Squalenoyl nanomedicines as potential therapeutics

Old drug, new tricks: polymer-based nanoscale systems for effective cytarabine delivery

Cytarabine, an antimetabolite antineoplastic agent, has been utilized to treat various cancers. However, because of its short half-life, low stability, and limited bioavailability, achieving an optimal plasma concentration requires continuous intravenous administration, which can lead to toxicity in normal cells and tissues. Addressing these limitations is crucial to optimize the therapeutic efficacy of cytarabine while minimizing its adverse effects. The use of novel drug delivery systems, such as polymer-based nanocarriers have emerged as promising vehicles for targeted drug delivery due to their unique properties, including high stability, biocompatibility, and tunable release kinetics. In this review, we examine the application of various polymer-based nanocarriers, including polymeric nanoparticles, polymeric micelles, dendrimers, polymer-drug conjugates, and nano-hydrogels, for the delivery of cytarabine. The article highlights the limitations of conventional cytarabine administration which often lead to suboptimal therapeutic outcomes and systemic toxicity. The rationale for using polymer-based nanocarriers is discussed, highlighting their ability to overcome challenges by providing controlled drug release, improved stability, and enhanced targeting capabilities. In summary, this review offers a valuable resource for drug delivery scientists by providing insights into the design principles, formulation strategies, and potential applications of polymer-based nanocarriers that can enhance the therapeutic efficacy of cytarabine.

Lipid nanoparticles for RNA delivery: Self-assembling vs driven-assembling strategies

Among non-viral vectors, lipid nanovectors are considered the gold standard for the delivery of RNA therapeutics. The success of lipid nanoparticles for RNA delivery, with three products approved for human use, has stimulated further investigation into RNA therapeutics for different pathologies. This requires decoding the pathological intracellular processes and tailoring the delivery system to the target tissue and cells. The complexity of the lipid nanovectors morphology originates from the assembling of the lipidic components, which can be elicited by various methods able to drive the formation of nanoparticles with the desired organization. In other cases, pre-formed nanoparticles can be mixed with RNA to induce self-assembly and structural reorganization into RNA-loaded nanoparticles. In this review, the most relevant lipid nanovectors and their potentialities for RNA delivery are described on the basis of the assembling mechanism and of the particle architecture.

Candida glycerinogenes-Promoted α-Pinene and Squalene Co-production Strategy Based on α-Pinene Stress

α-Pinene is a naturally occurring monoterpene, which is widely used in fragrances, cosmetics, and foods. Due to the high cellular toxicity of α-pinene, this work considered the application of Candida glycerinogenes, an effective industrial strain with high resistance, in α-pinene synthesis. It was found that α-pinene-induced stress resulted in an intracellular accumulation of reactive oxygen species with an increased formation of squalene as a cytoprotective compound. As squalene is a downstream product in the mevalonate (MVA) pathway for α-pinene synthesis, a strategy based on the promotion of α-pinene and squalene co-production under α-pinene stress is proposed. By introducing the α-pinene synthesis pathway and enhancing the MVA pathway, the production of both α-pinene and squalene is increased. We have demonstrated that intracellular synthesis of α-pinene is effective in promoting squalene synthesis. The generation of intercellular reactive oxygen that accompanies α-pinene synthesis promotes squalene synthesis with a resultant cellular protection and upregulation of MVA pathway genes that facilitate α-pinene production. In addition, we have overexpressed phosphatase and introduced NPP as a substrate to synthesize α-pinene, where co-dependent fermentation yielded 208 mg/L squalene and 12.8 mg/L α-pinene. This work establishes a viable strategy to promote terpene-co-dependent fermentation based on stress.

Plasma membrane lipid bilayer is druggable: Selective delivery of gemcitabine-squalene nano-medicine to cancer cells

Up to now the lipid bilayers were rarely considered as targets in cancer therapy despite pronounced differences in lipid composition between plasma membranes of benign and malignant cells. In this study we demonstrate that the lipid bilayer of the plasma membrane is druggable and suitable for facilitating selective delivery of amphiphilic gemcitabine-squalene nanomedicines to cancer cells. Data from radioactive assays, fluorescent membrane probes and molecular dynamics simulations provide evidence of selective accumulation of gemcitabine-squalene in the plasma membranes with disrupted lipid asymmetry and its subsequent preferential uptake by malignant cells. This causes pronounced cytotoxicity on cancer cells in comparison to their benign counterparts originating from the same tissue.

Organization of the Interfacial Film of Nanoemulsions Stabilized by Porphyrin Derivatives

Photodynamic therapies combining the action of a photosensitizer (PS), molecular oxygen, and light make it possible to destroy certain infectious sites and tumors. The incorporation of photosensitizers in nanocarriers allows for better control of their distribution in tissues and increases their concentration in the area that will be then illuminated. Nanoemulsions of glyceryl trioctanoate (GTO) have been designed in which pyropheophobide a (Pyro-A) or its lipid conjugate (Pyro-Lipid) are both stabilizing and photostimulable agents. In this work, we studied by surface pressure measurements and Brewster angle microscopy (BAM) analysis the organization of the interfacial films of nanodroplets. Comparison of preformed porphyrin nanoemulsions and two porphyrin-GTO mixtures, one mimicking the composition of the nanoemulsions and the other that of a porphyrin-rich interfacial film, highlighted the role of GTO and porphyrin derivatives in the formation, organization, and elasticity of the interfacial films in nanoemulsions. Pyro-Lipid and GTO can mix, and some of the GTO molecules remain inserted in the interfacial film at high surface pressures. In contrast, Pyro-A and GTO do not mix well and tend to segregate, leaving Pyro-A alone in the condensed interfacial film. The results of this study demonstrate the importance of characterizing the interfacial properties of porphyrin derivatives and their interaction with the oil to design stable nanoemulsions with well-controlled optical properties.

Drug Self-Delivery Systems: Molecule Design, Construction Strategy, and Biological Application

Drug self-delivery systems (DSDSs) offer new ways to create novel drug delivery systems (DDSs). In typical DSDSs, therapeutic reagents are not considered passive cargos but active delivery agents of actionable targets. As an advanced drug delivery strategy, DSDSs with positive cooperativity of both free drugs and nanocarriers exhibit the clear merits of unprecedented drug-loading capacity, minimized systemic toxicity, and flexible preparation of nanoscale deliverables for passive targeted therapy. This review highlights the recent advances and future trends in DSDSs on the basis of two differently constructed structures: covalent and noncovalent bond-based DSDSs. Specifically, various chemical and architectural designs, fabrication strategies, and responsive and functional features are comprehensively discussed for these two types of DSDSs. In addition, additional comments on the current development status of DSDSs and the potential applications of their molecular designs are presented in the corresponding discussion. Finally, the promising potential of DSDSs in biological applications is revealed and the relationship between preliminary molecular design of DSDSs and therapeutic effects of subsequent DSDSs biological applications is clarified.

Exploration of natural product database for the identification of potent inhibitor against IDH2 mutational variants for glioma therapy

Mutation in isocitrate dehydrogenase 2 (mIDH2) is an oncogenic driver prevalently reported in various cancer types including gliomas. To date, enasidenib is the only FDA-approved drug widely used as a mIDH2 (R140Q) inhibitor. However, dose-limiting toxicity and modest brain penetrating capability restrict its use as a plausible mIDH2 inhibitor. Furthermore, secondary site mutations (Q316E and I319M) were identified in patients with enasidenib treatments resulting in acquired therapeutic resistance. Hence, in the present investigation, we aimed to identify novel and potent drug-like compounds to overcome the existing drawbacks using an integrated in-silico strategy. A sum of 1574 natural compounds from the naturally occurring plant-based anti-cancerous compound activity target (NPACT) database was proclaimed and subjected to molecular docking. The binding affinities of the resultant natural compounds were rescored using MM-GBSA scoring functions. The resultant lead molecules were subjected to anticancer activity prediction using the machine-learning model. Furthermore, the toxicity and drug-likeliness of the lead compounds were investigated using ADMET properties. Eventually, the integrated in silico approach resulted in a lead molecule, namely squalene (NPACT00954) against mIDH2 protein. The screened compound was subjected to mutational analysis accomplishing second-site mutations. Interestingly, squalene exhibited appreciable binding affinity alongside good brain penetrating potential than enasidenib. Indeed, the reproducibility and significance of our results are examined by running 3 replicas of 100-ns simulations per system using the random initial velocities of the atoms generated by Maxwell distribution at a given temperature. Thus, we hypothesize from our results that further optimization of squalene could be beneficial for the treatment and management of glioma in the near future.

Tailoring carrier-free nanocombo of small-molecule prodrug for combinational cancer therapy

The outcomes of monotherapy could not satisfy clinical cancer treatment owing to the challenges of tumor heterogeneity, multi-drug resistance, tumor metastasis and relapse. In response, the significance of combinational cancer therapy has been highlighted. Traditional combinational schemes usually utilize "free" drug for multi drug administration, independently. The diverse pharmacokinetics and biodistribution greatly hinder the antitumor effects and cause systematic toxicity. To tackle the hinderance, various nanoparticulate drug delivery systems (Nano-DDSs) have been developed. However, conventional Nano-DDSs encapsulate drugs into carrier materials through noncovalent interactions, resulting in low drug loading, fixed multi drug encapsulation ratio, chemical instability and carrier-associated toxicity. Recently, carrier-free nanocombos based on self-assembling small-molecule prodrugs (SPNCs) have emerged as a versatile Nano-DDSs for multiple drug delivery. Benefited by the self-assembly capability, SPNCs could be facilely fabricated with distinct merits of ultra-high drug loading, adjustable drug ratio and negligible carrier-associated toxicity. Herein, we summarize the latest trends of SPNCs. First, a basic review on self-assembling small-molecule prodrugs is presented. Additionally, facile techniques to prepare SPNCs are introduced. Furthermore, advanced combinational therapies based on SPNCs are spotlighted with special emphasis on synergistic mechanisms. Finally, future prospects and challenges are discussed.

Selective delivery of pentamidine toward cancer cells by self-assembled nanoparticles

Pentamidine (PTM) is an aromatic diamidine approved for the treatment of parasitic infections that has been recently proposed for possible repositioning as an anticancer drug. To this aim, efforts have been made to improve its therapeutic efficacy and reduce associated adverse effects through both covalent derivatization and association with nanocarriers. To efficiently encapsulate PTM into biocompatible nanoparticles and to enhance its selectivity toward cancer cells, a squalene (SQ) derivative (1,1',2-tris-norsqualenoic acid, SQ-COOH) was selected to prepare PTM-loaded nanocarriers. Indeed, SQ and its derivatives self-assemble into nanoparticles in aqueous media. Furthermore, SQ-bioconjugates strongly interact with low-density lipoproteins (LDL), thus favoring preferential accumulation in cells overexpressing the LDL receptor (LDLR). We report here the preparation of nanocarriers by ion-pairing between the negatively charged SQ-COOH and the positively charged PTM free base (PTM-B), which allowed the covalent grafting of SQ to PTM to be avoided. The nanoparticles were characterized (mean size < 200 nm and zeta potential < -20 mV for SQ-COOH/PTM-B 3:1 molar ratio) and molecular modelling studies of the SQ-COOH/PTM-B interaction confirmed the nanocarrier stability. Finally, the ability to indirectly target LDLR-overexpressing cancer cells was evaluated by in vitro cell viability assays and confirmed by LDLR silencing, serum privation and simvastatin treatment.

Safer plant-based nanoparticles for combating antibiotic resistance in bacteria: A comprehensive review on its potential applications, recent advances, and future perspective

BACKGROUND

Antibiotic resistance is one of the current threats to human health, forcing the use of drugs that are more noxious, costlier, and with low efficiency. There are several causes behind antibiotic resistance, including over-prescription of antibiotics in both humans and livestock. In this scenario, researchers are shifting to new alternatives to fight back this concerning situation.

SCOPE AND APPROACH

Nanoparticles have emerged as new tools that can be used to combat deadly bacterial infections directly or indirectly to overcome antibiotic resistance. Although nanoparticles are being used in the pharmaceutical industry, there is a constant concern about their toxicity toward human health because of the involvement of well-known toxic chemicals (i.e., sodium/potassium borohydride) making their use very risky for eukaryotic cells.

KEY FINDINGS AND CONCLUSIONS

Multiple nanoparticle-based approaches to counter bacterial infections, providing crucial insight into the design of elements that play critical roles in the creation of antimicrobial nanotherapeutic drugs, are currently underway. In this context, plant-based nanoparticles will be less toxic than many other forms, which constitute promising candidates to avoid widespread damage to the microbiome associated with current practices. This article aims to review the actual knowledge on plant-based nanoparticle products for antibiotic resistance and the possible replacement of antibiotics to treat multidrug-resistant bacterial infections.

Squalene-Based Nano-Assemblies Improve the Pro-Autophagic Activity of Trehalose

The disaccharide trehalose is a well-established autophagy inducer, but its therapeutic application is severely hampered by its low potency and poor pharmacokinetic profile. Thus, we targeted the rational design and synthesis of trehalose-based small molecules and nano objects to overcome such issues. Among several rationally designed trehalose-centered putative autophagy inducers, we coupled trehalose via suitable spacers with known self-assembly inducer squalene to yield two nanolipid-trehalose conjugates. Squalene is known for its propensity, once linked to a bioactive compound, to assemble in aqueous media in controlled conditions, internalizing its payload and forming nanoassemblies with better pharmacokinetics. We assembled squalene conjugates to produce the corresponding nanoassemblies, characterized by a hydrodynamic diameter of 188 and 184 nm and a high stability in aqueous media as demonstrated by the measured Z-potential. Moreover, the nanoassemblies were characterized for their toxicity and capability to induce autophagy in vitro.

Nanomedicine from amphiphilizedprodrugs: Concept and clinical translation

Nanomedicines generally consisting of carrier materials with small fractions of active pharmaceutical ingredients (API) have long been used to improve the pharmacokinetics and biodistributions, augment the therapeutic efficacies and mitigate the side effects. Amphiphilizing hydrophobic/hydrophilic drugs to prodrugs capable of self-assembly into well-defined nanostructures has emerged as a facile approach to fabricating nanomedicines because this amphiphilized prodrug (APD) strategy presents many advantages, including minimized use of inert carrier materials, well-characterized prodrug structures, fixed and high drug loading contents, 100% loading efficiency, and burst-free but controlled drug release. This review comprehensively summarizes recent advances in APDs and their nanomedicines, from the rationale and the stimuli-responsive linker chemistry for on-demand drug release to their progress to the clinics, clinical performance of APDs, as well as the challenges and perspective on future development.

Small-Molecule Prodrug Nanoassemblies: An Emerging Nanoplatform for Anticancer Drug Delivery

The antitumor efficiency and clinical translation of traditional nanomedicines is mainly restricted by low drug loading, complex preparation technology, and potential toxicity caused by the overused carrier materials. In recent decades, small-molecule prodrug nanoassemblies (SMP-NAs), which are formed by the self-assembly of prodrugs themselves, have been widely investigated with distinct advantages of ultrahigh drug-loading and negligible excipients-trigged adverse reaction. Benefited from the simple preparation process, SMP-NAs are widely used for chemotherapy, phototherapy, immunotherapy, and tumor diagnosis. In addition, combination therapy based on the accurate co-delivery behavior of SMP-NAs can effectively address the challenges of tumor heterogeneity and multidrug resistance. Recent trends in SMP-NAs are outlined, and the corresponding self-assembly mechanisms are discussed in detail. Besides, the smart stimuli-responsive SMP-NAs and the combination therapy based on SMP-NAs are summarized, with special emphasis on the structure-function relationships. Finally, the outlooks and potential challenges of SMP-NAs in cancer therapy are highlighted.

Gemcitabine lipid prodrug nanoparticles: Switching the lipid moiety and changing the fate in the bloodstream

A simple approach to achieve a lipoprotein (LP)-mediated drug delivery is to trigger the spontaneous drug insertion into endogenous lipoproteins in the bloodstream, by means of its chemical modification. Nanoparticles (NPs) made of the squalene-gemcitabine (SQGem) conjugate were found to have a high affinity for plasma lipoproteins while free gemcitabine did not, suggesting a key role of the lipid moiety in this event. Whether the drug conjugation to cholesterol, one of the major lipoprotein-transported lipids, could also promote an analogous interaction was a matter of question. NPs made of the cholesterol-gemcitabine conjugate (CholGem) have been herein thoroughly investigated for their blood distribution profile both in vitro and in vivo. Unexpectedly, contrarily to SQGem, no trace of the CholGem prodrug could be found in the lipoprotein fractions, nor was it interacting with albumin. The investigation of isolated NPs and NPs/LPs physical mixtures provided a further insight into the lack of interaction of CholGem NPs with LPs. Although essential for allowing the self-assembly of the prodrug into nanoparticles, the lipid moiety may not be sufficient to elicit interaction of the conjugated drug with plasma lipoproteins but the whole NP physicochemical features must be carefully considered.

Supramolecular organization and biological interaction of squalenoyl siRNA nanoparticles

Small interfering RNAs (siRNA) are attractive and powerful tools to inhibit the expression of a targeted gene. However, their extreme hydrophilicities combined with a negative charge and short plasma half-life counteract their use as therapeutics. Previously, we chemically linked siRNA to squalene (SQ) which self-assembled as nanoparticles (NPs) with pharmacological efficiency in cancers and recently in a hereditary neuropathy. In order to understand the siRNA-SQ NP assembly and fate once intravenously injected, the present study detailed characterization of siRNA-SQ NP structure and its interaction with serum components. From SAXS and SANS analysis, we propose that the siRNA-SQ bioconjugate self-assembled as 11-nm diameter supramolecular assemblies, which are connected one to another to form spherical nanoparticles of around 130-nm diameter. The siRNA-SQ NPs were stable in biological media and interacted with serum components, notably with albumin and LDL. The high specificity of siRNA to decrease or normalize gene expression and the high colloidal stability when encapsulated into squalene nanoparticles offer promising targeted therapy with wide applications for pathologies with gene expression dysregulation.

Decoration of Squalenoyl-Gemcitabine Nanoparticles with Squalenyl-Hydroxybisphosphonate for the Treatment of Bone Tumors

Therapeutic perspectives of bone tumors such as osteosarcoma remain restricted due to the inefficacy of current treatments. We propose here the construction of a novel anticancer squalene‐based nanomedicine with bone affinity and retention capacity. A squalenyl‐hydroxybisphosphonate molecule was synthetized by chemical conjugation of a 1‐hydroxyl‐1,1‐bisphosphonate moiety to the squalene chain. This amphiphilic compound was inserted onto squalenoyl‐gemcitabine nanoparticles using the nanoprecipitation method. The co‐assembly led to nanoconstructs of 75 nm, with different morphology and colloidal properties. The presence of squalenyl‐hydroxybisphosphonate enhanced the nanoparticles binding affinity for hydroxyapatite, a mineral present in the bone. Moreover, the in vitro anticancer activity was preserved when tested in commercial and patient‐treated derived pediatric osteosarcoma cells. Further in vivo studies will shed light on the potential of these nanomedicines for the treatment of bone sarcomas.

In silico study of PEI-PEG-squalene-dsDNA polyplex formation: the delicate role of the PEG length in the binding of PEI to DNA

Biocompatible hydrophilic polyethylene glycol (PEG) is widely used in biomedical applications, such as drug or gene delivery, tissue engineering or as an antifouling component in biomedical devices. Experimental studies have shown that the size of PEG can weaken polycation-polyanion interactions, like those between branched polyethyleneimine (b-PEI) and DNA in gene carriers, but details of its cause and underlying interactions on the atomic scale are still not clear. To better understand the interaction mechanisms in the formation of polyplexes between b-PEI-PEG based carriers and DNA, we have used a combination of in silico tools and experiments on three multicomponent systems differing in PEG MW. Using the PEI-PEG-squalene-dsDNA systems of the same size, both in the all-atom MD simulations and in experimental in-gel electrophoresis measurements, we found that the binding between DNA and the vectors is highly influenced by the size of PEG, with the binding efficiency increasing with a shorter PEG length. The mechanism of how PEG interferes with the binding between PEI and DNA is explained using a two-step MD simulation protocol that showed that the DNA-vector interactions are influenced by the PEG length due to the hydrogen bond formation between PEI and PEG. Although computationally demanding we find it important to study molecular systems of the same size both in silico and in a laboratory and to simulate the behaviour of the carrier prior to the addition of bioactive molecules to understand the molecular mechanisms involved in the formation of the polyplex.

Targeting Systems to the Brain Obtained by Merging Prodrugs, Nanoparticles, and Nasal Administration

About 40 years ago the lipidization of hydrophilic drugs was proposed to induce their brain targeting by transforming them into lipophilic prodrugs. Unfortunately, lipidization often transforms a hydrophilic neuroactive agent into an active efflux transporter (AET) substrate, with consequent rejection from the brain after permeation across the blood brain barrier (BBB). Currently, the prodrug approach has greatly evolved in comparison to lipidization. This review describes the evolution of the prodrug approach for brain targeting considering the design of prodrugs as active influx substrates or molecules able to inhibit or elude AETs. Moreover, the prodrug approach appears strategic in optimization of the encapsulation of neuroactive drugs in nanoparticulate systems that can be designed to induce their receptor-mediated transport (RMT) across the BBB by appropriate decorations on their surface. Nasal administration is described as a valuable alternative to obtain the brain targeting of drugs, evidencing that the prodrug approach can allow the optimization of micro or nanoparticulate nasal formulations of neuroactive agents in order to obtain this goal. Furthermore, nasal administration is also proposed for prodrugs characterized by peripheral instability but potentially able to induce their targeting inside cells of the brain.

Recent trends in bioresponsive linker technologies of Prodrug-Based Self-Assembling nanomaterials

Prodrugs are designed to improve pharmaceutical properties of potent compounds and represent a central approach in drug development. The success of the prodrug strategy relies on incorporation of a reversible linkage facilitating controlled release of the parent drug. While prodrug approaches enhance pharmacokinetic properties over their parent drug, they still face challenges in absorption, distribution, metabolism, elimination, and toxicity (ADMET). Conjugating a drug to a carrier molecule such as a polymer can create an amphiphile that self-assembles into nanoparticles. These nanoparticles display prolonged blood circulation and passive targeting ability. Furthermore, the drug release can be tailored using a variety of linkers between the parent drug and the carrier molecule. In this review, we introduce the concept of self-assembling prodrugs and summarize different approaches for controlling the drug release with a focus on the linker technology. We also summarize recent clinical trials, discuss the emerging challenges, and provide our perspective on the utility and future potential of this technology.

Biomimetic Gemcitabine-Lipid Prodrug Nanoparticles for Pancreatic Cancer

Gemcitabine (Gem) is a key drug for pancreatic cancer, yet limited by high systemic toxicity, low bioavailability and poor pharmacokinetic profiles. To overcome these limitations, Gem prodrug amphiphiles were synthesised with oleyl, linoleyl and phytanyl chains. Self-assembly and lyotropic mesophase behaviour of these amphiphiles were examined using polarised optical microscopy and Synchrotron SAXS (SSAXS). Gem-phytanyl was found to form liquid crystalline inverse cubic mesophase. This prodrug was combined with phospholipids and cholesterol to create biomimetic Gem-lipid prodrug nanoparticles (Gem-LPNP), verified by SSAXS and cryo-TEM to form liposomes. In vitro testing of the Gem-LPNP in several pancreatic cancer cell lines showed lower toxicity than Gem. However, in a cell line-derived pancreatic cancer mouse model Gem-LPNP displayed greater tumour growth inhibition than Gem using a fraction (<6 %) of the clinical dose and without any systemic toxicity. The easy production, improved efficacy and low toxicity of Gem-LPNP represents a promising new nanomedicine for pancreatic cancer.

Elongated self-assembled nanocarriers: From molecular organization to therapeutic applications

Self-assembled cylindrical aggregates made of amphiphilic molecules emerged almost 40 years ago. Due to their length up to micrometers, those particles display original physico-chemical properties such as important flexibility and, for concentrated samples, a high viscoelasticity making them suitable for a wide range of industrial applications. However, a quarter of century was needed to successfully take advantage of those improvements towards therapeutic purposes. Since then, a wide diversity of biocompatible materials such as polymers, lipids or peptides, have been developed to design self-assembling elongated drug nanocarriers, suitable for therapeutic or diagnostic applications. More recently, the investigation of the main forces driving the unidirectional growth of these nanodevices allowed a translation toward the formation of pure nanodrugs to avoid the use of unnecessary side materials and the possible toxicity concerns associated.

Investigation of squalene-doxorubicin distribution and interactions within single cancer cell using Raman microspectroscopy

Intracellular distribution of doxorubicin (DOX) and its squalenoylated (SQ-DOX) nanoparticles (NPs) form in murine lung carcinoma M109 and human breast carcinoma MDA-MB-231 cells was investigated by Raman microspectroscopy. Pharmacological data showed that DOX induced higher cytotoxic effect than SQ-DOX NPs. Raman data were obtained using single-point measurements and imaging on the whole cell areas. These data showed that after DOX treatment at 1 μM, the spectral features of DOX were not detected in the M109 cell cytoplasm and nucleus. However, the intracellular distribution of SQ-DOX NPs was higher than DOX in the same conditions. In addition, SQ-DOX NPs were localized into both cell cytoplasm and nucleus. After 5 μM treatment, Raman bands of DOX at 1211 and 1241 cm^-1 were detected in the nucleus. Moreover, the intensity ratio of these bands decreased, indicating DOX intercalation into DNA. However, after treatment with SQ-DOX NPs, the intensity of these Raman bands increased. Interestingly, with SQ-DOX NPs, the intensity of 1210/1241 cm^-1 ratio was higher suggesting a lower fraction of intercalated DOX in DNA and higher amount of non-hydrolyzed SQ-DOX. Raman imaging data confirm this subcellular localization of these drugs in both M109 and MDA-MB-231 cells. These finding brings new insights to the cellular characterization of anticancer drugs at the molecular level, particularly in the field of nanomedicine.

(Poly-cyanoacrylate) nanomedicines for cancer and beyond: Lessons learned

This « Magnum Opus » emphasizes that serendipity is a corner stone in research. The paths of discovery and innovation often result from the interdisciplinarity of scientific areas that are a priori disconnected from each other. In the 1970s, fundamental discoveries in cell biology led to unexpected advances in galenic pharmacy with the emergence of nanotechnologies for the intracellular delivery of non diffusing molecules. As well, fluorescein-loaded polyacrylamide nanocapsules were shown to deliver this fluorescent agent precisely into cellular lysosomes which represented a seminal observation. However, due to the lack of biodegradability of this carrier polymer, this approach was still far from therapeutic application. The use of cyanoacrylates as surgical glue inspired us to use this material in the design of the first biodegradable nanoparticles for human use. Capable of transporting compounds with anti-tumor activity, these polyalkylcyanoacrylate nanoparticles demonstrated the unexpected property of overcoming multi-drug resistance. This discovery led to the development of a nanomedicine that has completed phase III clinical trials for the treatment of resistant hepatocarcinoma. Going beyond the state-of-the art, a step ahead in the nanomedicine field was the drug « squalenoylation » technology, which represents a shift from the « physical » to the « chemical » encapsulation paradigm. The bioconjugation of anticancer and other drugs to squalene, a natural and biocompatible lipid, enabled a dramatic increase in drug payload, and eliminated the so-called « burst release » of drug: Two major drawbacks commonly associated with drug nanoencapsulation. The drug « squalenoylation » approach resulted in a generic nanomedicine platform with broad pharmacological applications.

Gemcitabine Lipid Prodrugs: The Key Role of the Lipid Moiety on the Self-Assembly into Nanoparticles

A small library of amphiphilic prodrugs has been synthesized by conjugation of gemcitabine (Gem) (a hydrophilic nucleoside analogue) to a series of lipid moieties and investigated for their capacity to spontaneously self-assemble into nanosized objects by simple nanoprecipitation. Four of these conjugates formed stable nanoparticles (NPs), while with the others, immediate aggregation occurred, whatever the tested experimental conditions. Whether such capacity could have been predicted based on the prodrug physicochemical features was a matter of question. Among various parameters, the hydrophilic-lipophilic balance (HLB) value seemed to hold a predictive character. Indeed, we identified a threshold value which well correlated with the tendency (or not) of the synthesized prodrugs to form stable nanoparticles. Such a hypothesis was further confirmed by broadening the analysis to Gem and other nucleoside prodrugs already described in the literature. We also observed that, in the case of Gem prodrugs, the lipid moiety affected not only the colloidal properties but also the in vitro anticancer efficacy of the resulting nanoparticles. Overall, this study provides a useful demonstration of the predictive potential of the HLB value for lipid prodrug NP formulation and highlights the need of their opportune in vitro screening, as optimal drug loading does not always translate in an efficient biological activity.

New Nanoparticle Formulation for Cyclosporin A: In Vitro Assessment

Cyclosporin A (CsA) is a molecule with well-known immunosuppressive properties. As it also acts on the opening of mitochondrial permeability transition pore (mPTP), CsA has been evaluated for ischemic heart diseases (IHD). However, its distribution throughout the body and its physicochemical characteristics strongly limit the use of CsA for intravenous administration. In this context, nanoparticles (NPs) have emerged as an opportunity to circumvent the above-mentioned limitations. We have developed in our laboratory an innovative nanoformulation based on the covalent bond between squalene (Sq) and cyclosporin A to avoid burst release phenomena and increase drug loading. After a thorough characterization of the bioconjugate, we proceeded with a nanoprecipitation in aqueous medium in order to obtain SqCsA NPs of well-defined size. The SqCsA NPs were further characterized using dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryoTEM), and high-performance liquid chromatography (HPLC), and their cytotoxicity was evaluated. As the goal is to employ them for IHD, we evaluated the cardioprotective capacity on two cardiac cell lines. A strong cardioprotective effect was observed on cardiomyoblasts subjected to experimental hypoxia/reoxygenation. Further research is needed in order to understand the mechanisms of action of SqCsA NPs in cells. This new formulation of CsA could pave the way for possible medical application.

Cellular Targeting of Oligonucleotides by Conjugation with Small Molecules

Drug candidates derived from oligonucleotides (ON) are receiving increased attention that is supported by the clinical approval of several ON drugs. Such therapeutic ON are designed to alter the expression levels of specific disease-related proteins, e.g., by displaying antigene, antisense, and RNA interference mechanisms. However, the high polarity of the polyanionic ON and their relatively rapid nuclease-mediated cleavage represent two major pharmacokinetic hurdles for their application in vivo. This has led to a range of non-natural modifications of ON structures that are routinely applied in the design of therapeutic ON. The polyanionic architecture of ON often hampers their penetration of target cells or tissues, and ON usually show no inherent specificity for certain cell types. These limitations can be overcome by conjugation of ON with molecular entities mediating cellular 'targeting', i.e., enhanced accumulation at and/or penetration of a specific cell type. In this context, the use of small molecules as targeting units appears particularly attractive and promising. This review provides an overview of advances in the emerging field of cellular targeting of ON via their conjugation with small-molecule targeting structures.

Challenges and opportunities in the delivery of cancer therapeutics: update on recent progress

Global cancer prevalence has continuously increased in the last decades despite substantial progress achieved for patient care. Cancer is no longer recognized as a singular disease but as a plurality of different ones, leading to the important choice of the drug administration route and promoting the development of novel drug-delivery systems (DDS). Due to their structural diversity, therapeutic cancer drugs present specific challenges in physicochemical properties that can adversely affect their efficacy and toxicity profile. These challenges are addressed by innovative DDS to improve bioavailability, pharmacokinetics and biodistribution profiles. Here, we define the drug delivery challenges related to oral, intravenous, subcutaneous or alternative routes of administration, and review innovative DDS, marketed or in development, that answer those challenges.

Gemcitabine-retinoid prodrug loaded nanoparticles display in vitro antitumor efficacy towards drug-resilient human PANC-1 pancreatic cancer cells

The treatment of pancreatic cancer with gemcitabine is hampered by its rapid metabolism in vivo, the dense stroma around the tumor site which prevents the drug from reaching the cancerous cells and drug resistance. To address these challenges, this study describes the preparation of a retinoid prodrug of gemcitabine, GemRA (gemcitabine conjugated to retinoic acid), and its formulation into a nanoparticulate system applicable for pancreatic cancer treatment. Retinoic acid targets stellate cells which are part of the stroma and can thus augment the delivery of gemcitabine. GemRA dissolved in dimethylsulfoxide presented efficacy towards PANC-1 (human) and mT4 (mouse) pancreatic cancer cell lines but its poor solubility in aqueous solution affects its applicability. Thus, the preparation of the nanoparticles was initially attempted through self-assembly of GemRA, which resulted in the formation of unstable aggregates that precipitated during preparation. As a result, encapsulation of the drug into micelles of polyethylene glycol-retinoic acid (PGRA) amphiphilic conjugates was accomplished and resulted in successful incorporation of GemRA into nanoparticles of ca. 33 nm by dynamic light scattering and 25 nm by transmission electron microscopy. The nanoparticles had good stability in aqueous media and protected gemcitabine from the enzymatic action of cytidine deaminase, which converts gemcitabine to its inactive metabolite upon circulation. Cellular uptake of the nanoparticles by PANC-1 cells was confirmed by fluorescence spectroscopy and flow cytometry. Treatment of PANC-1 cells in vitro with the prodrug-loaded nanoparticles resulted in a significant reduction in cell viability (IC50 ca. 5 μM) compared to treatment with gemcitabine (IC50 > 1000 μM). The ability of the GemRA-loaded nanoparticles to induce cellular apoptosis of treated PANC-1 cells was ascertained via a TUNEL assay suggesting these nanoparticles are effective in pancreatic cancer treatment.

Tofacitinib Loaded Squalenyl Nanoparticles for Targeted Follicular Delivery in Inflammatory Skin Diseases

Tofacitinib (TFB), a Janus kinase inhibitor, has shown excellent success off-label in treating various dermatological diseases, especially alopecia areata (AA). However, TFB's safe and targeted delivery into hair follicles (HFs) is highly desirable due to its systemic adverse effects. Nanoparticles (NPs) can enhance targeted follicular drug delivery and minimize interfollicular permeation and thereby reduce systemic drug exposure. In this study, we report a facile method to assemble the stable and uniform 240 nm TFB loaded squalenyl derivative (SqD) nanoparticles (TFB SqD NPs) in aqueous solution, which allowed an excellent loading capacity (LC) of 20%. The SqD NPs showed an enhanced TFB delivery into HFs compared to the aqueous formulations of plain drug in an ex vivo pig ear model. Furthermore, the therapeutic efficacy of the TFB SqD NPs was studied in a mouse model of allergic dermatitis by ear swelling reduction and compared to TFB dissolved in a non-aqueous mixture of acetone and DMSO (7:1 v/v). Whereas such formulation would not be acceptable for use in the clinic, the TFB SqD NPs dispersed in water illustrated a better reduction in inflammatory effects than plain TFB's aqueous formulation, implying both encouraging good in vivo efficacy and safety. These findings support the potential of TFB SqD NPs for developing a long-term topical therapy of AA.

Synthesis and Biopharmaceutical Characterization of Amphiphilic Squalenyl Derivative Based Versatile Drug Delivery Platform

Limited drug loading capacity (LC), mostly below 5% w/w, is a significant drawback of nanoparticulate drug delivery systems (DDS). Squalenoylation technology, which employs bioconjugation of squalenyl moiety and drug, allows self-assemble of nanoparticles (NPs) in aqueous media with significantly high LC (>30% w/w). The synthesis and particle preparation of squalenoylated prodrugs are, however, not facile for molecules with multiple reactive groups. Taking a different approach, we describe the synthesis of amphiphilic squalenyl derivatives (SqDs) as well as the physicochemical and biopharmaceutical characterizations of their self-assembled NPs as DDSs. The SqDs included in this study are (i) cationic squalenyl diethanolamine (ii) PEGylated SqD (PEG 750 Da), (iii) PEGylated SqD (PEG 3,000 Da), and (iv) anionic squalenyl hydrogen sulfate. All four SqDs self-assemble into NPs in a size range from 100 to 200 nm in an aqueous solution. Furthermore, all NP derivatives demonstrate appropriate biocompatibility and adequate colloidal stability in physiological relevant pH environments. The mucoprotein binding of PEGylated NPs is reduced compared to the charged NPs. Most importantly, this technology allows excellent LC (at maximum of 45% w/w) of a wide range of multifunctional compounds, varying in physicochemical properties and molecular weight. Interestingly, the drug release profile can be tuned by different loading methods. In summary, the SqD-based NPs appear as versatile drug delivery platforms.

Design and characterization of Squalene-Gusperimus nanoparticles for modulation of innate immunity

Immunosuppressive drugs are widely used for the treatment of autoimmune diseases and to prevent rejection in organ transplantation. Gusperimus is a relatively safe immunosuppressive drug with low cytotoxicity and reversible side effects. It is highly hydrophilic and unstable. Therefore, it requires administration in high doses which increases its side effects. To overcome this, here we encapsulated gusperimus as squalene-gusperimus nanoparticles (Sq-GusNPs). These nanoparticles (NPs) were obtained from nanoassembly of the squalene gusperimus (Sq-Gus) bioconjugate in water, which was synthesized starting from squalene. The size, charge, and dispersity of the Sq-GusNPs were optimized using the response surface methodology (RSM). The colloidal stability of the Sq-GusNPs was tested using an experimental block design at different storage temperatures after preparing them at different pH conditions. Sq-GusNPs showed to be colloidally stable, non-cytotoxic, readily taken up by cells, and with an anti-inflammatory effect sustained over time. We demonstrate that gusperimus was stabilized through its conjugation with squalene and subsequent formation of NPs allowing its controlled release. Overall, the Sq-GusNPs have the potential to be used as an alternative in approaches for the treatment of different pathologies where a controlled release of gusperimus could be required.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Advanced nanomedicines for the treatment of inflammatory diseases

Inflammation, a common feature of many diseases, is an essential immune response that enables survival and maintains tissue homeostasis. However, in some conditions, the inflammatory process becomes detrimental, contributing to the pathogenesis of a disease. Targeting inflammation by using nanomedicines (i.e. nanoparticles loaded with a therapeutic active principle), either through the recognition of molecules overexpressed onto the surface of activated macrophages or endothelial cells, or through enhanced vasculature permeability, or even through biomimicry, offers a promising solution for the treatment of inflammatory diseases. After providing a brief insight on the pathophysiology of inflammation and current therapeutic strategies, the review will discuss, at a pre-clinical stage, the main innovative nanomedicine approaches that have been proposed in the past five years for the resolution of inflammatory disorders, finally focusing on those currently in clinical trials.

Self-assembling prodrug nanotherapeutics for synergistic tumor targeted drug delivery

Self-assembling prodrugs represents a robust and effective nanotherapeutic approach for delivering poorly soluble anticancer drugs. With numerous intrinsic advantages, self-assembling prodrugs possess the maximum drug loading capacity, controlled drug release kinetics, prolonged blood circulation, and preferential tumor accumulation based on the enhanced permeability and retention (EPR) effect. These prodrug conjugates allow for efficient self-assembly into nanodrugs with the potential of encapsulating other therapeutic agents that have different molecular targets, enabling simultaneous temporal-spatial release of drugs for synergistic antitumor efficacy with reduced systemic side effects. The aim of this review is to summarize the recent progress of self-assembling prodrug cancer nanotherapeutics that are made through conjugating therapeutically active agents to Polyethylene glycol, Vitamin E, or drugs with different physicochemical properties via rational design, for synergistic tumor targeted drug delivery.

Statement of Significance

All current FDA-approved nanomedicines use inert biomaterials as drug delivery carriers. These biomaterials lack any therapeutic potential, contributing not only to the cost, but may also elicit severe unfavorable adverse effects. Despite the reduction in toxicity associated with the payload, these nanotherapeutics have been met with limited clinical success, likely due to the monotherapy regimen. The self-assembling prodrug (SAP) has been emerging as a powerful platform for enhancing efficacy through co-delivering other therapeutic modalities with distinct molecular targets. Herein, we opportunely present a comprehensive review article summarizing three unique approaches of making SAP for synergistic drug delivery: pegylation, vitamin E-derivatization, and drug-drug conjugation. These SAPs may inevitably pave the way for developing more efficacious, clinically translatable, combination cancer nanotherapies.

Combinatorial Nanomedicine Made of Squalenoyl-Gemcitabine and Edelfosine for the Treatment of Osteosarcoma

Due to chemoresistance and a high propensity to form lung metastasis, survival rates in pediatric osteosarcoma (OS) are poor. With the aim to improve anticancer activity in pediatric OS, a multidrug nanomedicine was designed using the alkyl-lysophospholipid edelfosine (EF) co-assembled with squalenoyl–gemcitabine (SQ–Gem) to form nanoassemblies (NAs) of 50 nm. SQ–Gem/EF NAs modified the total Gem pool exposure in the blood stream in comparison with SQ–Gem NAs, which correlated with a better tolerability and a lower toxicity profile after multiple intravenous administrations in mice. For in vivo preclinical assessment in an orthotopic OS tumor model, P1.15 OS cells were intratibially injected in athymic nude mice. SQ–Gem/EF NAs considerably decreased the primary tumor growth kinetics and reduced the number of lung metastases. Our findings support the candidature of this anticancer nanomedicine as a potential pediatric OS therapy.

Dually Enzyme- and Acid-Triggered Self-Immolative Ketal Glycoside Nanoparticles for Effective Cancer Prodrug Monotherapy

The use of glycoside prodrugs is a promising strategy for developing new targeted medicines for chemotherapy. However, the in vivo utility of such prodrugs is hindered by insufficient activation and the lack of convenient synthetic methods. We have developed an innovative strategy for synthesizing ketal glycoside prodrugs that are unique in being activated by a dual enzyme- and acid-triggered self-immolative mechanism. Amphiphilic glucosyl acetone-based ketal-linked etoposide glycoside prodrug isomers were synthesized and fabricated into excipient-free nanoparticles for effective cancer prodrug monotherapy. Hydrolysis of the glycosidic linkage or the ketal linkage triggered hydrolysis of the other linkage, which resulted in spontaneous self-immolative hydrolysis of the prodrugs. Nanoparticles of the prodrug isomer that was the most labile in a lysosome-mimicking environment displayed high intratumoral accumulation and strong antitumor activity in an A549 xenograft mouse model. Our strategy may be useful for the development of stimulus-responsive self-immolative prodrugs and their nanomedicines.

Antiviral activity of basidiomycetous fungi against Groundnut bud necrosis virus in tomato

Tomato is an important vegetable crop which is severely affected by Groundnut bud necrosis virus (GBNV). Until now effective antiviral agents have not been reported for the management of necrosis disease caused by GBNV. Therefore, a study was undertaken to manage the necrosis disease caused by GBNV using culture filtrate of basidiomycetous fungi viz., Coprinopsiscinerea, Ganoderma lucidum and Lentinula edodes. In vitro studies were conducted in the indicator host cowpea and primary host tomato in glasshouse under insect proof condition; co-inoculation spraying of culture filtrate of Ganoderma lucidum at 0.1% concentration reduced the lesion numbers and inhibited the virus population build-up when compared to inoculated control in the indicator host cowpea upto 77.83%. DAC-ELISA test was performed to quantify the virus titre, indicated reduced virus titre in co- inoculation spray of culture filtrate of G. lucidum treated cowpea with OD value 0.17 ± 0.01 at 405 nm and in tomato plants 0.14 ± 0.01 respectively. The viral copy numbers were quantified by qPCR. About 2.0 × 10¹ viral copy numbers were observed in tomato plants treated with G. lucidum (co-inoculation) which was lesser than untreated inoculated control plants (2.4 × 10⁸). In order to identify the antiviral properties of G. lucidum, GCMS analysis was carried out and we found the triterpenoid compound Squalene. This is the first study to analyse and confirm the antiviral activity of G. lucidum against a plant virus.

A Pharmacokinetic and Pharmacodynamic Evaluation of the Anti-Hepatocellular Carcinoma Compound 4-N-Carbobenzoxy-gemcitabine (Cbz-dFdC)

Gemcitabine (dFdC) demonstrates significant effectiveness against solid tumors in vitro and in vivo; however, its clinical application is limited because it tends to easily undergo deamination metabolism. Therefore, we synthesized 4-N-carbobenzoxy-gemcitabine (Cbz-dFdC) as a lead prodrug and conducted a detailed pharmacokinetic, metabolic, and pharmacodynamic evaluation. After intragastric Cbz-dFdC administration, the C_max of Cbz-dFdC and dFdC was 451.1 ± 106.7 and 1656.3 ± 431.5 ng/mL, respectively. The T_max of Cbz-dFdC and dFdC was 2 and 4 h, respectively. After intragastric administration of Cbz-dFdC, this compound was mainly distributed in the intestine due to low carboxylesterase-1 (CES1) activity. Cbz-dFdC is activated by CES1 in both humans and rats. The enzyme kinetic curves were well fitted by the Michaelis–Menten equation in rats’ blood, plasma, and tissue homogenates and S9 of the liver and kidney, as well as human liver S9 and CES1 recombinase. The pharmacodynamic results showed that the Cbz-dFdC have a good antitumor effect in the HepG2 cell and in tumor-bearing mice, respectively. In general, Cbz-dFdC has good pharmaceutical characteristics and is therefore a good candidate for a potential prodrug.

Squalenoyl-gemcitabine/edelfosine nanoassemblies: Anticancer activity in pediatric cancer cells and pharmacokinetic profile in mice

Despite the great advances accomplished in the treatment of pediatric cancers, recurrences and metastases still exacerbate prognosis in some aggressive solid tumors such as neuroblastoma and osteosarcoma. In view of the poor efficacy and toxicity of current chemotherapeutic treatments, we propose a single multitherapeutic nanotechnology-based strategy by co-assembling in the same nanodevice two amphiphilic antitumor agents: squalenoyl-gemcitabine and edelfosine. Homogeneous batches of nanoassemblies were easily formulated by the nanoprecipitation method. Their anticancer activity was tested in pediatric cancer cell lines and pharmacokinetic studies were performed in mice. In vitro assays revealed a synergistic effect when gemcitabine was co-administered with edelfosine. Squalenoyl-gemcitabine/edelfosine nanoassemblies were found to be capable of intracellular translocation in patient-derived metastatic pediatric osteosarcoma cells and showed a better antitumor profile than squalenoyl-gemcitabine nanoassemblies alone. The intravenous administration of this combinatorial nanomedicine in mice exhibited a controlled release behavior of gemcitabine and diminished edelfosine plasma peak concentrations. These findings make it a suitable pre-clinical candidate for childhood cancer therapy.

Small interfering RNA from the lab discovery to patients' recovery

In 1998, the RNA interference discovery by Fire and Mello revolutionized the scientific and therapeutic world. They showed that small double-stranded RNAs, the siRNAs, were capable of selectively silencing the expression of a targeted gene by degrading its mRNA. Very quickly, it appeared that the use of this natural mechanism was an excellent way to develop new therapeutics, due to its specificity at low doses. However, one major hurdle lies in the delivery into the targeted cells, given that the different extracellular and intracellular barriers of the organism coupled with the physico-chemical characteristics of siRNA do not allow an efficient and safe administration. The development of nanotechnologies has made it possible to counteract these hurdles by vectorizing the siRNA in a vector composed of cationic lipids or polymers, or to chemically modify it by conjugation to a molecule. This has enabled the first clinical developments of siRNAs to begin very quickly after their discovery, for the treatment of various acquired or hereditary pathologies. In 2018, the first siRNA-containing drug was approved by the FDA and the EMA for the treatment of an inherited metabolic disease, the hereditary transthyretin amyloidosis. In this review, we discuss the different barriers to the siRNA after systemic administration and how vectorization or chemical modifications lead to avoid it. We describe some interesting clinical developments and finally, we present the future perspectives.

Albumin-driven disassembly of lipidic nanoparticles: the specific case of the squalene-adenosine nanodrug

In the field of nanomedicine, nanostructured nanoparticles (NPs) made of self-assembling prodrugs emerged in the recent years with promising properties. In particular, squalene-based drug nanoparticles have already shown their efficiency through in vivo experiments. However, a complete pattern of their stability and interactions in the blood stream is still lacking. In this work we assess the behavior of squalene-adenosine (SQAd) nanoparticles - whose neuroprotective effect has already been demonstrated in murine models - in the presence of fetal bovine serum (FBS) and of bovine serum albumin (BSA), the main protein of blood plasma. Extensive physicochemical characterizations were performed using Small Angle Neutron Scattering (SANS), cryogenic transmission electron microscopy (Cryo-TEM), circular dichroism (CD), steady-state fluorescence spectroscopy (SSFS) and isothermal titration calorimetry (ITC) as well as in silico by means of ensemble docking simulations with human serum albumin (HSA). Significant changes in the colloidal stability of the nanoparticles in the presence of serum albumin were observed. SANS, CD and SSFS analyses demonstrated an interaction between SQAd and BSA, with a partial disassembly of the nanoparticles in the presence of BSA and the formation of a complex between SQAd and BSA. The interaction free energy of SQAd nanoparticles with BSA derived from ITC experiments, is about -8 kcal mol^-1 which is further supported in silico by ensemble docking simulations. Overall, our results show that serum albumin partially disassembles SQAd nanoparticles by extracting individual SQAd monomers from them. As a consequence, the SQAd nanoparticles would act as a circulating reservoir in the blood stream. The approach developed in this study could be extended to other soft organic nanoparticles.

Overcoming the delivery barrier of oligonucleotide drugs and enhancing nucleoside drug efficiency: The use of nucleolipids

With the rapid development of synthetic technology and biological technology, many nucleic acid-based drugs have entered the clinical trials. However, their inherent disabilities in actively and efficiently penetrating cell membranes still severely restrict their further application. The main drawback of cationic lipids, which have been widely used as nonviral vectors of nucleic acids, is their high cytotoxicity. A series of nucleoside-based or nucleotide-based nucleolipids have been reported in recent years, due to their oligonucleotide delivery capacity and low toxicity in comparison with cationic lipids. Lipophilic prodrugs of nucleoside analogs have extremely similar structures with nucleolipid vectors and are thus helpful for improving the transmembrane ability. This review introduces the progress of nucleolipids and provides new strategies for improving the delivery efficiency of nucleic acid-based drugs, as well as lipophilic prodrugs of nucleosides or nucleotides for antiviral or anticancer therapies.