Removal Of Dimethyl Sulfoxide Research Articles

Preparation of cryopreserved chimeric antigen receptor T cells for the locoreogional delivery to the neural axis

Background aimsIntracranial (IC) locoregional delivery of chimeric antigen receptor (CAR) T cells presents an attractive delivery method to central nervous system tumors. Although IC delivery is actively being employed in early-phase clinical studies, no thaw/wash methods have been published to remove the neurotoxic cryoprotectant dimethyl sulfoxide (DMSO) from CAR T-cell products before IC administration. Thus, the aim of this study was to develop and validate a simple thaw/wash procedure. MethodsWe developed a thaw/wash procedure that consist of product thaw at 37°C, equilibration for 5 min in 1 volume of preservative-free normal saline (PFNS), dilution with an additional 8 volumes of PFNS, removal of DMSO through a washing step, resuspension in 2.0 mL of PFNS and storage in a syringe at 20–25°C. Final formulated products (FPs) were assessed for quality and safety attributes and stability over 3 h from the completion of the thaw. Stability parameters included CAR T-cell viability, transgene surface expression and cytolytic activity. ResultsThe developed procedure reduced the calculated % of DMSO to less than 0.025%. FP cell viability and recovery (versus pre-cryopreservation) were within acceptable specifications (mean viability: 85.3%, range: 83%–88%; total nucleated cell recovery mean: 76.5%, range: 65.4%–82.5%). Other prespecified quality assurance/quality control parameters including appearance/ integrity, sterility and endotoxin level (≤1.0 EU/mL), were also met by all FPs (n = 3). Three hours’ post thaw/wash stability was confirmed. All products maintained cell viability greater than 70% (mean, 80.0%; range, 79%–81%), with no significant change in transgene expression or cytolytic activity of B7-H3-CAR T cells compared with thawed not diluted/washed control CAR T cells. ConclusionsWe have developed a simple thaw/wash procedure to prepare B7-H3-CAR T cells for their locoregional delivery to the neural axis. While we focus here on CAR T cells, the methods could be readily adapted to other cryopreserved immune effector cell products.

Viability of mononuclear cells in leukocyte concentrates at the stages of their preparation, freezing, and thawing

Aim. To evaluate the viability of mononuclear cells (MNCs) in leukocyte concentrates (LCs) at the stages of their preparation, freezing, and thawing.Materials and methods. The study material included 44 LCs from donors of allogeneic hematopoietic stem cells (HSCs) and 189 autologous LCs from patients with oncohematological disorders. LCs were obtained from donors and patients by leukocytapheresis after mobilization of HSCs. LCs from patients were frozen with dimethyl sulfoxide (DMSO) used as a cryoprotectant at a final concentration of 5% and stored in liquid nitrogen. LCs were thawed before transplantation. A total of 161 LCs were immediately transfused to the recipient after thawing, and 28 LCs were washed from DMSO before transfusion. Flow cytofluorometry was used to determine the percentage of MNC populations that excluded 7-aminoactinomycin D (7-AAD).Results. The viability of peripheral blood MNCs in donors and patients was close to 100%. It was found that leukocytapheresis and cryopreservation with DMSO did not affect the viability of MNCs. The freezing of LCs with DMSO, storage in liquid nitrogen, and thawing resulted in a significant decrease in the content of viable MNCs (p = 0.0025), while no effect of LC storage duration on the viability of MNCs was revealed. Following DMSO removal from LCs, significantly more HSCs remained in a viable state than without washing (94.4 [94.5; 95.2] % vs. 86.7 [67.6; 92.9] %, (p = 0.0051); for other MNC populations, except monocytes, the differences in the viability index were also statistically significant.Conclusion. The viability of MNCs in LCs is recommended to be used as an independent characteristic of the transplant quality. In obtaining LCs and mixing them with the cryoprotectant DMSO, the viability of MNCs does not decrease, while in thawed LCs, it decreases significantly. Thawing of LCs with removal of DMSO allows to achieve the best viability of HSCs and most MNC populations.

Effect of Solvent and Monomer Ratio on the Properties of Polyphenylene Sulphone.

For the first time, the effect of the solvent and monomer ratio on molecular weight, chemical structure, and mechanical, thermal, and rheological characteristics of polyphenylene sulfone has been studied. When dimethylsulfoxide (DMSO) is used as a solvent, cross-linking occurs during the processing of the polymer, which is accompanied by an increase in melt viscosity. This fact sets a pressing need for the complete removal of DMSO from the polymer. The best solvent used for the production of PPSU is N,N-dimethylacetamide. This study of the molecular weight characteristics of polymers by gel permeation chromatography showed the stability of the polymers practically does not change with a decrease in molecular weight. The synthesized polymers correspond in tensile modulus to the commercial analog Ultrason-P, while exceeding it in terms of tensile strength and relative elongation at break. Thus, the developed polymers are promising for spinning hollow fiber membranes with a thin selective layer.

Application of Photo-Fenton, Electro-Fenton, and Photo-Electro-Fenton processes for the treatment of DMSO and DMAC wastewaters

Biological treatment, due to the formation of hazardous chemicals to remove organic compounds such as dimethyl sulfoxide (DMSO) and N, N-dimethylacetamide (DMAC), has limited potential. Advanced oxidation processes (AOPs) are regarded as a viable alternative for treating molecules containing carbon-hydrogen bonds that cannot be broken down by traditional physico-chemical methods. In this investigation, various AOPs such as Photo-Fenton, Electro-Fenton, and Photo-Electro-Fenton processes were studied to treat wastewaters containing DMSO and DMAC. The effects of the operating parameters, including various initial concentrations of DMSO and DMAC, initial pH, reaction time, different concentrations of Fenton’s reagent, power of UV lamp, different concentrations of electrolytes, the distance between electrodes and current intensity, were investigated. The findings of the experiments revealed that a pH of 3 and a reaction time of 120 min were optimal. At 2000 mg L−1 of DMSO, maximum degradation and the final concentration of TOC were 98.64 % and 256.8 mg L−1, respectively, by the Electro-Fenton process under the optimal conditions. The Electro-Fenton process was successful in determining the maximum degradation of DMAC (96.31 %) and the final TOC concentration (10.03 mg L−1) at 250 mg L−1 of DMAC under optimal conditions. Finally, it can be concluded that the Electro-Fenton process was the best process for the efficient removal of DMSO and DMAC. The second step of the kinetic model follows a pseudo-first-order reaction for 250 and 500 mg L−1 of pollutants and obeyed a pseudo-second-order kinetic model for concentrations of 1000, 2000 mg L−1.

A comparative study on the removal of dimethyl sulfoxide from water using microbubbles and millibubbles of ozone

Ozone-based microbubble-aided technology has been gaining popularity as a new potential alternative method for the oxidation of organic pollutants present in water/wastewater. In this work, the potential of the ozone microbubbles (OMBs) for the oxidation of dimethyl sulfoxide (DMSO) was investigated, and the results were compared with those of the conventional ozone millibubbles (OMLBs). Keeping constant other operational parameters, the OMLBs needed a longer time for complete removal of DMSO, and hence a higher consumption of ozone took place. Therefore, a higher stoichiometric ratios of ozone consumed to the DMSO removed was obtained for the OMLBs. Higher ozone utilization efficiencies were observed for the OMBs (i.e., 65–79 %) than the OMLBs (i.e., 21–48 %). Coupling of H2O2 with the ozonation systems improved the oxidation of DMSO by enhancing the formation of ·OH. Conversely, a large dosage of H2O2 had a negative effect. The degradation of DMSO to methane sulfonic acid (MSA) was achieved via two paths (i.e., direct conversion to MSA by the reaction with ·OH, and a two-stage conversion via the formation of DMSO2 by molecular ozone, followed by further oxidation of DMSO2 to MSA by the ·OH). In terms of the TOC removal efficiency, the effectiveness was in the following order: OMLBs < OMLBs/H2O2 < OMBs < OMBs/H2O2. Oxidation of DMSO by ozone followed an overall second-order kinetics for the OMBs, and first-order kinetics for the OMLB system. Higher enhancement factor and volumetric mass transfer coefficient were obtained for the OMBs as compared to OMLBs.

Cryopreservation of the common carotid artery of the rabbit: Optimization of dimethyl sulfoxide concentration and cooling rate

This paper describes the continuation of studies that demonstrated the suitability of CP-Tes solution as a medium for the introduction and removal of dimethyl sulfoxide in rabbit common carotid arteries and established the kinetics of cryoprotectant permeation in that tissue. In this paper we report the tolerance of rabbit common carotid artery to dimethyl sulfoxide, in concentrations up to 30% (w/w), using a technique of exposure that was designed to control osmotic stress. The maximum concentration achieved without damage was 15% (w/w). Vessels were then equilibrated with 15% dimethyl sulfoxide and cooled to −80 °C at 0.22, 0.69, 2.15, or 9.63 °C/min: they were then transferred to the gas phase of a liquid nitrogen refrigerator {temperature below −160 °C) for storage. Thawing was carried out in a 37 °C water bath. The optimum rate of cooling for these conditions was found to be 0.69 °C/min. The maximal recovery of contractile force in response to 10−6 M norepinephrine was 30–40%; relaxation to acetylcholine (an endothelium-mediated function) was 80% of control, and an estimated 71% of endothelial cells survived with minimal ultrastructural change.

Dimethylsulfoxide Inhibits Oligodendrocyte Fate Choice of Adult Neural Stem and Progenitor Cells.

Several clinical trials address demyelinating diseases via transplantation of mesenchymal stromal cells (MSCs). Published reports detail that administration of MSCs in patients may provide a beneficial immunomodulation, and that factors secreted by MSCs are potent inducers of oligodendrogenesis. Dimethylsulfoxide (DMSO) is widely used in life science and medicine as solvent, vehicle or cryoprotectant for cells used in transplantation. Importantly, most transplantation protocols do not include the removal of DMSO before injecting the cell suspension into patients. This indifferent application of DMSO is coming under increasing scrutiny following reports investigating its potential toxic side-effects. While the impact of DMSO on the central nervous system (CNS) has been partially studied, its effect on oligodendrocytes and oligodendrogenesis has not been addressed yet. Consequently, we evaluated the influence of DMSO on oligodendrogenesis, and on the pro-oligodendrogenic effect of MSCs’ secreted factors, using adult rat neural stem and progenitor cells (NSPCs). Here, we demonstrate that a concentration of 1% DMSO robustly suppressed oligodendrogenesis and drove the fate of differentiating NSPCs toward astrogenesis. Furthermore, the pro-oligodendrogenic effect of MSC-conditioned medium (MSCCM) was also nearly completely abolished by the presence of 1% DMSO. In this condition, inhibition of the Erk1/2 signal transduction pathway and high levels of Id2 expression, a specific inhibitor of oligodendrogenic differentiation, were detected. Furthermore, inflammatory demyelinating diseases may even potentiate the impact of DMSO on oligodendrogenesis. Our results demonstrate the imperative of considering the strong anti-oligodendrogenic activity of DMSO when designing future clinical trial protocols.

High performance perovskite solar cells fabricated from porous PbI2-xBrx prepared with mixture solvent pore generation treatment

Power conversion efficiencies of perovskite solar cells depend heavily on the uniformity, coverage, grain size, and thickness of the perovskite layer. In this study, hybrid perovskite CH3NH3PbI3-xBrx thin films were fabricated from porous PbI2-xBrx layers prepared with a mixture solvent pore generation treatment process. The mixture solvent is composed of two anti-solvents of PbI2-xBrx to promote its crystallization, one with a low boiling point to accelerate the evaporative removal of the solvents of PbI2-xBrx, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the other with a high boiling point to modulate the evaporative removal of DMF and DMSO to achieve a suitably configured porous structure for the PbI2-xBrx layer. With this fast pore generation treatment, uniform porous PbI2-xBrx layers were obtained within minutes, far more efficient than previously reported pore generation processes. The uniform porous PbI2-xBrx layer enabled formation of hybrid perovskite CH3NH3PbI3-xBrx thin films of low PbI2-xBrx residue, good crystallinity, low defect concentrations, and long charge carrier life times. The champion cell, assembled from the optimal hybrid perovskite thin films fabricated from optimized pore generation treatments, exhibited significantly superior power conversion performances of 19.26 mA/cm2 for the short circuit current density, 1.01 V for the open circuit voltage, 0.68 for the fill factor, and 13.16% for the power conversion efficiency, as compared to the average power conversion efficiency of 10.03% for non-porous PbI2-xBrx layer based cells.

Dual stimuli-responsive rotaxane-branched dendrimers with reversible dimension modulation

With the aim of mimicking biological machines, in which the delicate arrangement of nanomechanical units lead to the output of specific functions upon the external stimulus, the construction of dual stimuli-responsive rotaxane-branched dendrimers was realized in this study. Starting from a switchable organometallic [2]rotaxane precursor, the employment of a controllable divergent approach allowed for the successful synthesis of a family of rotaxane-branched dendrimers up to the third generation with 21 switchable rotaxane moieties located on each branch. More importantly, upon the addition and removal of dimethylsulfoxide (DMSO) molecule or acetate anion as the external stimulus, the amplified responsiveness of the switchable rotaxane units endowed the resultant rotaxane-branched dendrimers the solvent- or anion-controlled molecular motions, thus leading to the dimension modulation. Therefore, we successfully constructed a family of rotaxane-branched dendrimers with dual stimuli-responsiveness that will be a privileged platform for the construction of dynamic supramolecular materials.

Poly(glyoxylates): a new class of depolymerizable materials with amplified response to stimuli and applications in drug delivery

Event Abstract Back to Event Poly(glyoxylates): a new class of depolymerizable materials with amplified response to stimuli and applications in drug delivery Bo Fan1 and Elizabeth Gillies1, 2 1 The University of Western Ontario, Department of Chemical and Biochemical Engineering, Canada 2 The University of Western Ontario, Department of Chemistry, Canada Introduction: In recent years, there has been significant interest in stimuli-responsive materials[1],[2]. While successful in the lab, a challenge in their application is that numerous stimuli-mediated events are required to impart changes in properties. Self-immolative polymers (SIPs) were developed to address this limitation[3],[4]. Upon cleavage of a single stimulus-responsive end-cap, an SIP undergoes complete end-to-end depolymerization. Several SIP backbones including polycarbamates[5],[6], and poly(o-phthalaldehyde)s[7] have been developed. However, their application has been hindered by: 1) expensive, multistep monomer syntheses; 2) depolymerization to toxic species such as quinone methides or o-phthalaldehyde[8]. Described here is poly(ethyl glyoxylate) (PEtG) as a linear SIP and its application in stimuli-responsive micelles for drug delivery. PEtG can be synthesized from the commercially available monomer ethyl glyoxylate (EtG). Depolymerization produces glyoxylic acid hydrate[9], a metabolic intermediate in the glyoxylic acid cycle which has been shown to be non-toxic (Fig. 1b)[10]. Methods: EtG was distilled twice over P2O5, dissolved in CH2Cl2, and then polymerized for 1 h at -20 °C in the presence of NEt3 (Fig. 2)[11]. To end-cap the polymer, 1 was added. The solution was allowed to reach ambient temperature over 24 h then heated at 40 °C for 16 h. The polymer 2 was precipitated in methanol. A similar strategy could be used to also prepare PEtG with end-caps responsive to stimuli such as H2O2 or thiols by varying the structure of end-cap 1. Block copolymer 3 was formed by coupling with an azide-terminated poly(ethylene oxide) (PEO, 2 kg/mol) in N,N-dimethylformamide (DMF) in the presence of CuSO4 and sodium ascorbate. Self-assembly was performed by the addition of a dimethylsulfoxide (DMSO) solution of block copolymer into water followed by the removal of DMSO by dialysis. Doxorubicin loading was accomplished using a dialysis procedure[12]. Micelle degradation was triggered by irradiation with UV light (wavelength: 300-350 nm, 23 mWcm-2), while controls were kept in the dark. Results and Discussion: Polymerization of EtG afforded polymer 2 with a number average molar mass (Mn) of 42 kg/mol and a dispersity (Đ) of 2.0 based on size exclusion chromatography (SEC) in tetrahydrofuran relative to polystyrene standards. End-cap 1 is cleavable with UV light and also has an alkyne for conjugation of another polymer. Coupling of PEO was confirmed by a combination of SEC and NMR spectroscopy. Self-assembly of the resulting amphiphilic copolymer 3 afforded micelles with diameters of ~50 nm as measured by dynamic light scattering and transmission electron microscopy (Fig. 3a). Irradiation with UV light for 10 min resulted in rapid depolymerization of the micelles as measured by NMR spectroscopy. In contrast a non-irradiated control was stable for 24 h. To demonstrate the application of these micelles for triggered anti-cancer drug delivery, they were loaded with doxorubicin (Dox). Irradiation resulted in release of 75% of Dox over 50 h, in comparison with a control that was not irradiated and released only 20% of the drug over this time (Fig. 3b). Conclusions: PEtG was synthesized and capped with a moiety imparting responsiveness to UV light and enabling conjugation of PEO to afford an amphiphilic SIP. The copolymer assembled into micelles and these micelles rapidly depolymerized in response to UV light. The anti-cancer drug Dox was loaded into the micelles and they afforded selected release of Dox upon irradiation. These results, combined with the depolymerization of PEtG to non-toxic glyoxylic acid suggest the promise of these materials for drug delivery applications. It is also possible to easily tune the responsiveness to different stimuli by changing the end-cap. We thank the Natural Sciences and Engineering Research Council of Canada as well as Western University for funding this work.

Cryoprotective Effect of Disaccharides on Cord Blood Stem Cells with Minimal Use of DMSO.

Umbilical cord blood (UCB) is an extremely attractive source of stem cells for the treatment of various benign and malignant hematological and non-hematological disorders. To facilitate the preservation of these stem cells, 10% dimethylsulfoxide (DMSO) is widely used as cryoprotectant in cord blood banks. But it is found to be toxic at this concentration with the result of serious side effects in recipients after infusion of DMSO-cryopreserved cells. Evaluation of viability and functionality of cryopreserved hematopoietic stem cells is needed with either inclusion of nontoxic additives alone or with reduced DMSO concentration. We assessed the post thawing viability of UCB stem cells in the freezing medium containing disaccharides (sucrose or trehalose) alone and in combination with reduced amount i.e. 2% DMSO by trypan blue staining. The functionally active progenitor cells content of the optimized media was then evaluated and compared with 5% DMSO by a colony forming unit assay using methylcellulose based media. The freezing solution containing 0.2M trehalose with 2% DMSO came out to be superior in the evaluation of viability and generation of hematopoietic colonies of erythroid and myeloid lineage than 5% DMSO alone. While the percentage of viability was lower than 2% DMSO, as observed in the medium containing 0.2M trehalose or sucrose alone, with poor outcome of generation of myeloid lineage based colonies. Our study results suggest that trehalose (0.2M) with the inclusion of reduced concentration of DMSO(2%) can better replace 5%DMSO rather than complete removal of DMSO from the freezing medium.

The hemostatic activity of cryopreserved platelets is mediated by phosphatidylserine‐expressing platelets and platelet microparticles

Cryopreservation of platelets (PLTs) at -80°C with dimethyl sulfoxide (DMSO) can extend the shelf life from 5 days to 2 years. Cryopreserved PLTs are reported to have a greater in vivo hemostatic effect than liquid-stored PLTs. As such, the aim of this study was to understand the mechanisms responsible for the hemostatic potential of cryopreserved PLTs and the contribution of the reconstitution solution to this activity. DMSO (5% final concentration) was added to buffy coat-derived PLTs, followed by prefreeze removal of DMSO and storage at -80°C. Cryopreserved PLTs (n=8 per group) were thawed at 37°C, reconstituted with either 1 unit of thawed frozen plasma or PLT additive solution (PAS-G). In vitro assays were performed before freezing and after thawing to assess the hemostatic activity of PLTs. Cryopreserved PLTs expressed high levels of phosphatidylserine and contained significantly more phosphatidylserine-positive PLT microparticles than liquid-stored PLTs. This was accompanied by a significant decrease in the time to clot formation and clot strength, as measured by thromboelastography. The supernatant from cryopreserved PLTs was sufficient to reduce the phosphatidylserine-dependent clotting time and increase the thrombin generation potential. Overall, plasma-reconstituted cryopreserved PLTs were more procoagulant than those reconstituted in PAS-G. PLT cryopreservation results in the generation of phosphatidylserine-expressing PLT microparticles which contribute to the hemostatic activity. Understanding the hemostatic activity of these components may assist in extending the use of these specialized components beyond military applications.

Hematopoietic SCT with cryopreserved grafts: adverse reactions after transplantation and cryoprotectant removal before infusion

Transplantation of hematopoietic stem cells (HSCs) has been successfully developed as a part of treatment protocols for a large number of clinical indications, and cryopreservation of both autologous and allogeneic sources of HSC grafts is increasingly being used to facilitate logistical challenges in coordinating the collection, processing, preparation, quality control testing and release of the final HSC product with delivery to the patient. Direct infusion of cryopreserved cell products into patients has been associated with the development of adverse reactions, ranging from relatively mild symptoms to much more serious, life-threatening complications, including allergic/gastrointestinal/cardiovascular/neurological complications, renal/hepatic dysfunctions, and so on. In many cases, the cryoprotective agent (CPA) used-which is typically dimethyl sulfoxide (DMSO)-is believed to be the main causal agent of these adverse reactions and thus many studies recommend depletion of DMSO before cell infusion. In this paper, we will briefly review the history of HSC cryopreservation, the side effects reported after transplantation, along with advances in strategies for reducing the adverse reactions, including methods and devices for removal of DMSO. Strategies to minimize adverse effects include medication before and after transplantation, optimizing the infusion procedure, reducing the DMSO concentration or using alternative CPAs for cryopreservation and removing DMSO before infusion. For DMSO removal, besides the traditional and widely applied method of centrifugation, new approaches have been explored in the past decade, such as filtration by spinning membrane, stepwise dilution-centrifugation using rotating syringe, diffusion-based DMSO extraction in microfluidic channels, dialysis and dilution-filtration through hollow-fiber dialyzers and some instruments (CytoMate, Sepax S-100, Cobe 2991, microfluidic channels, dilution-filtration system, etc.) as well. However, challenges still remain: development of the optimal (fast, safe, simple, automated, controllable, effective and low cost) methods and devices for CPA removal with minimum cell loss and damage remains an unfilled need.

Transduction of pressure signal to electrical signal upon sudden increase in turgor pressure in Chara corallina

By taking advantage of large cell size of Chara corallina, we analyzed the membrane depolarization induced by decreased turgor pressure (Shimmen in J Plant Res 124:639-644, 2011). In the present study, the response to increased turgor pressure was analyzed. When internodes were incubated in media containing 200 mM dimethyl sulfoxide, their intracellular osmolality gradually increased and reached a steady level after about 3 h. Upon removal of dimethyl sulfoxide, turgor pressure quickly increased. In response to the increase in turgor pressure, the internodes generated a transient membrane depolarization at its nodal end. The refractory period was very long and it took about 2 h for full recovery after the depolarizing response. Involvement of protein synthesis in recovery from refractoriness was suggested, based on experiments using inhibitors.

Cryopreservation of platelets using trehalose: The role of membrane phase behavior during freezing

In blood banks, platelets are stored at 20-24 °C, which limits the maximum time they can be stored. Platelets are chilling sensitive, and they activate when stored at temperatures below 20 °C. Cryopreservation could serve as an alternative method for long term storage of platelet concentrates. Recovery rates using dimethyl sulfoxide (DMSO) as cryoprotective agent, however, are low, and removal of DMSO is required before transfusion. In this study, we have explored the use of trehalose for cryopreservation of human platelets while using different cooling rates. Recovery of membrane intact cells and the percentage of nonactivated platelets were used as a measure for survival. In all cases, survival was optimal at intermediate cooling rates of 20 °C min(-1). Cryopreservation using DMSO resulted in high percentages of activated platelets; namely 54% of the recovered 94%. When using trehalose, 98% of the platelets had intact membranes after freezing and thawing, whereas 76% were not activated. Using Fourier transform infrared spectroscopy, subzero membrane phase behavior of platelets has been studied in the presence of trehalose and DMSO. Furthermore, membrane hydraulic permeability parameters were derived from these data to predict the cell volume response during cooling. Both trehalose and DMSO decrease the activation energy for subzero water transport across cellular membranes. Platelets display a distinct lyotropic membrane phase transition during freezing, irrespective of the presence of cryoprotective agents. We suggest that concomitant uptake of trehalose during freezing could explain the increased survival of platelets cryopreserved with trehalose.

Effect of PEDOT:PSS–molecule interface on the charge transport characteristics of the large-area molecular electronic junctions

We have studied the effect of the PEDOT:PSS–molecule contact on the electrical characteristics of molecular junctions consisting of N-alkanedithiol and naphthalenethiol molecules. In this study, we experimentally investigated the properties of PEDOT:PSS-interlayer molecular junctions as they depended on the two kinds of PEDOT:PSS films (the pure PEDOT:PSS film and the dimethyl sulfoxide (DMSO)-modified PEDOT:PSS film) and their thermal annealing treatment. We observed that the electrical properties of these molecular junctions are influenced by the morphology and conductivity of the PEDOT:PSS films and by the thermal treatment. In particular, the resistance of the PEDOT:PSS-interlayer molecular junctions depended on the kind of PEDOT:PSS film and the temperature, within the range of elevated temperatures (higher than room temperature) tested. These experimental results are explained by the change of the interfacial properties of the PEDOT:PSS–molecule contact, which are influenced by the morphology change of the PEDOT:PSS film and the removal of residual DMSO or water from the interface.

Effects of freezing profile parameters on the survival of cryopreserved rat embryonic neural cells

The ability to successfully cryopreserve neural cells would represent an important advance with benefits to neural tissue engineering, neural transplantation, and neuroscience research. We have examined key factors responsible for damage to rat embryonic neural cells during cryopreservation using a two-step temperature profile, with an emphasis on the effects of cooling rate and plunge temperature. Our results indicate that the initial addition of 8% dimethyl sulfoxide (DMSO) and seeding of extracellular ice do not significantly decrease viable cell yield. However, subsequent freezing resulted in significant cell losses for all profile parameter combinations examined. A maximum post-thaw survival of 56% (compared to unfrozen controls) was observed after cooling at 2°C/min to −80°C followed by direct immersion in liquid nitrogen. Single-step removal of DMSO after thawing was associated with an additional 40–70% loss of viable cells, and the number of viable cells was further reduced by approximately 70% after 2 days of cell culture (resulting in a net viable cell yield of 9.6±0.4%). Nonetheless, the cryopreserved neurons that did survive displayed a normal morphology, including formation of neurites. Trends in neuronal viability conformed with predictions of existing theoretical models of cell freezing, with reduced survival for rapid cooling rates or high plunge temperatures (attributable to intracellular ice formation), and decreasing viability with increasing profile duration (consistent with the known effects of cell dehydration at suboptimal cooling rates). These observations suggest that neural cells are good candidates for further refinement of freezing profile design using a physics-based approach to parameter optimization.

Use of cryoprotectant-depleted allogeneic peripheral blood stem cells for transplantation

Transplantation with cryopreserved allogeneic peripheral blood stem cells (PBSCs) from related donors is widely conducted in Japan. To freeze PBSCs, a solution containing dimethyl sulfoxide (DMSO), which can have various adverse effects, is added. DMSO-depleted allogeneic PBSCs were transplanted into 21 patients. The cryoprotectant was manually removed from thawed PBSCs and the cells were mixed with a solution containing citrate dextrose as an anticoagulant and RPMI-1640 medium. DMSO-depleted PBSCs were immediately infused into patients subjected to conditioning. Infusion-related adverse effects were only observed in three patients. The median neutrophil recovery (⩾0·5×109/l) and platelet recovery (⩾20×109/l) were 13·0 and 14·0 days, respectively. Only one patient with mixed-lineage leukemia in non-complete remission did not show engraftment, likely due to a second transplantation and a two-antigen disparity in human leukocyte antigen system A. The results suggest the removal of DMSO from thawed PBSCs to be safe and useful for transplantation.

A high throughput dried DMSO Log D lipophilicity measurement based on 96-well shake-flask and atmospheric pressure photoionization mass spectrometry detection

A rapid throughput octanol–water lipophilicity measurement based on 96-well shake-flask and LC/UV/APPI/MS is described. The method utilizes central liquid storage where compounds are stored as 10 mM solutions in dimethyl sulfoxide (DMSO). The DMSO is subsequently removed to generate solid like material used for Log D measurement. The removal of DMSO minimizes the concern for potential DMSO cosolvent effect on the measured value. Sample preparation is automated using a liquid handling workstation with 96-well pipetter. Both octanol and buffer phases are quantified using state of the art ultra-high pressure HPLC coupled with a superficially diffused core reversed-phase column and an atmospheric pressure photo ionization mass spectrometer. The throughput of the method is two days for a batch of 96 compounds. The method has been validated using 72 literature compounds with diverse ionization and Log D values ranging from −2 to +6. The observed coefficient of determination r 2 is 0.9973.

Removal of dimethylsulfoxide from wastewater using mild oxidation with H 2O 2 over Ti-based catalysts

The mild catalytic oxidation of dimethylsulfoxide (DMSO) into biodegradable dimethylsulfone is proposed as an efficient pretreatment of wastewaters subjected to biological treatment processes. A SiO 2–TiO 2 mesoporous xerogel prepared by a non-hydrolytic route, as well as titanium silicalite TS-1 showed very good activity and stability in the catalytic oxidation of DMSO with H 2O 2 in dilute aqueous solution, at room temperature.