Tunable resistive pulse sensing: potential applications in nanomedicine

In-situ detection of microplastics in the aquatic environment: A systematic literature review

Microplastics are ubiquitous in the aquatic environment and have emerged as a significant environmental issue due to their potential impacts on human health and the ecosystem. Current laboratory-based microplastic detection methods suffer from various drawbacks, including a lack of standardisation, limited spatial and temporal coverage, high costs, and time-consuming procedures. Consequently, there is a need for the development of in-situ techniques to detect and monitor microplastics to effectively identify and understand their sources, pathways, and behaviours. Herein, we adopt a systematic literature review method to assess the development and application of experimental and field technologies designed for the in-situ detection and monitoring of aquatic microplastics, without the need for sample preparation. Four scientific databases were searched in March 2023, resulting in a review of 62 relevant studies. These studies were classified into seven sensor categories and their working principles were discussed. The sensor classes include optical devices, digital holography, Raman spectroscopy, other spectroscopy, hyperspectral imaging, remote sensing, and other methods. We also looked at how data from these technologies are integrated with machine learning models to develop classifiers capable of accurately characterising the physical and chemical properties of microplastics and discriminating them from other particles. This review concluded that in-situ detection of microplastics in aquatic environments is feasible and can be achieved with high accuracy, even though the methods are still in the early stages of development. Nonetheless, further research is still needed to enhance the in-situ detection of microplastics. This includes exploring the possibility of combining various detection methods and developing robust machine-learning classifiers. Additionally, there is a recommendation for in-situ implementation of the reviewed methods to assess their effectiveness in detecting microplastics and identify their limitations.

Analytical techniques for the characterization of nanoparticles for mRNA delivery

Nanotechnology-assisted RNA delivery has gotten a tremendous boost over the last decade and made a significant impact in the development of life-changing vaccines and therapeutics. With increasing numbers of emerging lipid- and polymer-based RNA nanoparticles progressing towards the clinic, it has become apparent that the safety and efficacy of these medications depend on the comprehensive understanding of their critical quality attributes (CQAs). However, despite the rapid advancements in the field, the identification and reliable quantification of CQAs remain a significant challenge. To support these efforts, this review aims to summarize the present knowledge on CQAs based on the regulatory guidelines and to provide insights into the available analytical characterization techniques for RNA-loaded nanoparticles. In this context, routine and emerging analytical techniques are categorized and discussed, focusing on the operation principle, strengths, and potential limitations. Furthermore, the importance of complementary and orthogonal techniques for the measurement of CQAs is discussed in order to ensure the quality and consistency of analytical methods used, and address potential technique-based differences.

Potential Druggability of Mesenchymal Stem/Stromal Cell-derived Exosomes

Exosomes secreted by mesenchymal stem/stromal cells (MSC-Exos) are advantageous candidate sources for novel acellular therapy. Despite the current standards of good manufacturing practice (GMP), the deficiency of suitable quality-control methods and the difficulties in large-scale preparation largely restrict the development of therapeutic products and their clinical applications worldwide. Herein, we mainly focus on three dominating issues commonly encountered in exosomal GMP, including issues upstream of the cell culture process, downstream of the purification process, exosomes quality control, and the drug properties of exosomes and their druggability from a corporate perspective. Collectively, in this review article, we put forward the issues of preparing clinical exosome drugs for the treatment of diverse diseases and provide new references for the clinical application of GMP-grade MSC-Exos.

Rapid Detection of Microparticles Using a Microfluidic Resistive Pulse Sensor Based on Bipolar Pulse-Width Multiplexing

Rapid and accurate analysis of micro/nano bio-objects (e.g., cells, biomolecules) is crucial in clinical diagnostics and drug discovery. While a traditional resistive pulse sensor can provide multiple kinds of information (size, count, surface charge, etc.) about analytes, it has low throughput. We present a unique bipolar pulse-width, multiplexing-based resistive pulse sensor for high-throughput analysis of microparticles. Signal multiplexing is enabled by exposing the central electrode at different locations inside the parallel sensing channels. Together with two common electrodes, the central electrode encodes the electrical signal from each sensing channel, generating specific bipolar template waveforms with different pulse widths. Only one DC source is needed as input, and only one combined electrical output is collected. The combined signal can be demodulated using correlation analysis and a unique iterative cancellation scheme. The accuracy of particle counting and sizing was validated using mixtures of various sized microparticles. Results showed errors of 2.6% and 6.1% in sizing and counting, respectively. We further demonstrated its accuracy for cell analysis using HeLa cells.

Potential Avenues for Exosomal Isolation and Detection Methods to Enhance Small-Cell Lung Cancer Analysis

Around the world, lung cancer has long been the main factor in cancer-related deaths, with small-cell lung cancer (SCLC) being the deadliest form of lung cancer. Cancer cell-derived exosomes and exosomal miRNAs are considered promising biomarkers for diagnosing and prognosis of various diseases, including SCLC. Due to the rapidity of SCLC metastasis, early detection and diagnosis can offer better diagnosis and prognosis and therefore increase the patient's chances of survival. Over the past several years, many methodologies have been developed for analyzing non-SCLC-derived exosomes. However, minimal advances have been made in SCLC-derived exosome analysis methodologies. This Review discusses the epidemiology and prominent biomarkers of SCLC. Followed by a discussion about the effective strategies for isolating and detecting SCLC-derived exosomes and exosomal miRNA, highlighting the critical challenges and limitations of current methodologies. Finally, an overview is provided detailing future perspectives for exosome-based SCLC research.

Current Advances in Technologies for Single Extracellular Vesicle Analysis and Its Clinical Applications in Cancer Diagnosis

Extracellular vesicles (EVs) have been regarded as one of the most potential diagnostic biomarkers for different cancers, due to their unique physiological and pathological functions. However, it is still challenging to precisely analyze the contents and sources of EVs, due to their heterogeneity. Herein, we summarize the advances in technologies for a single EV analysis, which may provide new strategies to study the heterogeneity of EVs, as well as their cargo, more specifically. Furthermore, the applications of a single EV analysis on cancer early diagnosis are also discussed.

Environmental noise reduction for tunable resistive pulse sensing of extracellular vesicles

Extracellular vesicles (EVs) bearing biomolecules from parental cells can represent a novel source of disease biomarkers and are under intensive study for their clinical potential. Tunable resistive pulse sensing (TRPS) quantifies the magnitude of a small ionic resistive pulse current to determine the size, concentration, and zeta potential of EVs. Environmental noise is a common limiting factor that affects the precision of sensing devices. TRPS is particularly vulnerable to environmental noise, including both mechanical and electrical. The upper detection limit of the TRPS relies on the physical size of the elastomeric tunable nanopore. The lower limit relies on the electrical signal-to-noise ratio. Guided by simulation, we designed an external device to suppress environmental noise for TRPS measurement. Both mechanical and electrical environmental noise reductions were observed after using the shield. The study also validated the noise reduction function of the shield by quantifying EVs from different cell origins. Detection of EVs smaller than 200 nm was improved by using the shield; which was reported challenging for conventional quantification methods. The study highlighted a feasible approach to solve environmental noise challenges for TRPS based EV quantification.

Drug-Rich Phases Induced by Amorphous Solid Dispersion: Arbitrary or Intentional Goal in Oral Drug Delivery?

Among many methods to mitigate the solubility limitations of drug compounds, amorphous solid dispersion (ASD) is considered to be one of the most promising strategies to enhance the dissolution and bioavailability of poorly water-soluble drugs. The enhancement of ASD in the oral absorption of drugs has been mainly attributed to the high apparent drug solubility during the dissolution. In the last decade, with the implementations of new knowledge and advanced analytical techniques, a drug-rich transient metastable phase was frequently highlighted within the supersaturation stage of the ASD dissolution. The extended drug absorption and bioavailability enhancement may be attributed to the metastability of such drug-rich phases. In this paper, we have reviewed (i) the possible theory behind the formation and stabilization of such metastable drug-rich phases, with a focus on non-classical nucleation; (ii) the additional benefits of the ASD-induced drug-rich phases for bioavailability enhancements. It is envisaged that a greater understanding of the non-classical nucleation theory and its application on the ASD design might accelerate the drug product development process in the future.

Intriguing Biomedical Applications of Synthetic and Natural Cell-Derived Vesicles: A Comparative Overview

The significant role of a vesicle is well recognized; however, only lately has the advancement in biomedical applications started to uncover their usefulness. Although the concept of vesicles originates from cell biology, it later transferred to chemistry and material science to develop nanoscale artificial vesicles for biomedical applications. Herein, we examine different synthetic and biological vesicles and their applications in the biomedical field in general. As our understanding of biological vesicles increases, more suitable biomimicking synthetic vesicles will be developed. The comparative discussion between synthetic and natural vesicles for biomedical applications is a relevant topic, and we envision this could enable the development of a proper approach to realize the next-generation treatment goals.

Cancer Nanopharmaceuticals: Physicochemical Characterization and In Vitro/In Vivo Applications

Physicochemical, pharmacokinetic, and biopharmaceutical characterization tools play a key role in the assessment of nanopharmaceuticals' potential imaging analysis and for site-specific delivery of anti-cancers to neoplastic cells/tissues. If diagnostic tools and therapeutic approaches are combined in one single nanoparticle, a new platform called nanotheragnostics is generated. Several analytical technologies allow us to characterize nanopharmaceuticals and nanoparticles and their properties so that they can be properly used in cancer therapy. This paper describes the role of multifunctional nanoparticles in cancer diagnosis and treatment, describing how nanotheragnostics can be useful in modern chemotherapy, and finally, the challenges associated with the commercialization of nanoparticles for cancer therapy.

The tox is in the detail: technical fundamentals for designing, performing, and interpreting experiments on toxicity of microplastics and associated substances

Over the last 10 years, there has been a plethora of experimental studies estimating the potential of microplastic particles (MPs) to exert toxic effects in the environment, many specifically focusing on their postulated capacity to enhance the transfer of environmental pollutants into organisms after ingestion. Obviously, there is little to no consensus on appropriate experimental design, which is mainly owing to the novelty, the interdisciplinarity of the subject, and the complexity of parameters involved. This results in fundamental discrepancies regarding the materials applied, the approach for spiking MPs with pollutants, and the exact exposure scenario. Aiming for a non-chemist audience and providing illustrative, representative, and comparative examples, this review first outlines the theoretical essentials of processes involved in sorption. Also, it discusses the implications for designing experimental approaches using MPs and interpreting the results obtained under consideration of their relevance for environmental conditions. It may help to improve the interpretation of studies on MP toxicity already published, while also calling experimenters' attention to various aspects important to consider when designing and performing environmentally relevant experiments with MPs.

Recent advances in single extracellular vesicle detection methods

Extracellular vesicles (EVs) are secreted by a variety of cells. They are known for their pertinent role in intercellular communication, and participation in different pathological processes, making them ideal candidate for utilization as a biomarker for diagnosis and treatment of diseases. In contemporary years, the concept of a well-established liquid biopsy technology, and detection and utilization of EVs as a biomarkers have received unprecedented attention. Many rapid and precise EVs detection methods have been proposed, however, majority of them detect EVs in a bulk. As the prevalent heterogeneity of single extracellular vesicle (SEV) plays an important role in the analysis of disease progression, therefore, to prevent information loss, increased attention has been paid to SEV detection with remarkable successes. Technologies like fluorescence labeling, micro imaging and microfluidic chip were successfully employed for EVs detection at SEV level. This review summarizes the recent advances in SEV detection methods, their potential targets, applications as well as concludes future prospects for developing new SEV detection strategies.

Design of new protein drug delivery system (PDDS) with photoactive compounds as a potential application in the treatment of glioblastoma brain cancer

Glioblastoma multiforme (GBM) is an extremely aggressive malignant brain tumor. Despite advances in treatment modalities, it remains largely incurable. This unfavorable prognosis for GBM is at least partly due to the lack of a successful drug delivery system across the blood-brain barrier (BBB). The delivery of drugs through nanomedicines combined with less invasive alternative therapies represents an important hope for the future of these incurable brain tumors. Whey protein nanocarriers represent promising strategy for targeted drug delivery to tumor cells by enhancing the drug's bioavailability and distribution, and reducing the body's response towards drug resistance. They have been extensively studied to find new alternatives for capacity to encapsulate different drugs and no need for cross-linkers. In this study, we report for the first time the incorporation and administration of Aluminum phthalocyanine chloride (AlClPc)-loaded whey protein drug delivery system (AlClPc-PDDS) for the treatment of glioblastoma brain cancer. This system was designed and optimized (with the use of the spray drying technique) to obtain the required particle size (in the range of 100 to 300 nm), zeta potential and drug loading. Our results suggest that we have developed a drug delivery system from a low-cost raw material and preparation method that is capable of incorporating hydrophobic drugs which, in combination with irradiation, cause photodamage to neoplasic cells, working as an effective adjuvant treatment for malignant glioma.

Probing the conformational switch of I-motif DNA using tunable resistive pulse sensing

I-motif DNA, which can fold and unfold reversibly in various environments, plays a significant role in DNA nanotechnology and biological functions. Thus, it is of fundamental importance to identify the different conformations of i-motif DNA. Here, we demonstrate that distinct structures of i-motif DNA conjugated to polystyrene spheres can be distinguished through tunable resistive pulse sensing technique. When dispersed in acidic buffer, i-motif DNA coating on polystyrene spheres would fold into quadruplex structure and subsequently induce an apparent increase in the translocation duration time upon passing through a nanopore due to the shielding effect of the surface charge of the nanospheres. However, if the DNA strands don't have conformational changes in acidic buffer, little shift can be observed in the translocation duration time of the DNA functionalized polystyrene spheres. A before-and-after assay was also performed to illustrate the fast speed of i-motif DNA folding using this technique. The successful implementation of tunable resistive pulse sensing to monitor the conformational transition of i-motif DNA provides a potential tool to detect the structural changes of DNA and an alternative approach to study the function of DNA structures.

Integrated Method for Purification and Single-Particle Characterization of Lentiviral Vector Systems by Size Exclusion Chromatography and Tunable Resistive Pulse Sensing

Elements derived from lentiviral particles such as viral vectors or virus-like particles are commonly used for biotechnological and biomedical applications, for example in mammalian protein expression, gene delivery or therapy, and vaccine development. Preparations of high purity are necessary in most cases, especially for clinical applications. For purification, a wide range of methods are available, from density gradient centrifugation to affinity chromatography. In this study we have employed size exclusion columns specifically designed for the easy purification of extracellular vesicles including exosomes. In addition to viral marker protein and total protein analysis, a well-established single-particle characterization technology, termed tunable resistive pulse sensing, was employed to analyze fractions of highest particle load and purity and characterize the preparations by size and surface charge/electrophoretic mobility. With this study, we propose an integrated platform combining size exclusion chromatography and tunable resistive pulse sensing for monitoring production and purification of viral particles.

Insights into the Proteome of Gastrointestinal Stromal Tumors-Derived Exosomes Reveals New Potential Diagnostic Biomarkers

Developing tumors continuously release nano-sized vesicles that represent circulating "fingerprints" of the tumor's identity. In gastrointestinal stromal tumor (GIST), we have previously reported that these tumors release "oncosomes" carrying the constitutively activated tyrosine kinase (TK) receptor KIT. Despite the clinical utility of TK inhibitors, such as imatinib mesylate (IM), recurrence and metastasis are clinical problems that urge the need to identify new tumor-derived molecules. To this aim, we performed the first high quality proteomic study of GIST-derived exosomes (GDEs) and identified 1,060 proteins composing the core GDE proteome (cGDEp). The cGDEp was enriched in diagnostic markers (e.g. KIT, CD34, ANO1, PROM1, PRKCQ, and ENG), as well as proteins encoded by genes previously reported expressed in GIST (e.g. DPP4, FHL1, CDH11, and KCTD12). Many of these proteins were validated using cell lines, patient-derived KIT⁺ exosomes, and GIST tissues. We further show that in vitro and in vivo-derived GDE, carry proteins associated with IM response, such as Sprouty homolog 4 (SPRY4), surfeit 4 (SURF4), ALIX, and the cGMP-dependent 3',5'-cyclic phosphodiesterase 2A (PDE2A). Additionally, we report that the total exosome levels and exosome-associated KIT and SPRY4 protein levels have therapeutic values. In fact, molecular characterization of in vivo-derived KIT⁺ exosomes indicate significant sorting of p-KIT^Tyr719, total KIT, and SPRY4 after IM-treatment of metastatic patients as compared with the pre-IM levels. Our data suggest that analysis of circulating exosomes levels and molecular markers of IM response in GIST patients with primary and metastatic disease is suitable to develop liquid based biopsies for the diagnosis, prognosis, and monitoring of response to treatment of these tumors. In summary, these findings provide the first insight into the proteome of GIST-derived oncosomes and offers a unique opportunity to further understand their oncogenic elements which contribute to tumorigenesis and drug resistance. Data are available via ProteomeXchange with identifier PXD007997.

Larger or more? Nanoparticle characterisation methods for recognition of dimers

Larger or more? Our article dissects the problem of understanding the origin of size heterogeneity in polydispersed nanoparticle samples.