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Berberine (Brb) is an active alkaloid occurring in various common plant species, with well-recognized potential for cancer therapy. Brb not only augments the efficacy of antineoplastic chemotherapy and radiotherapy but also exhibits direct antimitotic and proapoptotic actions, along with distinct antiangiogenic and antimetastatic activities in a variety of tumors. Despite its low systemic toxicity, several pharmaceutical challenges limit the application of Brb in cancer therapy (ie, extremely low solubility and permeability, very poor pharmacokinetics (PKs), and oral bioavailability). Among lipid-based nanocarriers investigated recently for Brb, stealth amphiphilic micelles of polymeric phospholipid conjugates were studied here as a promising strategy to improve Brb delivery to tumors. Specifically, physicochemically stable micelles made of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (PEG-PE) mixed with d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) (PEG-succinate ester of vitamin E), in a 3:1 M ratio, increased Brb solubilization by 300%. Our PEG-PE/TPGS-mixed micelles firmly retained the incorporated Brb, displaying extended-release profile in simulated media, with up to 30-fold projected improvement in simulated PKs of Brb. Owing to the markedly better uptake of Brb-containing mixed micelles in vitro, our Brb-mixed micelles nanoformulation significantly amplified apoptosis and overall cytotoxic effectiveness against monolayer and spheroid cultures of human prostate carcinomas (16- to 18-fold lower half-maximal inhibitory concentration values in PC3 and LNPaC, respectively), compared to free Brb. Mixed PEG-PE/TPGS micelles represent a promising delivery platform for the sparingly soluble anticancer agent, Brb, encouraging further pharmaceutical development of this drug for cancer therapy.

Indomethacin (IND) is a drug which after successful clinical trials became available for general prescription in 1965 and from that time is one of the most widely used anti-inflammatory drug with the highest potencies in the in vitro and in vivo models. However, despite its high therapeutic efficacy in relieving the symptoms of certain arthritis and in treating gout or collagen diseases, administration of IND causes a number of adverse effects, such as gastrointestinal ulceration, frequent central nervous system disorders and renal toxicity. These obstacles significantly limit the practical applications of IND and make that 10–20% of patients discontinue its use. Therefore, during the last three decades many attempts have been made to design novel formulations of IND aimed to increase its therapeutic benefits minimizing its adverse effects. In this review we summarize pharmacological information about IND and analyze its new lipid formulations and lipid bioconjugates as well as discuss their efficacy and potential application.

It is well known that the nonsteroidal anti-inflammatory drug (NSAID) indomethacin (IND) exhibits significant anticancer potential reported not only by in vitro and in vivo studies, but also in clinical trials. Despite promising results, IND is not widely used as an adjunctive agent in cancer therapy due to the occurrence of several gastrointestinal side effects, primarily after oral administration. Therefore, this study aimed to develop a nanosystem with reduced toxicity and risk of side effects for the delivery of IND for cancer treatment. IND was encapsulated in nanostructured lipid carriers (NLC) in the form of a phospholipid conjugate, where a covalent bond exists between the drug and phosphatidylcholine skeleton. For this purpose, seven new hybrid molecules were synthesized, and subsequently evaluated as anticancer agents in an in vitro model against selected cancer cell lines. Biological studies demonstrated that the synthesized conjugates possessed excellent antiproliferative effects, exhibiting a 2.7-fold to even 100-fold higher activity against selected cancer cells, while remaining non-toxic to healthy cells. Based on biological studies and molecular calculations, heterosubstituted phosphatidylcholine containing IND and oleic acid (IND-OA-PC) in the -1 and -2 positions, respectively, was identified as the most potent molecule. Subsequently, IND-OA-PC was encapsulated in nanostructured lipid carriers (IND-OA-PC-NLC). The results revealed that IND-OA-PC-NLC has a spherical shape with an average diameter of 155 nm and a negatively charged surface (-17.4 ± 0.49 mV). In this study, it was proven that the encapsulated conjugate of indomethacin with PC exhibits high activity against triple-negative (TNBC, Her2-, PR-, and ER-) breast cancer cells MDA-MB-468. While free IND was active at a concentration of 270.5 μM, in the form of the phospholipid conjugate (IND-OA-PC), it inhibited the growth of cancer cells at 67.5 μM and after conjugate encapsulation (IND-OA-PC-NLC) it was effective at only 10.3 μM. Our study revealed that the conjugation of NSAID with phosphatidylcholine and its combination with nanotechnology techniques create opportunities to repurpose well-known drugs from this group for new therapeutic applications.

Phospholipid conjugates consist of functionally different classes of molecules: phospholipid drug conjugates, fluorescent lipid probes and lipid molecular motors. All these conjugates are molecules that bear a functional group– a drug, a fluorophore or a molecular motor attached to the phospholipid. The conjugation is needed to incorporate a functional group into the lipid bilayer of liposome or lipid nanoparticle and thus, either modulate the effect of the drug or bring a new function to the liposome. Here, using NMR spectroscopy and quantum chemistry calculations, we show that phospholipid conjugates can form intramolecular π-cation complexes between quaternary ammonium group of the phosphatidylcholine and aromatic ring of the conjugated moiety. We also report on how to avoid the π-cation complex formation. If the linker between the aromatic moiety and the choline group is long enough the formation of π-cation complex is not observed.

Phospholipid‐based liposomes are among the most successful nanodrug delivery systems in clinical use. However, these conventional liposomes present significant challenges including low drug‐loading capacity and issues with drug leakage. Drug‐phospholipid conjugates (DPCs) and their assemblies offer a promising strategy for addressing these limitations. In this review, we summarize recent advances in the design, synthesis, and application of DPCs for drug delivery. We begin by discussing the chemical backbone structures and various design strategies such as phosphate head embedding and mono‐/bis‐embedding in the sn‐1/sn‐2 positions. Furthermore, we highlight stimulus‐responsive designs of DPCs and their applications in treating diseases such as cancer, inflammation, and malaria. Lastly, we explore future directions for DPCs development and their potential applications in drug delivery. Drug‐phospholipid conjugates (DPCs) possess the prodrug characteristics and self‐assembly abilities, making them a potential alternative to traditional phospholipids in the preparation of nanomedicines. The nano‐assemblies formed by DPCs exhibit decent advantages such as high drug‐loading capacity and strong stability, showing great translational potential in areas such as anti‐tumor, anti‐inflammation, anti‐malaria, anti‐epileptics and vaccines.

Biodegradable nanocarriers possess enormous potential for use as drug delivery systems that can accomplish controlled and targeted drug release, and a wide range of nanosystems have been reported for the treatment and/or diagnosis of various diseases and disorders. Of the various nanocarriers currently available, liposomes and polymer nanoparticles have been extensively studied and some formulations have already reached the market. However, a combination of properties to create a single hybrid system can give these carriers significant advantages, such as improvement in encapsulation efficacy, higher stability, and active targeting towards specific cells or tissues, over lipid or polymer-based platforms. To this aim, this work presents the formulation of poly(lactic- co -glycolic) acid (PLGA) nanoparticles in the presence of a hyaluronic acid (HA)-phospholipid conjugate (HA-DPPE), which was used to anchor HA onto the nanoparticle surface and therefore create an actively targeted hybrid nanosystem. Furthermore, ionic interactions have been proposed for drug encapsulation, leading us to select the free base form of pentamidine (PTM-B) as the model drug. We herein report the preparation of hybrid nanocarriers that were loaded via ion-pairing between the negatively charged PLGA and HA and the positively charged PTM-B, demonstrating an improved loading capacity compared to PLGA-based nanoparticles. The nanocarriers displayed a size of below 150 nm, a negative zeta potential of -35 mV, a core-shell internal arrangement and high encapsulation efficiency (90%). Finally, the ability to be taken up and exert preferential and receptor-mediated cytotoxicity on cancer cells that overexpress the HA specific receptor (CD44) has been evaluated. Competition assays supported the hypothesis that PLGA/HA-DPPE nanoparticles deliver their cargo within cells in a CD44-dependent manner. Graphical Abstract

We studied real-time interaction between poly(ethylene glycol)-conjugated phospholipids (PEG-lipids) and a supported lipid membrane by surface plasmon resonance (SPR) spectroscopy to understand dynamic behaviors of PEG-lipids on living cell membranes. Supported lipid membranes formed on a hydrophobic surface were employed as a model of living cell membrane. We prepared three kinds of PEG-lipids that carried alkyl chains of different lengths for SPR measurements and also performed fluorescence recovery after photobleaching (FRAP) to study the influence of acyl chain length on dynamics on the supported membrane. PEG-lipids were uniformly anchored to lipid membranes with high fluidity without clustering. Incorporation and dissociation rates of PEG-lipids into supported membranes strongly depended on the length of acyl chains; longer acyl chains reduced the incorporation rate and the dissociation rate of PEG-lipid. Furthermore, protein adsorption experiment with bovine serum albumin indicated that PEG modification prevented the adsorption of bovine serum albumin on such supported membrane.

Our laboratories first reported two novel classes of complex synthetic lipids, including alkylamidophosphocholines (PC lipid; CP-51) and alkylamidophosphate ester-linked lipid–AZT conjugates (lipid–AZT conjugates; CP-92), with selective and potent activity against human immunodeficiency virus type 1 (HIV-1). To extend these observations, we synthesized additional PC lipids and lipid–AZT conjugates (INK and INK–AZT conjugate) to evaluate their structure–activity relationships by testing for selectivity against infectious wild-type (wt) and drug-resistant HIV-1 replication, virus fusogenic activity and toxicity for mouse bone marrow cells. PC lipid compounds with medium chain lengths at positions 1 and 2 gave an improved selective index (SI). INK-3, with 12 and 8 carbons and INK-15, with 10 and 12 carbons were among the most selective when evaluated in CEM-SS cells. INK-14, a lipid–AZT conjugate where AZT replaced the choline in PC lipid INK-3, gave the highest SI of >1250 against both infectious wt HIV-1 replication in CEM-SS cells and a clinical isolate in peripheral blood leukocytes. Notably, the PC lipid compounds INK-3 and INK-15, but not the lipid–AZT conjugate INK-14, were potent inhibitors of matched pairs of AZT-sensitive and AZT-resistant HIV-1 clinical isolates. INK-3 also inhibited replication of HIV-2 and TIBO-resistant HIV-1, and inhibited HIV-1-mediated fusogenic activity by 78, 41 and 9% in a dose-dependent manner. The TC50 for mouse bone marrow cells was >100 μg/ml for INK-3 compared to 9.15–14.17 μg/ml for CP-51 and 0.142–0.259 μg/ml for AZT. These data suggest that optimum PC lipid compounds are significantly less toxic than AZT and have high potential as novel therapeutic agents for AIDS.

Effective anticancer nanomedicines need to exhibit prolonged circulation in blood, to extravasate and accumulate in tumours, and to be taken up by tumour cells. These contrasting criteria for persistent circulation and cell-membrane affinity have often led to complex nanoparticle designs with hampered clinical translatability. Here, we show that conjugates of small-molecule anticancer drugs with the polyzwitterion poly(2-( N -oxide- N , N -diethylamino)ethyl methacrylate) have long blood-circulation half-lives and bind reversibly to cell membranes, owing to the negligible interaction of the polyzwitterion with proteins and its weak interaction with phospholipids. Adsorption of the polyzwitterion–drug conjugates to tumour endothelial cells and then to cancer cells favoured their transcytosis-mediated extravasation into tumour interstitium and infiltration into tumours, and led to the eradication of large tumours and patient-derived tumour xenografts in mice. The simplicity and potency of the polyzwitterion–drug conjugates should facilitate the design of translational anticancer nanomedicines. Conjugates of small-molecule anticancer drugs with a polyzwitterion that has negligible interaction with proteins and a weak interaction with phospholipids eradicate large tumours and patient-derived tumour xenografts in mice.

Boron/nitrogen co-doped carbon nano-onions (BN-CNOs) are spherical nanoparticles that consist of multiple inter-nestled fullerene layers, giving them an onion-like internal structure. They have potential as nanocarriers due to their small size, aqueous dispersibility, and biocompatibility. The non-covalent attachment of a biocompatible polymer to BN-CNOs is a simple and effective method of creating a scaffold for a novel nanocarrier system as it allows for increased aqueous dispersibility whilst preventing the immune system from recognising the particle as a foreign object. The non-covalent approach also preserves the electronic and structural properties of the BN-CNOs. In this study, we attached a hyaluronic acid-phospholipid (HA-DMPE) conjugate polymer to the BN-CNO’s surface to improve its hydrophilicity and provide targetability toward HA-receptor overexpressing cancer cells. To this end, various ratios of HA-DMPE to BN-CNOs were investigated. The resulting supramolecular systems were characterised via UV-Vis absorption and FTIR spectroscopy, dynamic light scattering, and zeta potential techniques. It was found that the HA-DMPE conjugate polymer was permanently wrapped around the BN-CNO nanoparticle surface. Moreover, the resulting BN-CNO/HA-DMPE supramolecular systems displayed enhanced aqueous solubility compared to unfunctionalised BN-CNOs, with excellent long-term stability observed in aqueous dispersions.