Characterisation and quantification of liposome-type nanoparticles in a beverage matrix using hydrodynamic chromatography and MALDI–TOF mass spectrometry

Recent developments in the use of nanocrystals to improve bioavailability of APIs

Nanocrystals refer to materials with at least one dimension smaller than 100 nm, composing of atoms arranged in single crystals or polycrystals. Nanocrystals have significant research value as they offer unique advantages over conventional pharmaceutical formulations, such as high bioavailability, enhanced targeting selectivity and controlled release ability and are therefore suitable for the delivery of a wide range of drugs such as insoluble drugs, antitumor drugs and genetic drugs with broad application prospects. In recent years, research on nanocrystals has been progressively refined and new products have been launched or entered the clinical phase of studies. However, issues such as safety and stability still stand that need to be addressed for further development of nanocrystal formulations, and significant gaps do exist in research in various fields in this pharmaceutical arena. This paper presents a systematic overview of the advanced development of nanocrystals, ranging from the preparation approaches of nanocrystals with which the bioavailability of poorly water-soluble drugs is improved, critical properties of nanocrystals and associated characterization techniques, the recent development of nanocrystals with different administration routes, the advantages and associated limitations of nanocrystal formulations, the mechanisms of physical instability, and the enhanced dissolution performance, to the future perspectives, with a final view to shed more light on the future development of nanocrystals as a means of optimizing the bioavailability of drug candidates. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Luminescence continuous flow system for monitoring the efficiency of hybrid liposomes separation using multiphase density gradient centrifugation

A method for monitoring the efficiency of the hybrid magnetoliposomes (h-MLs) separation using multiphase density gradient centrifugation (MDGC) coupled with a continuous flow system (CFS) is described. Several h-MLs suspensions containing hydrophobic magnetic gold nanoparticles (Fe₃O₄@AuNPs-C12SH) and different fluorophores encapsulated have been synthesized using the rapid solvent evaporation (RSE) method. The MDGC system was prepared using a non-linear multiphase density gradient formed with a bottom layer with 100% (v/v) sucrose solution and six layers containing a mixture of sucrose solution (with concentrations ranged between 10 and 55% v/v), and fixed concentrations of ficoll (30% v/v) and percoll (15% v/v) solutions. The density gradient profile was previously stabilized using a relative centrifugal force (RCF) of 4480×g for 30 min. The synthesized h-MLs were added to the density gradient profile and separated by centrifugation at 2520×g for 20 min. The efficiency of the separation procedure was tested, aspirating the separated extract into the CFS and lysing liposomes before their translation to the detector introducing surfactant solutions. The luminescence signals provided by the release of the encapsulated fluorophores and other materials provided the distribution status of the liposomes in each density gradient stage. The monitoring of the different samples revealed four different fractions (MLs, h-Ls, h-MLs, and non-encapsulated fluorophores) for each separated h-MLs. Additional information on the h-MLs has also been acquired by confocal microscopy.

Tackling Complex Analytical Tasks: An ISO/TS-Based Validation Approach for Hydrodynamic Chromatography Single Particle Inductively Coupled Plasma Mass Spectrometry

Nano-carrier systems such as liposomes have promising biomedical applications. Nevertheless, characterization of these complex samples is a challenging analytical task. In this study a coupled hydrodynamic chromatography-single particle-inductively coupled plasma mass spectrometry (HDC-spICP-MS) approach was validated based on the technical specification (TS) 19590:2017 of the international organization for standardization (ISO). The TS has been adapted to the hyphenated setup. The quality criteria (QC), e.g., linearity of the calibration, transport efficiency, were investigated. Furthermore, a cross calibration of the particle size was performed with values from dynamic light scattering (DLS) and transmission electron microscopy (TEM). Due to an additional Y-piece, an online-calibration routine was implemented. This approach allows the calibration of the ICP-MS during the dead time of the chromatography run, to reduce the required time and enhance the robustness of the results. The optimized method was tested with different gold nanoparticle (Au-NP) mixtures to investigate the characterization properties of HDC separations for samples with increasing complexity. Additionally, the technique was successfully applied to simultaneously determine both the hydrodynamic radius and the Au-NP content in liposomes. With the established hyphenated setup, it was possible to distinguish between different subpopulations with various NP loads and different hydrodynamic diameters inside the liposome carriers.

Silencing SOCS1 via Liposome-Packed siRNA Sustains TLR4-Ligand Adjuvant

Infectious diseases remain one of the leading causes of death worldwide. Vaccination is a powerful instrument to avert a variety of those by inducing a pathogen-specific immune response and ensure a long-lasting protection against the respective infection. Nevertheless, due to increasing numbers of immunocompromised patients and emergence of more aggressive pathogens existing vaccination techniques are limited. In our study we investigated a new strategy to strengthen vaccine adjuvant in order to increase immunity against infectious diseases. The strategy is based on an amplification of Toll-like receptor 4 (TLR4) -induced activation of antigen-presenting cells (APCs) by turning off a powerful endogenous inhibitor of APC-activation. TLR4 signaling induces the release of cytokines that bind autocrine and paracrine to receptors, activating the Janus kinase (JAK) 2/signal transducers and activators of transcription (STAT) 3 cascade. Subsequently, STAT3 induces expression of suppressor of cytokine signaling (SOCS) 1 that terminates the inflammatory response. In the approach, TLR4-adjuvant monophosphoryl lipid A (MPLA)-stimulated monocyte-activation is reinforced and sustained by silencing SOCS1 via lipid nanoparticle-enclosed siRNA (L-siRNA). L-siRNA is transported into primary cells without any toxic side effects and protected from early degradation. Through lipid core-embedded functional groups the lipid particle escapes from endosomes and releases the siRNA when translocated into the cytoplasm. SOCS1 is potently silenced, and SOCS1-mediated termination of NFκB signaling is abrogated. Consequently, the MPLA-stimulated activation of APCs, monitored by release of pro-inflammatory cytokines such as IL-6, TNFα, and IL-1β, upregulation of MHC class II molecules and costimulatory CD80/CD86 is strongly enhanced and prolonged. SOCS1-silenced APCs, pulsed with liposomal tetanus light chain toxin (TeTxLC) antigen, activate autologous T cells much more intensively than SOCS1-expressing cells. Importantly, expansion of cocultured CD4⁺ as well as CD8⁺ T cells is remarkably enhanced. Furthermore, our results point toward a broad T helper cell response as TH1 typical as well as TH2 characteristic cytokines are elevated. Taken together, this study in the human system comprises a translational potential to develop more effective vaccines against infectious diseases by inhibition of the endogenous negative-feedback loop in APCs.

Study of the presence of micro- and nanoparticles in drinks and foods by multiple analytical techniques

A variety of food and drink samples (n = 21) were analyzed to evaluate the presence of (nano-) particles in their composition. After assessment of the sample pre-treatment step, a fast screening analysis was performed for drinks by Dynamic Light Scattering showing particles from 10 to 300 nm that could correspond to organic or metallic NPs. Metallic NPs were identified in foods by Single-Particle mode Inductively Coupled Plasma Mass Spectrometry and Asymmetrical Flow Field-Flow Fractionation coupled to Multiangle Laser Light Scattering and Inductively-Coupled Plasma Mass Spectrometry. The determination of Ti, Si and Ag concentration in the initial food suspensions, after filtration and centrifugal ultrafiltration enabled to estimate the ionic and nanoparticles content. Si-containing particles can be present in cappuccino powder as large aggregates and Si- and Al-containing particles in hot chocolate. Ti-containing NPs (80-200 nm) were found in chewing gum and Ag NPs in silver pearls (50-150 nm) used for decoration pastry.

Nanomaterials in Food Products: A New Analytical Challenge

This chapter focuses on the problem of detecting, characterizing, and determining the concentration of nanomaterials in foods and other biological matrices. After providing an overview of the unique challenges associated with nanoparticle metrology in complex media, sample pretreatment methods (including extraction, digestion, and inline chromatographic separation), imaging analysis, and nanomaterial quantification methods are presented in detail. The chapter also addresses numerous methods under development, including atmospheric scanning electron microscopy, single-particle inductively coupled plasma mass spectrometry, immunological detection methods, and optical techniques such surface plasmon resonance. The chapter concludes with an overview of the research needs in this area.

Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

Seven commercial titanium dioxide pigments and two other well-defined TiO₂ materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry (ICPMS) for chemical characterization. The aF4-ICPMS conditions were optimised and validated for linearity, limit of detection, recovery, repeatability and reproducibility, all indicating good performance. Multi-element detection with aF4-ICPMS showed that some commercial pigments contained zirconium co-eluting with titanium in aF4. The other two TiMs, NM103 and NM104, contained aluminium as integral part of the titanium peak eluting in aF4. The materials were characterised using various size determination techniques: retention time in aF4, aF4 hyphenated with multi-angle laser light spectrometry (MALS), single particle ICPMS (spICPMS), scanning electron microscopy (SEM) and particle tracking analysis (PTA). PTA appeared inappropriate. For the other techniques, size distribution patterns were quite similar, i.e. high polydispersity with diameters from 20 to >700 nm, a modal peak between 200 and 500 nm and a shoulder at 600 nm. Number-based size distribution techniques as spICPMS and SEM showed smaller modal diameters than aF4-UV, from which mass-based diameters are calculated. With aF4-MALS calculated, light-scattering-based “diameters of gyration” (Øg) are similar to hydrodynamic diameters (Øh) from aF4-UV analyses and diameters observed with SEM, but much larger than with spICPMS. A Øg/Øh ratio of about 1 indicates that the TiMs are oblate spheres or fractal aggregates. SEM observations confirm the latter structure. The rationale for differences in modal peak diameter is discussed.

Use of aminothiophenol as an indicator for the analysis of silver nanoparticles in consumer products by surface-enhanced Raman spectroscopy

Silver nanoparticles (Ag NPs) are one of the top five engineered nanoparticles that have been used in various products. Current methods for the measurement of Ag NPs are time consuming and expensive. Therefore, it is of critical importance to develop novel strategies to detect the presence of Ag NPs at low concentrations in different matrices. This study aimed at detecting and measuring Ag NPs in consumer products using surface-enhanced Raman spectroscopy (SERS) coupled with aminothiophenol (PATP) as an indicator molecule that binds strongly with Ag NPs. Quantification and qualification of Ag NPs were achieved using this method of acquiring SERS signals from Ag NP-PATP complexes. Four dietary supplement products and one nasal spray were selected to evaluate the performance of SERS in the detection of Ag NPs. Inductively coupled plasma optical emission spectrometry (ICP-OES) and transmission electron microscopy (TEM) were utilized to measure the physical properties of Ag NPs in the samples. The results demonstrate that distinctive Raman peaks of PATP can be used to distinguish Ag NPs from silver bulk particles and silver nitrate. SERS is able to detect Ag NPs with different sizes ranging from 20 to 100 nm, with the highest intensity for ∼30 nm Ag NPs. A partial least squares method was used to develop quantitative models for the analysis of spectral data (R = 0.94). These results indicate that the conjugation of Ag NPs with PATP can be measured by SERS. These results demonstrate that SERS is a simple and rapid method and has great potential to detect Ag NPs in various products.

Potential Health Impact of Environmentally Released Micro- and Nanoplastics in the Human Food Production Chain: Experiences from Nanotoxicology

High concentrations of plastic debris have been observed in the oceans. Much of the recent concern has focused on microplastics in the marine environment. Recent studies of the size distribution of the plastic debris suggested that continued fragmenting of microplastics into nanosized particles may occur. In this review we assess the current literature on the occurrence of environmentally released micro- and nanoplastics in the human food production chain and their potential health impact. The currently used analytical techniques introduce a great bias in the knowledge, since they are only able to detect plastic particles well above the nanorange. We discuss the potential use of the very sensitive analytical techniques that have been developed for the detection and quantification of engineered nanoparticles. We recognize three possible toxic effects of plastic particles: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics. The limited data on microplastics in foods do not predict adverse effect of these pollutants or additives. Potential toxic effects of microplastic particles will be confined to the gut. The potential human toxicity of nanoplastics is poorly studied. Based on our experiences in nanotoxicology we prioritized future research questions.

Measurement Methods to Detect, Characterize, and Quantify Engineered Nanomaterials in Foods

This article is one of a series of 4 that reports on a task of the NanoRelease Food Additive project of the International Life Science Institute Center for Risk Science Innovation and Application to identify, evaluate, and develop methods that are needed to confidently detect, characterize, and quantify intentionally produced engineered nanomaterials (ENMs) released from food along the alimentary tract. This particular article focuses on the problem of detecting ENMs in food, paying special attention to matrix interferences and how to deal with them. In this review, an in-depth analysis of the literature related to detection of ENMs in complex matrices is presented. The literature review includes discussions of sampling methods, such as centrifugation and ENM extraction. Available analytical methods, as well as emerging methods, are also presented. The article concludes with a summary of findings and an overview of potential knowledge gaps and targets for method development in this area.

Analytical strategies for controlling polysorbate-based nanomicelles in fruit juice

This study focused on the detection and quantification of organic micelle-type nanoparticles (NPs) with polysorbate components (polysorbate 20 and polysorbate 80) in their micelle shells that could be used to load biologically active compounds into fruit juice. Several advanced analytical techniques were applied in the stepwise method development strategy used. In the first phase, a system consisting of ultrahigh-performance liquid chromatography employing a size exclusion column coupled with an evaporative light scattering detector (UHPLC-SEC-ELSD) was used for the fractionation of micelle assemblies from other, lower molecular weight sample components. The limit of detection (LoD) of these polysorbate micelles in spiked apple juice was 500 μg mL(-1). After this screening step, mass spectrometric (MS) detection was utilized to confirm the presence of polysorbates in the detected micelles. Two alternative MS techniques were tested: (i) ambient high-resolution mass spectrometry employing a direct analysis in real time ion source coupled with an Orbitrap MS analyzer (DART-Orbitrap MS) enabled fast and simple detection of the polysorbates present in the samples, with a lowest calibration level (LCL) of 1000 μg mL(-1); (ii) ultrahigh-performance reversed-phase liquid chromatography coupled with high-resolution time-of-flight mass spectrometry (UHPLC-HRTOF-MS) provided highly selective and sensitive detection and quantification of polysorbates with an LCL of 0.5 μg mL(-1).

Development and validation of single particle ICP-MS for sizing and quantitative determination of nano-silver in chicken meat

The application of nanomaterials is leading to innovative developments in industry, agriculture, consumer products, and food and related sectors. However, due to the special properties of these materials there are concerns about their safety, especially because of our limited knowledge of human health effects and the fact that constantly new nanomaterials and applications thereof are being produced. The development of analytical techniques is a key element to understand the benefits as well as the risks of the application of such materials. In this study, a method is developed and validated for sizing and quantifying nano-silver in chicken meat using single particle inductive coupled plasma mass spectrometry (ICP-MS). Samples are processed using an enzymatic digestion followed by dilution of the digest and instrumental analysis of the diluted digest using single particle ICP-MS. Validation of the method in the concentration of 5-25 mg/kg 60-nm silver nanoparticles showed good performance with respect to trueness (98-99% for size, 91-101% for concentration), repeatability (<2% for size, <11% for concentration), and reproducibility (<6% for size, <16% for concentration). The response of the method is linear, and a detection limit as low as 0.1 mg/kg can be obtained. Additional experiments showed that the method is robust and that digests are stable for 3 weeks at 4 °C. Once diluted for single particle ICP-MS analysis, the stability is limited. Finally, it was shown that nano-silver in chicken meat is not stable. Silver nanoparticles dissolved and were transformed into silver sulfide. While this has implications for the form in which nano-silver will be present in real-life meat samples, the developed method will be able to determine the presence and quantity of nanoparticle silver in such samples.