Squalenoyl nucleoside monophosphate nanoassemblies: new prodrug strategy for the delivery of nucleotide analogues

SARS-CoV-2 and its new variants: a comprehensive review on nanotechnological application insights into potential approaches

SARS-CoV-2 (COVID-19) spreads and develops quickly worldwide as a new global crisis which has left deep socio-economic damage and massive human mortality. This virus accounts for the ongoing outbreak and forces an urgent need to improve antiviral therapeutics and targeted diagnosing tools. Researchers have been working to find a new drug to combat the virus since the outbreak started in late 2019, but there are currently no successful drugs to control the SARS-CoV-2, which makes the situation riskier. Very recently, new variant of SARS-CoV-2 is identified in many countries which make the situation very critical. No successful treatment has yet been shown although enormous international commitment to combat this pandemic and the start of different clinical trials. Nanomedicine has outstanding potential to solve several specific health issues, like viruses, which are regarded a significant medical issue. In this review, we presented an up-to-date drug design strategy against SARS-CoV-2, including the development of novel drugs and repurposed product potentials were useful, and successful drugs discovery is a constant requirement. The use of nanomaterials in treatment against SARS-CoV-2 and their use as carriers for the transport of the most frequently used antiviral therapeutics are discussed systematically here. We also addressed the possibilities of practical applications of nanoparticles to give the status of COVID-19 antiviral systems.

Emerging 2D materials for antimicrobial applications in the pre- and post-pandemic era

Infectious diseases caused by viral or bacterial pathogens are one of the most serious threats to humanity. Moreover, they may lead to pandemics, as we have witnessed severely with the coronavirus disease 2019 (COVID-19). Nanotechnology, including technological developments of nano-sized materials, has brought great opportunities to control the spreading of such diseases. In the family of nano-sized materials, two-dimensional (2D) materials with intrinsic physicochemical properties can efficiently favor antimicrobial activity and maintain a safer environment to protect people against pathogens. For this purpose, they can be used alone or combined for the disinfection process of microbes, antiviral or antibacterial surface coatings, air filtering of medical equipment like face masks, or antimicrobial drug delivery systems. At the same time, they are promising candidates to deal with the issues of conventional antimicrobial approaches such as low efficacy and high cost. This review covers the antiviral or antibacterial activities of 2D materials and highlights their current and possible future applications. Considering their intrinsic properties, 2D materials will become part of the leading antimicrobial technologies for combating future pandemics anytime soon.

Polymeric Materials as Potential Inhibitors Against SARS-CoV-2

Recently discovered SARS-CoV-2 caused a pandemic that triggered researchers worldwide to focus their research on all aspects of this new peril to humanity. However, in the absence of specific therapeutic intervention, some preventive strategies and supportive treatment minimize the viral transmission as studied by some factors such as basic reproduction number, case fatality rate, and incubation period in the epidemiology of viral diseases. This review briefly discusses coronaviruses' life cycle of SARS-CoV-2 in a human host cell and preventive strategies at some selected source of infection. The antiviral activities of synthetic and natural polymers such as chitosan, hydrophobically modified chitosan, galactosylated chitosan, amine-based dendrimers, cyclodextrin, carrageenans, polyethyleneimine, nanoparticles are highlighted in this article. Mechanism of virus inhibition, detection and diagnosis are also presented. It also suggests that polymeric materials and nanoparticles can be effective as potential inhibitors and immunization against coronaviruses which would further develop new technologies in the field of polymer and nanoscience.

Chitosan-Based Nanoparticles Against Viral Infections

Viral infections, in addition to damaging host cells, can compromise the host immune system, leading to frequent relapse or long-term persistence. Viruses have the capacity to destroy the host cell while liberating their own RNA or DNA in order to replicate within additional host cells. The viral life cycle makes it challenging to develop anti-viral drugs. Nanotechnology-based approaches have been suggested to deal effectively with viral diseases, and overcome some limitations of anti-viral drugs. Nanotechnology has enabled scientists to overcome the challenges of solubility and toxicity of anti-viral drugs, and can enhance their selectivity towards viruses and virally infected cells, while preserving healthy host cells. Chitosan is a naturally occurring polymer that has been used to construct nanoparticles (NPs), which are biocompatible, biodegradable, less toxic, easy to prepare, and can function as effective drug delivery systems (DDSs). Furthermore, chitosan is Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (U.S. FDA). Chitosan NPs have been used in drug delivery by the oral, ocular, pulmonary, nasal, mucosal, buccal, or vaginal routes. They have also been studied for gene delivery, vaccine delivery, and advanced cancer therapy. Multiple lines of evidence suggest that chitosan NPs could be used as new therapeutic tools against viral infections. In this review we summarize reports concerning the therapeutic potential of chitosan NPs against various viral infections.

Potential inhibitors of SARS-CoV-2: recent advances

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared in 2019 and is the causative agent of the new pandemic viral disease COVID-19. The outbreak of COVID-19 infection is affecting the entire world, thus many researchers and scientists are desperately looking for suitable vaccines and treatment options. Indeed, researches to find potential inhibitors of SARS-CoV-2 are mainly focussed on targeting virus-host interactions or inhibiting viral assembly. Additionally, drugs and other therapeutic agents that modulate broad-spectrum host innate immune responses or interfere with signalling pathways involved in viral replication are important. These drugs may be capable of engaging host receptors or proteases utilised for viral entry or may impact the endocytosis pathway. 3CL^pro (3-chymotrypsin-like protease), PL^pro (papain-like protease), RdRp (RNA-dependent RNA polymerase), S protein (viral spike glycoprotein), TMPRSS2 (transmembrane protease serine 2), ACE2 (angiotensin-converting enzyme 2), and AT2 (angiotensin AT2 receptor) are important targets. With no approved therapies, this pandemic illustrates the urgent need for safe and broad-spectrum antiviral agents and strategies against SARS-CoV-2 and future pathogenic viruses. In this review, we discussed about the recent trends and important challenges regarding the potential inhibitors, antiviral drugs and nanomaterials screened against SARS-CoV-2.

Nanomaterials and Nanotechnology-Associated Innovations against Viral Infections with a Focus on Coronaviruses

Viral infections have recently emerged not only as a health threat to people but rapidly became the cause of universal fatality on a large scale. Nanomaterials comprising functionalized nanoparticles (NPs) and quantum dots and nanotechnology-associated innovative detection methods, vaccine design, and nanodrug production have shown immense promise for interfacing with pathogenic viruses and restricting their entrance into cells. These viruses have been scrutinized using rapid diagnostic detection and therapeutic interventional options against the caused infections including vaccine development for prevention and control. Coronaviruses, namely SARS-CoV, MERS-CoV, and SARS-CoV-2, have endangered human life, and the COVID-19 (caused by SARS-CoV-2) outbreak has become a perilous challenge to public health globally with huge accompanying morbidity rates. Thus, it is imperative to expedite the drug and vaccine development efforts that would help mitigate this pandemic. In this regard, smart and innovative nano-based technologies and approaches encompassing applications of green nanomedicine, bio-inspired methods, multifunctional bioengineered nanomaterials, and biomimetic drug delivery systems/carriers can help resolve the critical issues regarding detection, prevention, and treatment of viral infections. This perspective review expounds recent nanoscience advancements for the detection and treatment of viral infections with focus on coronaviruses and encompasses nano-based formulations and delivery platforms, nanovaccines, and promising methods for clinical diagnosis, especially regarding SARS-CoV-2.

Recent advances in siRNA delivery mediated by lipid-based nanoparticles

Small interfering RNA (siRNA) has been expected to be a unique pharmaceutic for the treatment of broad-spectrum intractable diseases. However, its unfavorable properties such as easy degradation in the blood and negative-charge density are still a formidable barrier for clinical use. For disruption of this barrier, siRNA delivery technology has been significantly advanced in the past two decades. The approval of Patisiran (ONPATTRO™) for the treatment of transthyretin-mediated amyloidosis, the first approved siRNA drug, is a most important milestone. Since lipid-based nanoparticles (LNPs) are used in Patisiran, LNP-based siRNA delivery is now of significant interest for the development of the next siRNA formulation. In this review, we describe the design of LNPs for the improvement of siRNA properties, bioavailability, and pharmacokinetics. Recently, a number of siRNA-encapsulated LNPs were reported for the treatment of intractable diseases such as cancer, viral infection, inflammatory neurological disorder, and genetic diseases. We believe that these contributions address and will promote the development of an effective LNP-based siRNA delivery system and siRNA formulation.

From poly(alkyl cyanoacrylate) to squalene as core material for the design of nanomedicines

This review article covers the most important steps of the pioneering work of Patrick Couvreur and tries to shed light on his outstanding career that has been a source of inspiration for many decades. His discovery of biodegradable poly(alkyl cyanoacrylate) (PACA) nanoparticles (NPs) has opened large perspectives in nanomedicine. Indeed, NPs made from various types of alkyl cyanoacrylate monomers have been used in different applications, such as the treatment of intracellular infections or the treatment of multidrug resistant hepatocarcinoma. This latest application led to the Phase III clinical trial of Livatag^®, a PACA nanoparticulate formulation of doxorubicin. Despite the success of PACA NPs, the development of a novel type of NP with higher drug loadings and lower burst release was tackled by the discovery of squalene-based nanomedicines where the drug is covalently linked to the lipid derivative and the resulting conjugate is self-assembled into NPs. This pioneering work was accompanied by a wide range of novel applications which mainly dealt with the management of unmet medical needs (e.g. pancreatic cancer, brain ischaemia and spinal cord injury).

A Scalable Method for Squalenoylation and Assembly of Multifunctional 64Cu-Labeled Squalenoylated Gemcitabine Nanoparticles

Squalenoylation of gemcitabine, a front-line therapy for pancreatic cancer, allows for improved cellular-level and system-wide drug delivery. The established methods to conjugate squalene to gemcitabine and to form nanoparticles (NPs) with the squalenoylated gemcitabine (SqGem) conjugate are cumbersome, time-consuming and can be difficult to reliably replicate. Further, the creation of multi-functional SqGem-based NP theranostics would facilitate characterization of in vivo pharmacokinetics and efficacy.

Methods: Squalenoylation conjugation chemistry was enhanced to improve reliability and scalability using tert-butyldimethylsilyl (TBDMS) protecting groups. We then optimized a scalable microfluidic mixing platform to produce SqGem-based NPs and evaluated the stability and morphology of select NP formulations using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Cytotoxicity was evaluated in both PANC-1 and KPC (Kras^LSL-G12D/+; Trp53^LSL-R172H/+; Pdx-Cre) pancreatic cancer cell lines. A ⁶⁴Cu chelator (2-S-(4-aminobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid, NOTA) was squalenoylated and used with positron emission tomography (PET) imaging to monitor the in vivo fate of SqGem-based NPs.

Results: Squalenoylation yields of gemcitabine increased from 15% to 63%. Cholesterol-PEG-2k inclusion was required to form SqGem-based NPs using our technique, and additional cholesterol inclusion increased particle stability at room temperature; after 1 week the PDI of SqGem NPs with cholesterol was ~ 0.2 while the PDI of SqGem NPs lacking cholesterol was ~ 0.5. Similar or superior cytotoxicity was achieved for SqGem-based NPs compared to gemcitabine or Abraxane® when evaluated at a concentration of 10 µM. Squalenoylation of NOTA enabled in vivo monitoring of SqGem-based NP pharmacokinetics and biodistribution.

Conclusion: We present a scalable technique for fabricating efficacious squalenoylated-gemcitabine nanoparticles and confirm their pharmacokinetic profile using a novel multifunctional ⁶⁴Cu-SqNOTA-SqGem NP.

The role of nanotechnology in the treatment of viral infections

Infectious diseases are the leading cause of mortality worldwide, with viruses in particular making global impact on healthcare and socioeconomic development. In addition, the rapid development of drug resistance to currently available therapies and adverse side effects due to prolonged use is a serious public health concern. The development of novel treatment strategies is therefore required. The interaction of nanostructures with microorganisms is fast-revolutionizing the biomedical field by offering advantages in both diagnostic and therapeutic applications. Nanoparticles offer unique physical properties that have associated benefits for drug delivery. These are predominantly due to the particle size (which affects bioavailability and circulation time), large surface area to volume ratio (enhanced solubility compared to larger particles), tunable surface charge of the particle with the possibility of encapsulation, and large drug payloads that can be accommodated. These properties, which are unlike bulk materials of the same compositions, make nanoparticulate drug delivery systems ideal candidates to explore in order to achieve and/or improve therapeutic effects. This review presents a broad overview of the application of nanosized materials for the treatment of common viral infections.

Lipid-Drug Conjugate for Enhancing Drug Delivery

Lipid-drug conjugates (LDCs) are drug molecules that have been covalently modified with lipids. The conjugation of lipids to drug molecules increases lipophilicity and also changes other properties of drugs. The conjugates demonstrate several advantages including improved oral bioavailability, improved targeting to the lymphatic system, enhanced tumor targeting, and reduced toxicity. Based on the chemical nature of drugs and lipids, various conjugation strategies and chemical linkers can be utilized to synthesize LDCs. Linkers and/or conjugation methods determine how drugs are released from LDCs and are critical for the optimal performance of LDCs. In this review, different lipids used for preparing LDCs and various conjugation strategies are summarized. Although LDCs can be administered without a delivery carrier, most of them are loaded into appropriate delivery systems. The lipid moiety in the conjugates can significantly enhance drug loading into hydrophobic components of delivery carriers and thus generate formulations with high drug loading and superior stability. Different delivery carriers such as emulsions, liposomes, micelles, lipid nanoparticles, and polymer nanoparticles are also discussed in this review.

How can nanomedicines overcome cellular-based anticancer drug resistance?

This review discusses the mechanisms of anticancer drug resistance according to its cellular level of action and outlines the nanomedicine-based strategies adopted to overcome it.

Biocatalytic approaches applied to the synthesis of nucleoside prodrugs

Nucleosides are valuable bioactive molecules, which display antiviral and antitumour activities. Diverse types of prodrugs are designed to enhance their therapeutic efficacy, however this strategy faces the troublesome selectivity issues of nucleoside chemistry. In this context, the aim of this review is to give an overview of the opportunities provided by biocatalytic procedures in the preparation of nucleoside prodrugs. The potential of biocatalysis in this research area will be presented through examples covering the different types of nucleoside prodrugs: nucleoside analogues as prodrugs, nucleoside lipophilic prodrugs and nucleoside hydrophilic prodrugs.

Lipid prodrug nanocarriers in cancer therapy

Application of nanotechnology in the medical field (i.e., nanomedicine) plays an important role in the development of novel drug delivery methods. Nanoscale drug delivery systems can indeed be customized with specific functionalities in order to improve the efficacy of the treatments. However, despite the progresses of the last decades, nanomedicines still face important obstacles related to: (i) the physico-chemical properties of the drug moieties which may reduce the total amount of loaded drug; (ii) the rapid and uncontrolled release (i.e., burst release) of the encapsulated drug after administration and (iii) the instability of the drug in biological media where a fast transformation into inactive metabolites can occur. As an alternative strategy to alleviate these drawbacks, the prodrug approach has found wide application. The covalent modification of a drug molecule into an inactive precursor from which the drug will be freed after administration offers several benefits such as: (i) a sustained drug release (mediated by chemical or enzymatic hydrolysis of the linkage between the drug-moiety and its promoiety); (ii) an increase of the drug chemical stability and solubility and, (iii) a reduced toxicity before the metabolization occurs. Lipids have been widely used as building blocks for the design of various prodrugs. Interestingly enough, these lipid-derivatized drugs can be delivered through a nanoparticulate form due to their ability to self-assemble and/or to be incorporated into lipid/polymer matrices. Among the several prodrugs developed so far, this review will focus on the main achievements in the field of lipid-based prodrug nanocarriers designed to improve the efficacy of anticancer drugs. Gemcitabine (Pubchem CID: 60750); 5-fluorouracil (Pubchem CID: 3385); Doxorubicin (Pubchem CID: 31703); Docetaxel (Pubchem CID: 148124); Methotrexate (Pubchem CID: 126941); Paclitaxel (Pubchem CID: 36314).

"Squalenoylcurcumin" nanoassemblies as water-dispersible drug candidates with antileishmanial activity

Curcumin, a natural polyphenolic compound, showed antiparasitic potential, including trypanocidal and leishmanicidal activity, in several in vitro and in vivo models. The molecule is well tolerated in humans. However, it is insoluble in water and displays poor oral bioavailability as a result of low absorption. New derivatives of curcumin were prepared by esterification of one or two of its phenolic groups with 1,1',2-tris-norsqualenic acid. These "squalenoylcurcumins" were formulated as water-dispersible nanoassemblies of homogeneous size, and they proved to be stable. Squalenoylcurcumins were inactive against Trypanosoma brucei brucei trypomastigotes, even as nanoassemblies, in contrast with curcumin. However, against Leishmania donovani promastigotes, the activities of the squalenoylcurcumins and their nanoassemblies were enhanced relative to that of curcumin. In L. donovani axenic and intramacrophagic amastigotes, they showed activity in the range of miltefosine, with good selectivity indexes. In regard to their dispersibility in water and to the safety of curcumin, these nanoassemblies are promising candidates for preclinical study toward the treatment of visceral leishmaniasis.

Gemcitabine-based therapy for pancreatic cancer using the squalenoyl nucleoside monophosphate nanoassemblies

Gemcitabine is currently the most effective agent against advanced pancreatic cancer. However, the major therapeutic hurdles using gemcitabine include rapid inactivation by blood deaminases and fast development of cell chemoresistance, induced by down-regulation of deoxycytidine kinase or nucleoside transporters. To overcome the above drawbacks we designed recently a novel nanomedicine strategy based on squalenoyl prodrug of 5'-monophosphate gemcitabine (SQdFdC-MP). This amphiphilic conjugate self-organized in water into unilamellar vesicles with a mean diameter of 100 nm. In this study the antitumor efficacy of SQdFdC-MP nanoassemblies (NAs) on chemoresistant and chemosensitive pancreatic adenocarcinoma models have been investigated. Cell viability assays showed that SQdFdC-MP NAs displayed higher antiproliferative and cytotoxic effects, particularly in chemoresistant pancreatic tumor cells. In in vivo studies, SQdFdC-MP NAs decreased significantly the growth (∼70%) of human MiaPaCa2 xenografts, also preventing tumor cell invasion, whereas native dFdC did not display any anticancer activity when tumor growth inhibition was only 35% with SQdFdC NAs. These results correlated with a reduction of Ki-67 antigen and the induction of apoptosis mediated by caspase-3 activation in tumor cells. These findings demonstrated the feasibility of utilizing SQdFdC-MP NAs to make tumor cells more sensitive to gemcitabine and thus providing an efficient new therapeutic alternative for pancreatic adenocarcinoma.

Synthesis, properties, and biological activity of boranophosphate analogs of the mRNA cap: versatile tools for manipulation of therapeutically relevant cap-dependent processes

Modified mRNA cap analogs aid in the study of mRNA-related processes and may enable creation of novel therapeutic interventions. We report the synthesis and properties of 11 dinucleotide cap analogs bearing a single boranophosphate modification at either the α-, β- or γ-position of the 5',5'-triphosphate chain. The compounds can potentially serve either as inhibitors of translation in cancer cells or reagents for increasing expression of therapeutic proteins in vivo from exogenous mRNAs. The BH3-analogs were tested as substrates and binding partners for two major cytoplasmic cap-binding proteins, DcpS, a decapping pyrophosphatase, and eIF4E, a translation initiation factor. The susceptibility to DcpS was different between BH3-analogs and the corresponding analogs containing S instead of BH3 (S-analogs). Depending on its placement, the boranophosphate group weakened the interaction with DcpS but stabilized the interaction with eIF4E. The first of the properties makes the BH3-analogs more stable and the second, more potent as inhibitors of protein biosynthesis. Protein expression in dendritic cells was 2.2- and 1.7-fold higher for mRNAs capped with m2 (7,2'-O)GppBH3pG D1 and m2 (7,2'-O)GppBH3pG D2, respectively, than for in vitro transcribed mRNA capped with m2 (7,3'-O)GpppG. Higher expression of cancer antigens would make mRNAs containing m2 (7,2'-O)GppBH3pG D1 and m2 (7,2'-O)GppBH3pG D2 favorable for anticancer immunization.

Rational design for multifunctional non-liposomal lipid-based nanocarriers for cancer management: theory to practice

Nanomedicines have gained more and more attention in cancer therapy thanks to their ability to enhance the tumour accumulation and the intracellular uptake of drugs while reducing their inactivation and toxicity. In parallel, nanocarriers have been successfully employed as diagnostic tools increasing imaging resolution holding great promises both in preclinical research and in clinical settings. Lipid-based nanocarriers are a class of biocompatible and biodegradable vehicles that provide advanced delivery of therapeutic and imaging agents, improving pharmacokinetic profile and safety. One of most promising engineering challenges is the design of innovative and versatile multifunctional targeted nanotechnologies for cancer treatment and diagnosis. This review aims to highlight rational approaches to design multifunctional non liposomal lipid-based nanocarriers providing an update of literature in this field.

Nanotechnology and the treatment of HIV infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals.