong, X., Yi, X., Kong, D., Zhang, J., Liu, C., Gong, M. Nanoparticles induced by embedding self-assembling cassette into glucagon-like peptide 1 for improving in vivo stability.

Enhanced and Selective Antiproliferative Activity of Methotrexate-Functionalized-Nanocapsules to Human Breast Cancer Cells (MCF-7)

Methotrexate is a folic acid antagonist and its incorporation into nanoformulations is a promising strategy to increase the drug antiproliferative effect on human breast cancer cells by overexpressing folate receptors. To evaluate the efficiency and selectivity of nanoformulations containing methotrexate and its diethyl ester derivative, using two mechanisms of drug incorporation (encapsulation and surface functionalization) in the in vitro cellular uptake and antiproliferative activity in non-tumoral immortalized human keratinocytes (HaCaT) and in human breast carcinoma cells (MCF-7). Methotrexate and its diethyl ester derivative were incorporated into multiwall lipid-core nanocapsules with hydrodynamic diameters lower than 160 nm and higher drug incorporation efficiency. The nanoformulations were applied to semiconfluent HaCaT or MCF-7 cells. After 24 h, the nanocapsules were internalized into HaCaT and MCF-7 cells; however, no significant difference was observed between the nanoformulations in HaCaT (low expression of folate receptors), while they showed significantly higher cellular uptakes than the blank-nanoformulation in MCF-7, which was the highest uptakes observed for the drug functionalized-nanocapsules. No antiproliferative activity was observed in HaCaT culture, whereas drug-containing nanoformulations showed antiproliferative activity against MCF-7 cells. The effect was higher for drug-surface functionalized nanocapsules. In conclusion, methotrexate-functionalized-nanocapsules showed enhanced and selective antiproliferative activity to human breast cancer cells (MCF-7) being promising products for further in vivo pre-clinical evaluations.

Optimization of Weight Ratio for DSPE-PEG/TPGS Hybrid Micelles to Improve Drug Retention and Tumor Penetration

PURPOSE

To enhance therapeutic efficacy and prevent phlebitis caused by Asulacrine (ASL) precipitation post intravenous injection, ASL-loaded hybrid micelles with size below 40 nm were developed to improve drug retention and tumor penetration.

METHODS

ASL-micelles were prepared using different weight ratios of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethyleneglycol-2000 (DSPE-PEG₂₀₀₀) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) polymers. Stability of micelles was optimized in terms of critical micelle concentration (CMC) and drug release properties. The encapsulation efficiency (EE) and drug loading were determined using an established dialysis-mathematic fitting method. Multicellular spheroids (MCTS) penetration and cytotoxicity were investigated on MCF-7 cell line. Pharmacokinetics of ASL-micelles was evaluated in rats with ASL-solution as control.

RESULTS

The ASL-micelles prepared with DSPE-PEG₂₀₀₀ and TPGS (1:1, w/w) exhibited small size (~18.5 nm), higher EE (~94.12%), better sustained in vitro drug release with lower CMC which may be ascribed to the interaction between drug and carriers. Compared to free ASL, ASL-micelles showed better MCTS penetration capacity and more potent cytotoxicity. Pharmacokinetic studies demonstrated that the half-life and AUC values of ASL-micelles were approximately 1.37-fold and 3.49-fold greater than that of free ASL.

CONCLUSIONS

The optimized DSPE-PEG₂₀₀₀/TPGS micelles could serve as a promising vehicle to improve drug retention and penetration in tumor.

Reduction-responsive PEtOz-SS-PCL micelle with tailored size to overcome blood-brain barrier and enhance doxorubicin antiglioma effect

A series of novel reduction-responsive micelles with tailored size were designed and prepared to release doxorubicin (DOX) for treating glioma, which were developed based on amphiphilic block copolymer poly (2-ethyl-2-oxazoline)-b-poly (ε-caprolactone) (PEtOz-SS-PCL) and the micelle size could be regulated by designing the polymer structure. The DOX-loaded PEtOz-SS-PCL micelles had small size and rapid drug release in reductive intracellular environments. Biodistribution and in vivo imaging studies in C6 glioma mice tumor model showed that DOX loaded PEtOz-SS-PCL43 micelles with the smallest size had superior accumulation and fast drug release in tumor sites. In vivo antitumor activity demonstrated that DOX-loaded PEtOz-SS-PCL43 micelles improved antitumor efficacy in contrast to PEtOz-SS-PCL micelles with larger size toward the orthotopic C6-Luci cells-bearing mice. This study shows great potential in tailoring the micelle size and introducing the responsive bonds or compartment for intracellular drug delivery and release in glioma treatment by designing the architecture of the polymer.

Photocontrollable Probe Spatiotemporally Induces Neurotoxic Fibrillar Aggregates and Impairs Nucleocytoplasmic Trafficking

The abnormal assembly of misfolded proteins into neurotoxic aggregates is the hallmark associated with neurodegenerative diseases. Herein, we establish a photocontrollable platform to trigger amyloidogenesis to recapitulate the pathogenesis of amyotrophic lateral sclerosis (ALS) by applying a chemically engineered probe as a "switch" in live cells. This probe is composed of an amyloidogenic peptide from TDP-43, a photolabile linker, a polycationic sequence both to mask amyloidogenicity and for cell penetration, and a fluorophore for visualization. The photocontrollable probe can self-assemble into a spherical vesicle but rapidly develops massive nanofibrils with amyloid properties upon photoactivation. The photoinduced in vitro fibrillization process is characterized by biophysical techniques. In cellular experiments, this cell-penetrable vesicle was retained in the cytoplasm, seeded the mislocalized endogenous TDP-43 into aggregates upon irradiation, and consequently initiated apoptosis. In addition, this photocontrollable vesicle interfered with nucleocytoplasmic protein transport and triggered cortical neuron degeneration. Our developed strategy provides in vitro and in vivo spatiotemporal control of neurotoxic fibrillar aggregate formation, which can be readily applied in the studies of protein misfolding, aggregation-induced protein mislocalization, and amyloid-induced pathogenesis in different diseases.

K+ -Responsive Block Copolymer Micelles for Targeted Intracellular Drug Delivery

In this work, a novel type of block copolymer micelles with K⁺ -responsive characteristics for targeted intracellular drug delivery is developed. The proposed smart micelles are prepared by self-assembly of poly(ethylene glycol)-b-poly(N-isopropylacry-lamide-co-benzo-18-crown-6-acrylamide) (PEG-b-P(NIPAM-co-B18C6Am)) block copolymers. Prednisolone acetate (PA) is successfully loaded into the micelles as the model drug, with loading content of 4.7 wt%. The PA-loaded micelles display a significantly boosted drug release in simulated intracellular fluid with a high K⁺ concentration of 150 × 10^-3 m, as compared with that in simulated extracellular fluid. Moreover, the in vitro cell experiments indicate that the fluorescent molecules encapsulated in the micelles can be delivered and specifically released inside the HSC-T6 and HepG2 cells responding to the increase of K⁺ concentration in intracellular compartments, which confirms the successful endocytosis and efficient K⁺ -induced intracellular release. Such K⁺ -responsive block copolymer micelles are highly potential as new-generation of smart nanocarriers for targeted intracellular delivery of drugs.

Design of new acid-activated cell-penetrating peptides for tumor drug delivery

TH(AGYLLGHINLHHLAHL(Aib)HHIL-NH₂), a histidine-rich, cell-penetrating peptide with acid-activated pH response, designed and synthesized by our group, can effectively target tumor tissues with an acidic extracellular environment. Since the protonating effect of histidine plays a critical role in the acid-activated, cell-penetrating ability of TH, we designed a series of new histidine substituents by introducing electron donating groups (Ethyl, Isopropyl, Butyl) to the C-2 position of histidine. This resulted in an enhanced pH-response and improved the application of TH in tumor-targeted delivery systems. The substituents were further utilized to form the corresponding TH analogs (Ethyl-TH, Isopropyl-TH and Butyl-TH), making them easier to protonate for positive charge in acidic tumor microenvironments. The pH-dependent cellular uptake efficiencies of new TH analogs were further evaluated using flow cytometry and confocal laser scanning microscopy, demonstrating that ethyl-TH and butyl-TH had an optimal pH-response in an acidic environment. Importantly, the new TH analogs exhibited relatively lower toxicity than TH. In addition, these new TH analogs were linked to the antitumor drug camptothecin (CPT), while butyl-TH modified conjugate presented a remarkably stronger pH-dependent cytotoxicity to cancer cells than TH and the other conjugates. In short, our work opens a new avenue for the development of improved acid-activated, cell-penetrating peptides as efficient anticancer drug delivery vectors.

pH-responsive nanoparticle assembly from peptide amphiphiles for tumor targeting drug delivery

In this paper, the peptide amphiphiles (PA) which consists of RGDSEEEEEEEEEEK as pH-sensitive segment and stearic acid as hydrophobic segment named RGDS-E₁₀-Lys(C₁₈) was successfully synthesized. TEM images showed that uniformly dispersed nanoparticles could be formed by PA molecules in pH 7.4 medium, however, disintegrated in pH 5.0 medium. Circular dichroism (CD) spectrum indicated that polypeptide adopted a random-coil conformation in neutral medium (pH 7.4). The CD signal was significantly attenuate for decreased solubility of PA in medium with pH 5.0. As expected, the prepared RGDS-E₁₀-Lys(C₁₈) assembly showed high pH-sensitive property which demonstrated a much more rapid drug release from micelles in tumor tissue (acidic environment) than in physiological environment (neutral environment). After DOX-loaded micelles incubated with tumor cells, the cytotoxicity of the micelles against Hela cells was increased obviously, indicating the great potential of micelles developed here as promising vehicle for targeted pH-responsive drug delivery.

Gemcitabine Integrated Nano-Prodrug Carrier System

Peptide nanomaterials have received a great deal of interest in drug-delivery applications due to their biodegradability, biocompatibility, suitability for large-scale synthesis, high drug-loading capacities, targeting ability, and ordered structural organization. The covalent conjugation of drugs to peptide backbones results in prolonged circulation time and improved stability of drugs. Therapeutic efficacy of gemcitabine, which is used for breast cancer treatment, is severely compromised due to its rapid plasma degradation. Its hydrophilic nature poses a challenge for both its efficient encapsulation into nanocarrier systems and its sustained release property. Here, we designed a new peptide prodrug molecule for the anticancer drug gemcitabine, which was covalently conjugated to the C-terminal of 9-fluorenylmethoxy carbonyl (Fmoc)-protected glycine. The prodrug was further integrated into peptide nanocarrier system through noncovalent interactions. A pair of oppositely charged amyloid-inspired peptides (Fmoc-AIPs) were exploited as components of the drug-carrier system and self-assembled into one-dimensional nanofibers at physiological conditions. The gemcitabine integrated nanoprodrug carrier system exhibited slow release and reduced the cellular viability of 4T1 breast cancer cell line in a time- and concentration-dependent manner.

Electrostatic Control of Polymorphism in Charged Amphiphile Assemblies

Stimuli-induced structural transformations of molecular assemblies in aqueous solutions are integral to nanotechnological applications and biological processes. In particular, pH responsive amphiphiles as well as proteins with various degrees of ionization can reconfigure in response to pH variations. Here, we use in situ small and wide-angle X-ray scattering (SAXS/WAXS), transmission electron microscopy (TEM), and Monte Carlo simulations to show how charge regulation via pH induces morphological changes in the assembly of a positively charged peptide amphiphile (PA). Monte Carlo simulations and pH titration measurements reveal that ionic correlations in the PA assemblies shift the ionizable amine pK ∼ 8 from pK ∼ 10 in the lysine headgroup. SAXS and TEM show that with increasing pH, the assembly undergoes spherical micelle to cylindrical nanofiber to planar bilayer transitions. SAXS/WAXS reveal that the bilayer leaflets are interdigitated with the tilted PA lipid tails crystallized on a rectangular lattice. The details of the molecular packing in the membrane result from interplay between steric and van der Waals interactions. We speculate that this packing motif is a general feature of bilayers comprised of amphiphilic lipids with large ionic headgroups. Overall, our studies correlate the molecular charge and the morphology for a pH-responsive PA system and provide insights into the Å-scale molecular packing in such assemblies.

D-amino acid-containing supramolecular nanofibers for potential cancer therapeutics

Nanostructures formed by peptides that self-assemble in water through non-covalent interactions have attracted considerable attention because peptides possess several unique advantages, such as modular design and easiness of synthesis, convenient modification with known functional motifs, good biocompatibility, low immunogenicity and toxicity, inherent biodegradability, and fast responses to a wide range of external stimuli. After about two decades of development, peptide-based supramolecular nanostructures have already shown great potentials in the fields of biomedicine. Among a range of biomedical applications, using such nanostructures for cancer therapy has attracted increased interests since cancer remains the major threat for human health. Comparing with L-peptides, nanostructures containing peptides made of D-amino acid (i.e., D-peptides) bear a unique advantage, biostability (i.e., resistance towards most of endogenous enzymes). The exploration of nanostructures containing D-amino acids, especially their biomedical applications, is still in its infancy. Herein we review the recent progress of D-amino acid-containing supramolecular nanofibers as an emerging class of biomaterials that exhibit unique features for the development of cancer therapeutics. In addition, we give a brief perspective about the challenges and promises in this research direction.

Stereocomplex micelle efficiently transports Doxorubicin for enhanced lymphoma suppression in vivo

The application of Doxorubicin (DOX) in the chemotherapy for lymphoma is seriously hampered by the side effects of DOX, especially the cardiotoxicity and nephrotoxicity. Nanoscale micelle as a promising drug delivery system has gained more and more interest in malignancy chemotherapy. In this study, we successfully fabricated DOX-loaded stereocomplex micelle (SCM/DOX) from the equimolar mixture of the enantiomeric four-armed poly(ethylene glycol)-polylactide (PDM and PLM) copolymers. The SCM/DOX showed proper hydrodynamic size of ~90 nm and slow DOX release in phosphate-buffered saline at pH 7.4. The antitumor activities of DOX, PDM/DOX, PLM/DOX, and SCM/DOX toward lymphoma cells were tested in vitro and in vivo. Our data demonstrated that the SCM/DOX more effectively inhibited the cell proliferation than PDM/DOX, PLM/DOX, and free DOX in vitro. In the in vivo antitumor test, the SCM/DOX more effectively inhibited the growth of EL4 lymphoma, too. In addition, the body weight loss caused by SCM/DOX was alleviated than DOX. More importantly, the cardiotoxicity, nephrotoxicity, and hepatotoxicity caused by DOX in mice were obviously attenuated compared to the free DOX treatment group. Taken together, all the results indicated that the SCM/DOX could inhibit the growth of EL4 lymphoma cells and attenuate the toxicity of DOX more efficiently, which suggested SCM/DOX was promising for the prevention and treatment of lymphoma.

Stimuli-Responsive Codelivery of Oligonucleotides and Drugs by Self-Assembled Peptide Nanoparticles

Ever more emerging combined treatments exploiting synergistic effects of drug combinations demand smart, responsive codelivery carriers to reveal their full potential. In this study, a multifunctional stimuli-responsive amphiphilic peptide was designed and synthesized to self-assemble into nanoparticles capable of co-bearing and -releasing hydrophobic drugs and antisense oligonucleotides for combined therapies. The rational design was based on a hydrophobic l-tryptophan-d-leucine repeating unit derived from a truncated sequence of gramicidin A (gT), to entrap hydrophobic cargo, which is combined with a hydrophilic moiety of histidines to provide electrostatic affinity to nucleotides. Stimuli-responsiveness was implemented by linking the hydrophobic and hydrophilic sequence through an artificial amino acid bearing a disulfide functional group (H3SSgT). Stimuli-responsive peptides self-assembled in spherical nanoparticles in sizes (100-200 nm) generally considered as preferable for drug delivery applications. Responsive peptide nanoparticles revealed notable nucleotide condensing abilities while maintaining the ability to load hydrophobic cargo. The disulfide cleavage site introduced in the peptide sequence induced responsiveness to physiological concentrations of reducing agent, serving to release the incorporated molecules. Furthermore, the peptide nanoparticles, singly loaded or coloaded with boron-dipyrromethene (BODIPY) and/or antisense oligonucleotides, were efficiently taken up by cells. Such amphiphilic peptides that led to noncytotoxic, reduction-responsive nanoparticles capable of codelivering hydrophobic and nucleic acid payloads simultaneously provide potential toward combined treatment strategies to exploit synergistic effects.

Advancement in integrin facilitated drug delivery

The research of integrin-targeted anticancer agents has recorded important advancements in ingenious design of delivery systems, based either on the prodrug approach, or on nanoparticle carriers, but for now, none of these has reached a clinical stage of development. Past work in this area has been extensively reviewed by us and others. Thus, the purpose and scope of the present review is to survey the advancement reported in the last 3years, with focus on innovative delivery systems that appear to afford openings for future developments. These systems exploit the labelling with conventional and novel integrin ligands for targeting the interface of cancer cells and of endothelial cells involved in cancer angiogenesis, with the proteins of the extracellular matrix, in the circulation, in tissues, and in tumour stroma, as the site of progression and metastatic evolution of the disease. Furthermore, these systems implement the expertise in the development of nanomedicines to the purpose of achieving preferential biodistribution and uptake in cancer tissues, internalisation in cancer cells, and release of the transported drugs at intracellular sites. The assessment of the value of controlling these factors, and their combination, for future developments requires support of biological testing in appropriate mechanistic models, but also imperatively demand confirmation in therapeutically relevant in vivo models for biodistribution, efficacy, and lack of off-target effects. Thus, among many studies, we have tried to point out the results supported by relevant in vivo studies, and we have emphasised in specific sections those addressing the medical needs of drug delivery to brain tumours, as well as the delivery of oligonucleotides modulating gene-dependent pathological mechanism. The latter could constitute the basis of a promising third branch in the therapeutic armamentarium against cancer, in addition to antibody-based agents and to cytotoxic agents.

Stereocomplex micelle from nonlinear enantiomeric copolymers efficiently transports antineoplastic drug

Nanoscale polymeric micelles have attracted more and more attention as a promising nanocarrier for controlled delivery of antineoplastic drugs. Herein, the doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (PDM/DOX), poly(L-lactide)-based micelle (PLM/DOX), and stereocomplex micelle (SCM/DOX) from the equimolar mixture of the enantiomeric four-armed poly(ethylene glycol)-polylactide (PEG-PLA) copolymers were successfully fabricated. In phosphate-buffered saline (PBS) at pH 7.4, SCM/DOX exhibited the smallest hydrodynamic diameter (D h) of 90 ± 4.2 nm and the slowest DOX release compared with PDM/DOX and PLM/DOX. Moreover, PDM/DOX, PLM/DOX, and SCM/DOX exhibited almost stable D hs of around 115, 105, and 90 nm at above normal physiological condition, respectively, which endowed them with great potential in controlled drug delivery. The intracellular DOX fluorescence intensity after the incubation with the laden micelles was different degrees weaker than that incubated with free DOX · HCl within 12 h, probably due to the slow DOX release from micelles. As the incubation time reached to 24 h, all the cells incubated with the laden micelles, especially SCM/DOX, demonstrated a stronger intracellular DOX fluorescence intensity than free DOX · HCl-cultured ones. More importantly, all the DOX-loaded micelles, especially SCM/DOX, exhibited potent antineoplastic efficacy in vitro, excellent serum albumin-tolerance stability, and satisfactory hemocompatibility. These encouraging data indicated that the loading micelles from nonlinear enantiomeric copolymers, especially SCM/DOX, might be promising in clinical systemic chemotherapy through intravenous injection.

Selective intracellular drug delivery from pH-responsive polyion complex micelle for enhanced malignancy suppression in vivo

The pH-triggered intracellular drug delivery platforms have attracted great interest in malignancy therapy. Herein, a pH-responsive polyion complex (PIC) micelle from anionic acid-sensitive methoxy poly(ethylene glycol)-block-poly(N(ϵ)-((1-carboxy-cis-cyclohexene)-2-carbonyl)-L-lysine) (mPEG-b-PCLL) and cationic doxorubicin (DOX), a model anthracycline antitumor drug, was constructed by electrostatic interaction for directional intracellular drug delivery in malignancy chemotherapy. The PIC micelle kept constant diameter at physiological condition (i.e., pH 7.4), while gradually swelled and finally disassembled at mimicking intratumoral pH (i.e., 6.8) and especially intracellular endo/lysosomal pH (i.e., 5.5). The DOX release from the PIC micelle at pH 7.4 was slow, whereas obviously accelerated at the intracellular acidic condition of pH 5.5. These results should be related to the rapid cleavage of the side amide bond of mPEG-b-PCLL in an acidic environment. The PIC micelle exhibited satisfactory tumor suppression toward the H22 hepatoma-bearing BALB/c mouse model compared with free DOX, which was demonstrated by the upregulated tumor inhibition rate, and the increased necrotic and apoptosis areas in tumor tissue. Furthermore, the enhanced security was also observed in the PIC micelle group in relation to that of free DOX. The above results strongly supported that the acid-sensitive PIC micelle was promising for selective intracellular drug delivery along with upregulated malignancy inhibition.