Novel tetrapeptide, RGDF, mediated tumor specific liposomal doxorubicin (DOX) preparations

Advances in functional lipid nanoparticles: from drug delivery platforms to clinical applications

Since Doxil's first clinical approval in 1995, lipid nanoparticles have garnered great interest and shown exceptional therapeutic efficacy. It is clear from the licensure of two RNA treatments and the mRNA-COVID-19 vaccination that lipid nanoparticles have immense potential for delivering nucleic acids. The review begins with a list of lipid nanoparticle types, such as liposomes and solid lipid nanoparticles. Then it moves on to the earliest lipid nanoparticle forms, outlining how lipid is used in a variety of industries and how it is used as a versatile nanocarrier platform. Lipid nanoparticles must then be functionally modified. Various approaches have been proposed for the synthesis of lipid nanoparticles, such as High-Pressure Homogenization (HPH), microemulsion methods, solvent-based emulsification techniques, solvent injection, phase reversal, and membrane contractors. High-pressure homogenization is the most commonly used method. All of the methods listed above follow four basic steps, as depicted in the flowchart below. Out of these four steps, the process of dispersing lipids in an aqueous medium to produce liposomes is the most unpredictable step. A short outline of the characterization of lipid nanoparticles follows discussions of applications for the trapping and transporting of various small molecules. It highlights the use of rapamycin-coated lipid nanoparticles in glioblastoma and how lipid nanoparticles function as a conjugator in the delivery of anticancer-targeting nucleic acids. High biocompatibility, ease of production, scalability, non-toxicity, and tailored distribution are just a meager of the enticing allowances of using lipid nanoparticles as drug delivery vehicles. Due to the present constraints in drug delivery, more research is required to utterly realize the potential of lipid nanoparticles for possible clinical and therapeutic purposes.

Lipopeptides as tools in catalysis, supramolecular, materials and medicinal chemistry

Lipopeptides are amphiphilic peptides in which an aliphatic chain is attached to either the C or N terminus of peptides. Their self-assembly - into micelles, vesicles, nanotubes, fibres or nanobelts - leads to applications in nanotechnology, catalysis or medicinal chemistry. Self-organization of lipopeptides is dependent on both the length of the lipid tail and the amino acid sequence, in which the chirality of the peptide sequence can be transmitted into the supramolecular species. This Review describes the use of lipopeptides to design synthetic advanced dynamic supramolecular systems, nanostructured materials or self-responsive delivery systems in the area of medical biotechnology. We examine the influence of external stimuli, the ability of lipopeptide-derived structures to adapt over time and their application as medicinal agents with antibacterial, antifungal, antiviral or anticancer activities. Finally, we discuss the catalytic efficiency of lipopeptides, with the aim of building minimal synthetic enzymes, and recent efforts to incorporate metals into lipopeptide assemblies.

Pharmacokinetic Analysis of Peptide-Modified Nanoparticles with Engineered Physicochemical Properties in a Mouse Model of Traumatic Brain Injury

Peptides are used to control the pharmacokinetic profiles of nanoparticles due to their ability to influence tissue accumulation and cellular interactions. However, beyond the study of specific peptides, there is a lack of understanding of how peptide physicochemical properties affect nanoparticle pharmacokinetics, particularly in the context of traumatic brain injury (TBI). We engineered nanoparticle surfaces with peptides that possess a range of physicochemical properties and evaluated their distribution after two routes of administration: direct injection into a healthy mouse brain and systemic delivery in a mouse model of TBI. In both administration routes, we found that peptide-modified nanoparticle pharmacokinetics were influenced by the charge characteristics of the peptide. When peptide-modified nanoparticles are delivered directly into the brain, nanoparticles modified with positively charged peptides displayed restricted distribution from the injection site compared to nanoparticles modified with neutral, zwitterionic, or negatively charged peptides. After intravenous administration in a TBI mouse model, positively charged peptide-modified nanoparticles accumulated more in off-target organs, including the heart, lung, and kidneys, than zwitterionic, neutral, or negatively charged peptide-modified nanoparticles. The increase in off-target organ accumulation of positively charged peptide-modified nanoparticles was concomitant with a relative decrease in accumulation in the injured brain compared to zwitterionic, neutral, or negatively charged peptide-modified nanoparticles. Understanding how nanoparticle pharmacokinetics are influenced by the physicochemical properties of peptides presented on the nanoparticle surface is relevant to the development of nanoparticle-based TBI therapeutics and broadly applicable to nanotherapeutic design, including synthetic nanoparticles and viruses.

Albumin self-modified liposomes for hepatic fibrosis therapy via SPARC-dependent pathways

Activated hepatic stellate cells (HSCs) have a central role in the progression of liver fibrosis and express a large amount of secreted protein, acidic and rich in cysteine (SPARC), a specific protein-binding protein. In this study, we reported the preparation and evaluation of naringenin (Nar) -loaded albumin self-modified liposomes (NaAlLs), which delivered Nar, a specific Smad3 inhibitor that blocked the TGF-β/Smad3 signaling pathway and played an anti-fibrosis role. After a series of characterization, it was found that NaAlLs had favorable dispersion (PDI < 0.15) with an average particle size of about 120 nm and high entrapment efficiency (>85%), albumin coated the surface of liposomes or embedded in phospholipid bilayer by interaction with the encapsulated naringenin and phospholipid molecules during the preparation of liposomes. The amount of albumin modified to the surface of NaAlLs by this method is not only more than that of the physical adsorption method, but also the binding force between albumin and liposomes is stronger. The albumin modified to the surface of NaAlLs greatly reduced the aggregation of liposomes and drug leakage and increased the stability of liposomes. More importantly, the uptake of NaAlLs by activated HSCs was 1.5 times higher than that of Nar-loaded liposomes (NaLs), suggesting that NaAlLs specifically increased targeting of activated HSCs via albumin and SPARC-dependent pathways. As expected, NaAlLs was more effective in improving liver fibrosis than the NaLs or the inclusion complex solution of Nar and Hydroxypropyl-β-cyclodextrin (NaICS). The results suggested that NaAlLs was a promising drug delivery system, which could target drug delivery to activated HSC for the treatment of liver fibrosis.

Rational design and facile fabrication of biocompatible triple responsive dendrimeric nanocages for targeted drug delivery

Multi-responsive polymeric nanoparticles have shown great promise in the sufficient site-specific delivery of drugs in heterogeneous and complicated biological microenvironments, but without great success due to many problems such as sophisticated manufacture process, high cost and cytotoxicity. In this work, a novel triple responsive dendrimeric nanocage (TDN) is fabricated through co-assembling and cross-linking of lipoic acid modified low generation dendrimers with lipoic acid modified polyethylene glycols (PEGs). This nanocage exhibits improved drug loading capacity (about 2 times higher) at a lower temperature and stimuli-responsive drug release profile upon the stimulation of temperature, acid pH and reducing agent. More importantly, the nanocage promotes drug internalization, conduces endosomal escape, and realizes intracellular controlled drug release. Furthermore, the nanocage significantly improves the pharmacokinetics and biodistribution of antitumor drugs, confirming the potent in vivo therapeutic effect with reduced side effects. The rational design and facile fabrication of multi-responsive dendrimeric nanocages provide a "proof-of-concept" for precise targeted drug delivery, and may have great potential for clinical use in the future.

Functionalized Eu(III)-based nanoscale metal-organic framework for enhanced targeted anticancer therapy

To improve the cancer targeting and anticancer efficacy, the multifunctional Eu-based metal-organic framework (EuBTC) is post-synthetically modified with a targeting moiety folic acid and a zinc phthalocyanine photosensitizer. In addition, this nanosphere is also applied as a drug delivery system to load the chemical drug doxorubicin. Electron microscopy, powder X-ray diffraction and infrared spectometry demonstrated the formation of these multifunctional nanospheres (DOX). Our nanospheres kept the high singlet oxygen quantum yield of zinc phthalocyanine. Additionally, Cell viability experiments demonstrated the biosafety of EuBTC and the enhanced anticancer effect of DOX@FA-EuBTC-Pc under light irradiation. In short, these well-arranged DOX@FA-Eu-BTC-Pcs exhibit as promising drug delivery systems for enhanced targeted anticancer therapy.

A sequentially responsive and structure-transformable nanoparticle with a comprehensively improved 'CAPIR cascade' for enhanced antitumor effect

An intravenously administered drug delivery system should undergo a five-step 'CAPIR' cascade (circulation, accumulation, penetration, internalization and release), and the maximal efficiency of each step is of great importance to obtain the improved final therapeutic benefits and overall survival rate. Here, a pH/matrix metalloproteinase-9 (MMP9) sequentially responsive and continuously structure-transformable nanoparticle assembled from a doxorubicin (DOX)-conjugated peptide was exploited for comprehensively improving the 'CAPIR cascade' and eventually enhancing the therapeutic efficacy. The chimeric peptide can self-assemble into spherical nanoparticles (RGD-sNPs) at pH 7.4 with a particle size of 45.7 ± 5.4 nm. By a combination of passive and active targeting mechanisms, RGD-sNPs achieved efficient accumulation at the tumor site (∼15.1% ID g-1 within 24 h). Both in vitro and in vivo experiments revealed that RGD-sNPs can be transformed into rod-like nanoparticles (S-NFs) triggered by MMP9 that overexpressed in the tumor microenvironment, demonstrating remarkable advantages of deep tumor penetration, prolonged drug retention with ∼3.7% ID g-1 at 96 h, and 2-fold enhanced internalization. Subsequently, S-NFs would respond to the intracellular weakly acidic stimuli to rapidly release DOX for induction of cytotoxicity and apoptosis. Meanwhile, the remaining peptide was further converted into long fibers (length >5 μm) with significant cytotoxicity, thereby exerting a synergistic antitumor effect. Thus RGD-sNPs displayed superior antitumor efficacy and extended the median survival period to 55 days. This provides a new horizon for the exploration of high-performance antitumor nanomedicines.

Acid-active supramolecular anticancer nanoparticles based on cyclodextrin polyrotaxanes damaging both mitochondria and nuclei of tumor cells

Acid-active supramolecular theranostics based on cyclodextrin polyrotaxanes for enhanced cancer therapy.

Multifunctional hybrid micelles with tunable active targeting and acid/phosphatase-stimulated drug release for enhanced tumor suppression

Therapeutic efficacy of conventional single PEGylated polymeric micelles is significantly reduced by limited endocytosis and intracellular drug release. To improve drug delivery efficiency, poly (ethylene glycol)-block-poly (l-lactic acid)/(Arg-Gly-Asp-Phe)-poly (aminoethyl ethylene phosphate)-block-poly (l-lactic acid) (PEG-PLLA/RGDF-PAEEP-PLLA) hybrid micelles with tunable active targeting and acid/phosphatase-stimulated drug release are developed. The optimized hybrid micelles with 6 wt % of RGDF have favorable in vitro and in vivo activities. The hybrid micelles could temporarily shield the targeting efficacy of RGDF at pH 7.4 due to the steric effect exerted by concealment of RGDF peptides in the PEG corona, which strongly decreases the clearance by mononuclear phagocyte system and consequently improves the tumor accumulation. Inside the solid tumor with a lower acidic pH, the hybrid micelles restore the active tumor targeting property with exposed RGDF on the surface of the micelles because of the increased protonation and stretching degree of PAEEP blocks. RGDF-mediated endocytosis improves the tumor cell uptake. The hybrid micelles would also enhance intracellular drug release because of the hydrolysis of the acid/phosphatase-sensitivity of PAEEP blocks in endo/lysosome. Systemic administration of the hybrid micelles significantly inhibits tumor growth by 96% due to the integration of enhanced circulation time, tumor accumulation, cell uptake and intracellular drug release.

Modulating angiogenesis with integrin-targeted nanomedicines

Targeting angiogenesis-related pathologies, which include tumorigenesis and metastatic processes, has become an attractive strategy for the development of efficient guided nanomedicines. In this respect, integrins are cell-adhesion molecules involved in angiogenesis signaling pathways and are overexpressed in many angiogenic processes. Therefore, they represent specific biomarkers not only to monitor disease progression but also to rationally design targeted nanomedicines. Arginine-glycine-aspartic (RGD) containing peptides that bind to specific integrins have been widely utilized to provide ligand-mediated targeting capabilities to small molecules, peptides, proteins, and antibodies, as well as to drug/imaging agent-containing nanomedicines, with the final aim of maximizing their therapeutic index. Within this review, we aim to cover recent and relevant examples of different integrin-assisted nanosystems including polymeric nanoconstructs, liposomes, and inorganic nanoparticles applied in drug/gene therapy as well as imaging and theranostics. We will also critically address the overall benefits of integrin-targeting.

Preparation and evaluation of poly(l-histidine) based pH-sensitive micelles for intracellular delivery of doxorubicin against MCF-7/ADR cells

In this study, a pH-sensitive micelle self-assembled from poly(l-histidine) based triblock copolymers of poly(ethylene glycol)–poly(d,l-lactide)–poly(l-histidine) (mPEG-PLA-PHis) was prepared and used as the intracellular doxorubicin (Dox) delivery for cancer chemotherapy. Dox was loaded into the micelles by thin-film hydration method and a Box–Behnken design for three factors at three levels was used to optimize the preparations. The optimized mPEG-PLA-Phis/Dox micelles exhibited good encapsulation efficiency of 91.12%, a mean diameter of 45 nm and narrow size distribution with polydispersity index of 0.256. In vitro drug release studies demonstrated that Dox was released from the micelles in a pH-dependent manner. Furthermore, the cellular evaluation of Dox loaded micelles displayed that the micelles possessed high antitumor activity in vitro with an IC₅₀ of 35.30 µg/ml against MCF-7/ADR cells. The confocal microscopy and flow cytometry experiments indicated that mPEG-PLA-Phis micelles mediated efficient cytoplasmic delivery of Dox with the aid of poly(l-histidine) mediated endosomal escape. In addition, blank mPEG-PLA-Phis micelles were shown to be nontoxic to MCF-7/ADR cells even at a high concentration of 200 µg/ml. The pH-sensitive mPEG-PLA-PHis micelles have been demonstrated to be a promising nanosystem for the intracellular delivery of Dox for MDR reversal.

Novel Linear Peptides with High Affinity to αvβ3 Integrin for Precise Tumor Identification

Development of alternative linear peptides for targeting αvβ3 integrin has attracted much attention, as the traditional peptide ligand, cyclic RGD, is limited by inferior water-solubility and complex synthesis. Using pharmacophore-based virtual screening and high-throughput molecular docking, we identified two novel linear small peptides RWr and RWrNM with high affinity and specificity to αvβ3 integrin. The competitive binding with cyclic RGD (c(RGDyK)) and cellular uptake related to the integrin expression levels verified their affinity to αvβ3 integrin. The intermolecular interaction measurement and dynamics simulation demonstrated the high binding affinity and stability, especially for RWrNM. In vivo peptide-guided tumor imaging and targeted therapy further confirmed their specificity. Results indicated that the newly identified small linear peptide RWrNM, with high affinity and specificity to αvβ3 integrin, better water-solubility, and simplified synthetic process, could overcome limitations of the current cyclic RGD peptides, paving the way for diverse use in diagnosis and therapy.

Magnetic liposomes for colorectal cancer cells therapy by high-frequency magnetic field treatment

In this study, we developed the cancer treatment through the combination of chemotherapy and thermotherapy using doxorubicin-loaded magnetic liposomes. The citric acid-coated magnetic nanoparticles (CAMNP, ca. 10 nm) and doxorubicin were encapsulated into the liposome (HSPC/DSPE/cholesterol = 12.5:1:8.25) by rotary evaporation and ultrasonication process. The resultant magnetic liposomes (ca. 90 to 130 nm) were subject to characterization including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), zeta potential, Fourier transform infrared (FTIR) spectrophotometer, and fluorescence microscope. In vitro cytotoxicity of the drug carrier platform was investigated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L-929 cells, as the mammalian cell model. In vitro cytotoxicity and hyperthermia (inductive heating) studies were evaluated against colorectal cancer (CT-26 cells) with high-frequency magnetic field (HFMF) exposure. MTT assay revealed that these drug carriers exhibited no cytotoxicity against L-929 cells, suggesting excellent biocompatibility. When the magnetic liposomes with 1 μM doxorubicin was used to treat CT-26 cells in combination with HFMF exposure, approximately 56% cells were killed and found to be more effective than either hyperthermia or chemotherapy treatment individually. Therefore, these results show that the synergistic effects between chemotherapy (drug-controlled release) and hyperthermia increase the capability to kill cancer cells.

Novel peptide-doxorubucin conjugates for targeting breast cancer cells including the multidrug resistant cells

The efficacy of chemotherapeutic doxorubucin (Dox) in cancer treatment is limited by two main factors, nonspecific toxicity and the emergence of tumor resistance. To overcome these hurdles, in this study peptide-Dox conjugates were prepared. A decapeptide 18-4a (NH₂-WxEAAYQkFL-CONH₂) [corrected] with high specificity for breast cancer cells and improved proteolytic stability was conjugated to Dox to give peptide-Dox ester (1) and amide (2) conjugates. Cell uptake studies showed that the conjugates were 6-10 times selective for breast cancerous cells (MCF-7 and MDA-MB-435) over noncancerous cells (HUVECs and MCF-10A). Conjugate 1 displayed similar toxicity as free Dox toward the breast cancerous cells and was about 40 times less toxic toward the noncancerous cells and 4-fold more toxic toward the Dox resistant MDA-MB-435-MDR cells than the free Dox. These data suggest that conjugate 1 can be used as a potential prodrug for improving the therapeutic index of Dox and potentially many other cytotoxic drugs.

Current trends in the use of liposomes for tumor targeting

The use of liposomes for drug delivery began early in the history of pharmaceutical nanocarriers. These nanosized, lipid bilayered vesicles have become popular as drug delivery systems owing to their efficiency, biocompatibility, nonimmunogenicity, enhanced solubility of chemotherapeutic agents and their ability to encapsulate a wide array of drugs. Passive and ligand-mediated active targeting promote tumor specificity with diminished adverse off-target effects. The current field of liposomes focuses on both clinical and diagnostic applications. Recent efforts have concentrated on the development of multifunctional liposomes that target cells and cellular organelles with a single delivery system. This review discusses the recent advances in liposome research in tumor targeting.

Molecular imaging and therapeutic efficacy of 188Re-(DXR)-liposome-BBN in AR42J pancreatic tumor-bearing mice

Liposomes are good candidates as drug carriers and have been widely investigated in drug delivery systems. In this study, a new combination of bimodal 188Re-(DXR)-liposome-BBN radiochemotherapeutics was designed and studied for treating solid pancreatic tumor by intravenous administration. The in vivo nuclear microSPECT/CT imaging of tumor targeting, prolonged survival time and therapeutic efficacy were evaluated in AR42J malignant pancreatic solid tumor-bearing nude mice. MicroSPECT/CT imaging of 188Re-liposome-BBN pointed to significant targeting in tumors at 24 h after intravenous injection (SUV=2.13 ± 0.98). Co-injection of a blocking dose of cold BBN (4 mg/kg) inhibited the accumulation of 188Re-liposome-BBN in tumors (SUV=1.82 ± 0.31). For therapeutic efficacy, inhibition of tumor growth in mice treated with 188Re-DXR-liposome-BBN was precisely controlled [mean growth inhibition rate (MGI) = 0.092] and had longer survival time [life-span (LS) = 86.96%] than those treated with anticancer drug 188Re-liposome-BBN (MGI = 0.130; LS = 75%), Lipo-Dox-BBN (MGI = 0.666; LS = 3.61%) and untreated control mice. An additive tumor regression effect was observed (CI 0.946) for co-delivery of 188Re-DXR-liposome-BBN radiochemotherapeutics. These results point to the potential benefit of the 188Re-(DXR)-liposome-BBN radiochemotherapeutics for adjuvant cancer treatment with applications in oncology.

Peptide targeted lipid nanoparticles for anticancer drug delivery

Encapsulating anticancer drugs in nanoparticles has proven to be an effective mechanism to alter the pharmacokinetic and pharmacodynamic profiles of the drugs, leading to clinically useful cancer therapeutics like Doxil and DaunoXome. Underdeveloped tumor vasculature and lymphatics allow these first-generation nanoparticles to passively accumulate within the tumor, but work to create the next-generation nanoparticles that actively participate in the tumor targeting process is underway. Lipid nanoparticles functionalized with targeting peptides are among the most often studied. The goal of this article is to review the recently published literature of targeted nanoparticles to highlight successful designs that improved in vivo tumor therapy, and to discuss the current challenges of designing these nanoparticles for effective in vivo performance.

18F-labeled pyrazolo[1,5-a]pyrimidine derivatives: synthesis from 2,4-dinitrobenzamide and tosylate precursors and comparative biological evaluation for tumor imaging with positron emission tomography

We previously reported ¹⁸F-labeled pyrazolo[1,5-a]pyrimidine derivatives: 7-(2-[¹⁸F]fluoroethylamino)-5-methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile ([¹⁸F]1) and N-(2-(3-cyano-5-methylpyrazolo[1,5-a]pyrimidin-7-ylamino)ethyl)-2-[¹⁸F]fluoro-4-nitro- benzamide ([¹⁸F]2). Preliminary biodistribution experiments of both compounds showed s slow clearance rate from excretory tissues which warranted further investigation for tumor imaging with PET. Here we modified [¹⁸F]1 and [¹⁸F]2 by introducing polar groups such as ester, hydroxyl and carboxyl and developed three additional ¹⁸F-18 labeled pyrazolo[1,5-a] pyrimidine derivatives: (3-Cyano-7-(2-[¹⁸F]fluoroethylamino)pyrazolo[1,5-a]-pyrimidin-5- yl)methyl acetate ([¹⁸F]3), 7-(2-[¹⁸F]fluoroethylamino)-5-(hydroxymethyl)pyrazolo[1,5-a]- pyrimidine-3-carbonitrile ([¹⁸F]4) and (S)-6-(3-cyano-5-methylpyrazolo[1,5-a]pyrimidin-7- ylamino)-2-(2-[¹⁸F]fluoro-4-nitrobenzamido)hexanoic acid ([¹⁸F]5). The radiolabeled probes were synthesized by nucleophilic substitution of the corresponding tosylate and nitro precursors with ¹⁸F-fluoride. In Vitro studies showed higher uptake of [¹⁸F]3 and [¹⁸F]4 than that of [¹⁸F]5 by S180 tumor cells. In Vivo biodistribution studies in mice bearing S180 tumors showed that the uptake of both [¹⁸F]3 and [¹⁸F]4 in tumors displayed an increasing trend while the uptake of [¹⁸F]5 in tumor decreased through the course of the 120 min study. This significant difference in tumor uptake was also found between [¹⁸F]1 and [¹⁸F]2. Thus, we compared the biological behavior of the five tracers and reported the tumor uptake kinetic differences between 2-[¹⁸F]fluoroethylamino- and 2-[¹⁸F]fluoro-4-nitro- benzamidopyrazolo[1,5-a] pyrimidine derivatives.