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2024 – Janus microparticles-based targeted and spatially-controlled piezoelectric neural stimulation via low-intensity focused ultrasound
Buffer solutions Publication in Nature communications (2024) Authors: Han M., Yildiz E., Bozuyuk U., Aydin A., Yu Y., Bhargava A., Karaz S., Sitti M.

Electrical stimulation is a fundamental tool in studying neural circuits, treating neurological diseases, and advancing regenerative medicine. Injectable, free-standing piezoelectric particle systems have emerged as non-genetic and wireless alternatives for electrode-based tethered stimulation systems. However, achieving cell-specific and high-frequency piezoelectric neural stimulation remains challenging due to high-intensity thresholds, non-specific diffusion, and internalization of particles. Here, we develop cell-sized 20 μm-diameter silica-based piezoelectric magnetic Janus microparticles (PEMPs), enabling clinically-relevant high-frequency neural stimulation of primary neurons under low-intensity focused ultrasound. Owing to its functionally anisotropic design, half of the PEMP acts as a piezoelectric electrode via conjugated barium titanate nanoparticles to induce electrical stimulation, while the nickel-gold nanofilm-coated magnetic half provides spatial and orientational control on neural stimulation via external uniform rotating magnetic fields. Furthermore, surface functionalization with targeting antibodies enables cell-specific binding/targeting and stimulation of dopaminergic neurons. Taking advantage of such functionalities, the PEMP design offers unique features towards wireless neural stimulation for minimally invasive treatment of neurological diseases.

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2023 – A simple quantitative model of neuromodulation, Part I: Ion flow through neural ion channels
Buffer Solutions Publication in Journal of the Mechanics and Physics of Solids (2023) Authors: Werneck L., Han M., Yildiz E., Keip M., Sitti M., Ortiz M.

We develop a simple model of ionic current through neuronal membranes as a function of membrane potential and extracellular ion concentration. The model combines a simplified Poisson–Nernst–Planck (PNP) model of ion transport through individual ion channels with channel activation functions calibrated from ad hoc in-house experimental data. The simplified PNP model is validated against bacterial gramicidin A ion channel data. The calibrated model accounts for the transport of calcium, sodium, potassium, and chloride and exhibits remarkable agreement with the experimentally measured current–voltage curves for the differentiated human neural cells. All relevant data and code related to the ion flow models are available at Werneck et al. (2023)

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2023 – Recombinant cellular model system for human muscle‑type nicotinic acetylcholine receptor α1(2)β1δε
Patchliner and Buffer Solution Publication in Cell Stress and Chaperones (2023) Authors: Brockmöller S., Seeger T., Worek F., Rothmiller S.

The human muscle-type nicotinic acetylcholine receptor α12β1δε (nAChR) is a complex transmembrane receptor needed for drug screening for disorders like congenital myasthenic syndromes and multiple pterygium syndrome. Until today, most models are still using the nAChR from Torpedo californica electric ray. A simple reproducible cellular system expressing functional human muscle-type nAChR is still missing. This study addressed this issue and further tested the hypothesis that different chaperones, both biological and chemical, and posttranslational modification supporting substances as well as hypothermic incubation are able to increase the nAChR yield. Therefore, Gibson cloning was used to generate transfer plasmids carrying the sequence of nAChR or chosen biological chaperones to support the nAChR folding in the cellular host. Viral transduction was used for stable integration of these transgenes in Chinese hamster ovary cells (CHO). Proteins were detected with Western blot, in-cell and on-cell Western, and the function of the receptor with voltage clamp analysis. We show that the internalization of nAChR into plasma membranes was sufficient for detection and function. Additional transgenic overexpression of biological chaperones did result in a reduced nAChR expression. Chemical chaperones, posttranslational modification supporting substances, and hypothermic conditions are well-suited supporting applications to increase the protein levels of different subunits. This study presents a stable and functional cell line that expresses human muscle-type nAChR and yields can be further increased using the chemical chaperone nicotine without affecting cell viability. The simplified access to this model system should enable numerous applications beyond drug development.

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2023 – Voltage-gated sodium channels, potential targets of Tripterygium wilfordii Hook. f. to exert activity and produce toxicity
Port-a-Patch Publication in J. Ethnopharmacol. (2023). Authors: Xu Y., Li W., Wen R., Sun J., Liu X., Zhao S., Zhang J., Liu Y., Zhao M.

Ethnopharmacology relevance
Tripterygium wilfordii Hook. f. has been widely used in clinical practice due to its good anti-inflammatory and analgesic activities. However, its application is limited by potential toxicity and side effects.

Aim of the study
The study aimed to identify the mechanisms responsible for the pharmacological activity and cardiotoxicity of the main monomers of Tripterygium wilfordii.

Materials and methods
Database analysis predicted that ion channels may be potential targets of Tripterygium wilfordii. The regulatory effects of monomers (triptolide, celastrol, demethylzeylasteral, and wilforgine) on protein Nav1.5 and Nav1.7 were predicted and detected by Autodock and patch clamping. Then, we used the formalin-induced pain model and evaluated heart rate and myocardial zymograms to investigate the analgesic activity and cardiotoxicity of each monomer in vivo.

Results
All four monomers were able to bind to Nav1.7 and Nav1.5 with different binding energies and subsequently inhibited the peak currents of both Nav1.7 and Nav1.5. The monomers all exhibited analgesic effects on formalin-induced pain; therefore, we hypothesized that Nav1.7 is one of the key analgesic targets. Demethylzeylasteral reduced heart rate and increased the level of creatine kinase-MB, thus suggesting a potential cardiac risk; data suggested that the inhibitory effect on Nav1.5 might be an important factor underlying its cardiotoxicity.

Conclusion
Our findings provide an important theoretical basis for the further screening of active monomers with higher levels of activity and lower levels of toxicity.

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2022 – Prediction and verification of potential lead analgesic and antiarrhythmic components in Corydalis yanhusuo W. T. Wang based on voltage-gated sodium channel proteins
Port-a-Patch and Buffer Solution Publication in International Journal of Biological Macromolecules (2022) Authors: Sun J., Liu X., Zhao S., Zhang S., Yang L., Zhang J., Zhao M., Xu Y.

Corydalis yanhusuo W. T. Wang, a traditional Chinese herbal medicine, has been used as an analgesic for thousands of years and it also promotes blood circulation. In this study, 33 Corydalis yanhusuo alkaloid active components were acquired from Traditional Chinese Medicine Database and Analysis Platform (TCMSP). A total of 543 pain-related targets, 1774 arrhythmia targets, and 642 potential targets of these active components were obtained using Swiss Target Prediction, GeneCards, Open Target Platform, and Therapeutic Target Database. Fifty intersecting targets were visualized through a Venn diagram, KEGG and GO pathway enrichment analysis. The analysis proposed that sodium ion channels are likely potential targets of Corydalis yanhusuo active components as analgesia and anti-arrhythmia agents. Molecular docking showed that the 33 components could bind to NaV1.7 and NaV1.5 (two subtypes of ion channel proteins) with different binding energies. In a patch clamp study, dihydrosanguinarine and dihydrochelerythrine, two monomers with the strongest binding effects, could inhibit the peak currents and promote both activation and inactivation phases of NaV1.5. Meanwhile, dihydrosanguinarine and dihydrochelerythrine could also inhibit peak currents and promote the activation phase of NaV1.7. Therefore, the findings from this study provide valuable information for future uses of traditional Chinese medicines to treat pain and cardiovascular disease.

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2021 – Active components of Bupleurum chinense and Angelica biserrata showed analgesic effects in formalin induced pain by acting on NaV1.7
Port-a-Patch and Buffer Solution Publication in Journal of Ethnopharmacology (2021) Authors: Xu Y., Yu Y., Wang Q., Li W., Zhang S., Liao X., Liu Y., Su Y., Zhao M., Zhang J.

Ethnopharmacology relevance - Pain is an unpleasant sensory and emotional experience, often accompanied by the occurrence of a variety of diseases. More than 800 kinds of traditional Chinese medicines (TCM) has now been reported for pain relief and several monomers have been developed into novel analgesic drugs. Bupleurum chinense and Angelica biserrata were representatives of the TCM that are currently available for the treatment of pain.

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2021 – Ultrasound mediated cellular deflection results in cellular depolarization
Buffer Solution Publication in Advanced Science (2021)  Authors: Vasan A., Orosco J., Magara U., Duque M., Weiss C., Tufail Y., Chalasani S.H., Friend J.Advanced Science (2021)

Existing methods to stimulate neural activity include electrical optical and chemical techniques. They have enabled the development of novel therapies that are used in clinical settings, in addition to helping understand aspects of neural function and disease mechanisms. Despite their beneficial impact, these approaches are fundamentally limited. Electrical stimulation is invasive, requiring direct contact with the target of interest. Inserting electrodes into the brain may lead to inflammation, bleeding, cell death, and local cytokine concentration increases in microglia that precipitate astrocyte formation around the electrodes that, in turn, reduce long-term effectiveness. In addition, it may have non-specific effects depending on the electric field generated by the electrodes and the stimulation parameters used. Transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (tMS) are new and non-invasive, yet they have poor spatial resolution on the order of 1 cm. Furthermore, approaches combining genetic tools with light or small molecules achieve cellular specificity. Optogenetics, which involves the use of light and genetically encoded membrane proteins, has enabled elucidation of cellular circuits in animal models. However, it remains an invasive technique and applications are limited by the depth of penetration of light in tissue. In contrast, chemogenetics, using small molecule sensitive designer receptors, is limited by poor temporal resolution and is unfortunately impractical for many neural applications that require millisecond response times

Product Sheet PDF
Buffer Solutions – Product Sheet

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