A mechanistic approach for the optimization of loperamide loaded nanocarriers characterization: Diafiltration and mathematical modeling advantages

Purification processes of polymeric nanoparticles: How to improve their clinical translation?

Polymeric nanoparticles, as revolutionary nanomedicines, have offered a new class of diagnostic and therapeutic solutions for a multitude of diseases. With its immense potential, the world witnesses the new age of nanotechnology after the COVID-19 vaccines were developed based on nanotechnology. Even though there are countless benchtop research studies in the nanotechnology world, their integration into commercially available technologies is still restricted. The post-pandemic world demands a surge of research in the domain, which leaves us with the fundamental question: why is the clinical translation of therapeutic nanoparticles so restricted? Complications in nanomedicine purification, among other things, are to blame for the lack of transference. Polymeric nanoparticles, owing to their ease of manufacture, biocompatibility, and enhanced efficiency, are one of the more explored domains in organic-based nanomedicines. Purification of nanoparticles can be challenging and necessitates tailoring the available methods in accordance with the polymeric nanoparticle and impurities involved. Though a number of techniques have been described, there are no available guidelines that help in selecting the method to better suit our requirements. We encountered this difficulty while compiling articles for this review and looking for methods to purify polymeric nanoparticles. The currently accessible bibliography for purification techniques only provides approaches for a specific type of nanomaterial or sometimes even procedures for bulk materials, that are not fully relevant to nanoparticles. In our research, we tried to summarize the available purification techniques using the approach of A.F. Armington. We divided the purification systems into two major classes, namely: phase separation-based techniques (based on the physical differences between the phases) and matter exchange-based techniques (centered on physicochemical induced transfer of materials and compounds). The phase separation methods are based on either using nanoparticle size differences to retain them on a physical barrier (filtration techniques) or using their densities to segregate them (centrifugation techniques). The matter exchange separation methods rely on either transferring the molecules or impurities across a barrier using simple physicochemical phenomena, like the concentration gradients (dialysis method) or partition coefficients (extraction technique). After describing the methods in detail, we highlight their advantages and limitations, mainly focusing on preformed polymer-based nanoparticles. Tailoring a purification strategy takes into account the nanoparticle structure and its integrity, the method selected should be suited for preserving the integrity of the particles, in addition to conforming to the economical, material and productivity considerations. In the meantime, we advocate the use of a harmonized international regulatory framework to define the adequate physicochemical and biological characterization of nanomedicines. An appropriate purification strategy serves as the backbone to achieving desired characteristics, in addition to reducing variability. As a result, the present review aspires to serve as a comprehensive guide for researchers, who are new to the domain, as well as a synopsis of purification strategies and analytical characterization methods used in preclinical studies.

β-Cyclodextrin-Based Nanosponges Inclusion Compounds Associated with Gold Nanorods for Potential NIR-II Drug Delivery

This article describes the synthesis and characterization of two nanocarriers consisting of β-cyclodextrin-based nanosponges (NSs) inclusion compounds (ICs) and gold nanorods (AuNRs) for potential near-infrared II (NIR-II) drug-delivery systems. These nanosystems sought to improve the stability of two drugs, namely melphalan (MPH) and curcumin (CUR), and to trigger their photothermal release after a laser irradiation stimulus (1064 nm). The inclusion of MPH and CUR inside each NS was confirmed by field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, Fourier transform infrared spectroscopy, (FT-IR) differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and proton nuclear magnetic resonance (1H-NMR). Furthermore, the association of AuNRs with both ICs was confirmed by FE-SEM, energy-dispersive spectroscopy (EDS), TEM, dynamic light scattering (DLS), ζ-potential, and UV–Vis. Moreover, the irradiation assays demonstrated the feasibility of the controlled-photothermal drug release of both MPH and CUR in the second biological window (1000–1300 nm). Finally, MTS assays depicted that the inclusion of MPH and CUR inside the cavities of NSs reduces the effects on mitochondrial activity, as compared to that observed in the free drugs. Overall, these results suggest the use of NSs associated with AuNRs as a potential technology of controlled drug delivery in tumor therapy, since they are efficient and non-toxic materials.

Eucalyptol/ β-cyclodextrin inclusion complex loaded gellan/PVA nanofibers as antifungal drug delivery system

Fungal infections pose a serious threat to humankind due to the toxicity of conventional antifungal therapy and continuous emerging incidence of multidrug resistance. Essential oils fascinated researchers because of their broad antimicrobial activity and minimal cytotoxicity. However, hydrophobic, volatile and low water solubility of essential oils hinder their applications in pharmaceutical industries. Therefore, in this study we have loaded eucalyptol/ β-cyclodextrin inclusion complex to gellan/polyvinyl alcohol nanofibers (EPNF) to eradicate Candida albicans and Candida glabrata biofilms. The electrospun nanofibers characterized by various physicochemical techniques and it was observed that EPNF possess highly hydrophilic surface property that facilitate rapid drug release. EPNF inhibited approximately 70% biofilm of C. albicans and C. glabrata. Time kill results depicted that eucalyptol (EPTL) encapsulation in the nanofibers prolonged its antifungal activity than the pure EPTL. Electron microscopy studies revealed that EPNF disrupted the cell surface of Candida. Collectively the current study suggested nanofiber encapsulation enhanced antibiofilm activity of eucalyptol and these nanoscale systems can serve as an alternative therapeutic strategy to treat fungal infections. Further, the developed nanofibrous materials can be applied as cost effective coating agent for biomedical implants.

A systematic study to unravel the potential of using polysaccharides based organic-nanoparticles versus hybrid-nanoparticles for pesticide delivery

To daze conventional pesticide release limitations, nanotechnology-mediated pesticide delivery using natural polymers has been actively investigated. However, the lack of information on what are the beneficial/non-beneficial aspects of using hybrid- and organic-nanoparticles (NP) and among the polysaccharides which are better suited concerning pesticide loading efficiency (PLE wt%), entrapment efficiency, and sustained pesticide release (SPR %) has prompted us to investigate this study. In this report, we systematically investigated a series of polysaccharides such as starch (S), cellulose (C), aminocellulose (AC), and sodium carboxymethylcellulose (NaCMC) coated on magnetite NP (MNP, Fe₃O₄) and complete organic nanocarrier systems (starch and cellulose) that have no MNP part were compared for the PLE wt% and SPR % efficiencies for chlorpyrifos (ChP) insecticide. Overall, all nanocarriers (NCs) have shown good to excellent PLE wt% due to the smaller-sized NP obtained through optimal conditions. However, among the hybrid polysaccharides studied, starch MNP has shown a maximum PLE of 111 wt% in comparison with other polysaccharides (80-94 wt%) coated hybrid-NCs as well as with organic-NCs (81-87 wt%). The use of inorganic support does improve the PLE wt% markedly for starch but not for cellulose derivatives. Similarly, the SPR results of S-NP showed a remarkably better sustained release profile for ChP of 88% in 14 d. In contrast, other unfunctionalized and functionalized celluloses exhibited poor release profiles of 60%-20% for the same period. This study may help the researchers choose the right system for designing and achieving enhanced pesticide efficiency.

The key role of the drug self-aggregation ability to obtain optimal nanocarriers based on aromatic-aromatic drug-polymer interactions

The efficient association and controlled release of hydrophilic and aromatic low molecular-weight drugs (HALMD) still remains a challenge due to their relatively weak interactions with excipients and strong affinity to water. Considering that a wide variety of drugs to treat chronic diseases are HALMD, their inclusion in polymeric nanoparticles (NPs) constitutes an attractive possibility by providing to these drugs with controllable physiochemical properties, preventing crisis episodes, decreasing dose-dependent side effects and promoting therapeutic adhesiveness. However, the strong interaction of HALMD with the aqueous medium jeopardizes their encapsulation and controlled release. In this work, the role of the self-assembly tendency of HALMD on their association with the aromatic excipient poly(sodium 4-styrensulfonate) (PSS) to form NPs is studied. For this aim, the widely used drugs amitriptyline (AMT), promethazine (PMZ), and chlorpheniramine (CPM) are selected due to their well described critical aggregation concentration (cac) (36 mM for AMT, 36 mM for PMZ, and 69.5 mM for CPM). These drugs undergo aromatic-aromatic interactions with the polymer, which stabilize their mutual binding, as seen by NMR. The simple mixing of solutions of opposite charged molecules (drug + PSS) allowed obtaining NPs. Importantly, comparing the three drugs, the formation of NPs occurred at significantly lower absolute concentration and significantly lower drug/polymer ratio as the cac takes lower values, indicating a stronger binding to the polymer, as also deduced from the respective drug/polymer dissociation constant values. In addition, the number of formed NPs is similar for all formulations, even though a much lower concentration of the drug and polymer is present in systems comprising lower cac. The obtained NPs are spheroidal and present size between 100 and 160 nm, low polydispersity (≤0.3) and negative zeta potential (from -30 to -60 mV). The association efficiency reaches values ≥ 83% and drug loading could achieve values up to 68% (never evidenced before for systems comprising HALMD). In addition, drug release studies are also significantly influenced by cac, providing more prolonged release for AMT and PMZ (lower cac), whose delivery profiles adjust to the Korsmeyer-Peppas equation. As a novelty of this work, a synergic contribution of drug self-association tendency and aromatic-aromatic interaction between the drug and polymers is highlighted, a fact that could be crucial for the rational design and development of efficient drug delivery systems.

Poloxamer 188-Coated Ammonium Methacrylate Copolymer Nanocarriers Enhance Loperamide Permeability across Pgp-Expressing Epithelia

Loperamide is a μ-opioid agonist with poor gastrointestinal absorption, mainly because of its modest aqueous solubility and being a P-glycoprotein (Pgp) efflux substrate. Nevertheless, studies associated with therapeutic effects strongly suggest that loperamide holds potential pharmacological advantages over traditional μ-opioid agonists commonly used for analgesia. Thus, in this Communication, we assessed in MDCK-hMDR1 cell lines the effects over loperamide uptake and efflux ratio, when loaded into Eudragit RS (ERS) nanocarriers coated with poloxamer 188 (P188). ERS was chosen for enhancing loperamide aqueous dispersibility and P188 as a potential negative Pgp modulator. In uptake assays, it was observed that Pgp limited the accumulation of loperamide into cells and that preincubation with P188, but not coincubation, led to increasing loperamide uptake at a similar extent of Pgp pharmacological inhibition. On the other hand, the efflux ratio displayed no alterations when Pgp was pharmacologically inhibited, whereas ERS/P188 nanocarriers effectively enhanced loperamide uptake and absorptive transepithelial transport. The latter suggests that loperamide transport across cells is significantly influenced by the presence of the unstirred water layer (UWL), which could hinder the visualization of Pgp-efflux effects during transport assays. Thus, results in this work highlight that formulating loperamide into this nanocarrier enhances its uptake and transport permeability.