Residual Dimethyl Sulfoxide Research Articles

Enhancing lead-free photovoltaic performance: Minimizing buried surface voids in tin perovskite films through weakly polar solvent pre-treatment strategy

Buried interfacial voids have always been a notorious phenomenon observed in the fabrication of lead perovskite films. The existence of interfacial voids at the buried interface will capture the carrier, suppress carrier transport efficiencies, and affect the stability of photovoltaic devices. However, the impact of these buried interfacial voids on tin perovskites, a promising avenue for advancing lead-free photovoltaics, has been largely overlooked. Here, we utilize an innovative weakly polar solvent pre-treatment strategy (WPSPS) to mitigate buried interfacial voids of tin perovskites. Our investigation reveals the presence of numerous voids in tin perovskites during annealing, attributed to trapped dimethyl sulfoxide (DMSO) used in film formation. The WPSPS method facilitates accelerated DMSO evaporation, effectively reducing residual DMSO. Interestingly, the WPSPS shifts the energy level of PEDOT:PSS downward, making it more aligned with the perovskite. This alignment enhances the efficiency of charge carrier transport. As the result, tin perovskite film quality is significantly improved, achieving a maximum power conversion efficiency approaching 12% with only an 8.3% efficiency loss after 1700 h of stability tests, which compares well with the state-of-the-art stability of tin-based perovskite solar cells.

Effects of residual dimethyl sulfoxide on the storage performance of nano-TATB

The stability of nano-TATB in an environment of long-term storage or service is currently one concern since it will affect the reliability of weapon systems. To explore the effects of the residual dimethyl sulfoxide (DMSO) solvent generated during synthesis on the storage performance of nano-TATB, this study proposed a new strategy that utilized solvent atmosphere induction to simulate the effects of residual solvents for the first time and quantified the residual solvents using the equilibrium adsorption capacity (Qe) obtained from the pseudo-first-order adsorption kinetic model. Moreover, this study investigated the storage performance of nano-TATB in the DMSO atmosphere using techniques of scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), and infrared (IR) spectroscopy. The results show that the residual DMSO can induce nano-TATB growth more significantly than stimuli in a hot and humid environment. After aging at 60 ​°C for 1 ​d in the DMSO atmosphere, a large number of particles with relatively a regular shape and a particle size of about 1 ​μm were generated in the DMSO atmosphere, with a Qe of DMSO of (1.045 ​± ​0.026) mg·g−1. After aging for 5 ​d, some nano-TATB particles grew and had a particle size of up to 5–6 ​μm, and the average density and cohesive strength of nano-TATB greatly increased. As shown by the analysis of the growth mechanism of nano-TATB in the DMSO atmosphere based on the above experimental results, the main reason for the self-assembly of nano-TATB is the surface DMSO induction caused by the interactions between nano-TATB and DMSO molecules. These results show that the key to improving the storage stability of nano-TATB is to reduce the content of residual solvents.

Rediscovery of poly(ethylene glycol)s as a cryoprotectant for mesenchymal stem cells

BackgroundA medium containing dimethyl sulfoxide (DMSO) (10% v/v) is most widely used for cell cryopreservation at –196 °C. However, residual DMSO consistently raises concerns because of its toxicity; thus, its complete removal process is required.MethodAs biocompatible polymers approved by the Food and Drug Administration for various biomedical applications for humans, poly(ethylene glycol)s (PEGs) with various molecular weights (400, 600, 1 K, 1.5 K, 5 K, 10 K, and 20 K Da) were studied as a cryoprotectant of mesenchymal stem cells (MSCs). Considering the cell permeability difference of PEGs depending on their molecular weight, the cells were preincubated for 0 h (no incubation), 2 h, and 4 h at 37 °C in the presence of PEGs at 10 wt.% before cryopreservation at –196 °C for 7 days. Then, cell recovery was assayed.ResultsWe found that low molecular weight PEGs (400 and 600 Da) exhibit excellent cryoprotecting properties by 2 h preincubation, whereas intermediate molecular weight PEGs (1 K, 1.5 K, and 5 K Da) exhibit their cryoprotecting properties without preincubation. High molecular weight PEGs (10 K and 20 K Da) were ineffective as cryoprotectants for MSCs. Studies on ice recrystallization inhibition (IRI), ice nucleation inhibition (INI), membrane stabilization, and intracellular transport of PEGs suggest that low molecular weight PEGs (400 and 600 Da) exhibit excellent intracellular transport properties, and thus the internalized PEGs during preincubation contribute to the cryoprotection. Intermediate molecular weight PEGs (1 K, 1.5 K, and 5 K Da) worked by extracellular PEGs through IRI, INI, as well as partly internalized PEGs. High molecular weight PEGs (10 K and 20 K Da) killed the cells during preincubation and were ineffective as cryoprotectants.ConclusionsPEGs can be used as cryoprotectants. However, the detailed procedures, including preincubation, should consider the effect of the molecular weight of PEGs. The recovered cells well proliferated and underwent osteo/chondro/adipogenic differentiation similar to the MSCs recovered from the traditional DMSO 10% system.Graphical

Hot-Casting-Assisted Liquid Additive Engineering for Efficient and Stable Perovskite Solar Cells.

High-performance inorganic-organic lead halide perovskite solar cells (PSCs) are often fabricated with a liquid additive such as dimethyl sulfoxide (DMSO), which retards crystallization and reduces roughness and pinholes in the perovskite layers. However, DMSO can be trapped during perovskite film formation and induce voids and undesired reaction byproducts upon later processing steps. Here, it is shown that the amount of residual DMSO can be reduced in as-spin-coated films significantly through use of preheated substrates, or a so-called hot-casting method. Hot casting increases the perovskite film thickness given the same concentration of solutions, which allows for reducing the perovskite solution concentration. By reducing the amount of DMSO in proportion to the concentration of perovskite precursors and using hot casting, it is possible to fabricate perovskite layers with improved perovskite-substrate interfaces by suppressing the formation of byproducts, which increase trap density and accelerate degradation of the perovskite layers. The best-performing PSCs exhibit a power conversion efficiency (PCE) of 23.4% (23.0% stabilized efficiency) under simulated solar illumination. Furthermore, encapsulated devices show considerably reduced post-burn-in decay, retaining 75% and 90% of their initial and post-burn-in efficiencies after 3000h of operation with maximum power point tracking (MPPT) under high power of ultraviolet (UV)-containing continuous light exposure.

In vitro characteristics of cryopreserved platelet concentrates reconstituted by fresh frozen or lyophilized plasma.

Six percent dimethyl sulfoxide (DMSO) cryopreservation of platelet concentrates (PCs) allow longer storage of PCs but require time-consuming post-thaw washing. An alternative process based on removing supernatant before freezing has been implemented in several centres worldwide. We assessed the in vitro characteristics of cryopreserved PCs (CPPs) prepared according to this latest process using either French lyophilized plasma (FLyP) or fresh frozen plasma (FFP) for reconstitution. FLyP provides additional benefits to the process due to its logistical constraints and quick availability. Apheresis PCs (n=16) and buffy coat PCs (n=16) were cryopreserved in 6% DMSO. After storage at -80°C, PCs were thawed and reconstituted with FFP or FLyP. Volume, residual leukocytes, total platelet counts (TPCs), post-thaw recovery, biochemical parameters, and DMSO concentration were assessed. Platelet functions were analysed by swirling index, viscoelastometric assay and CD62P quantification. After reconstitution, TPC was above 2.1011/CPs; recovery was 78±14% with no significant difference between FFP and FLyP. Glucose and lactate levels were not different between plasmas, whereas FLyP-CPPs exhibited a significant increase in LDH and significantly lower pH. Residual DMSO was 8±4G/L. Functional analysis revealed significant differences between FFP and FLyP-CPPs, with lower clot firmness and increased clot initiation. Activation of platelets was not higher in FLyP-CPPs. Preparing CPPs according to this "new" process fulfilled the French legal criteria regardless of the type of plasma. Differences highlighted between FFP-CPPs and FLyP-CPPs were unlikely to be of clinical relevance.

Temperature effects on surface textures of CsPbIBr2 films for perovskite solar cells

The quality of perovskite crystallization directly determines the performance of perovskite solar cells (PSCs). However, there is a lack of research on the bottom crystallization of perovskite films of PSCs. Here, by simply controlling the annealing temperature of perovskite films, CsPbIBr2 films with different surface textures on both the top and bottom sides were obtained, respectively. It is found that dimethyl sulfoxide (DMSO), which is widely used to enhance the crystallization of perovskite films, cannot be completely removed under 160 °C, leading to the formation of snowflower-like textures (SFT) composed of countless pinholes on the upper and lower surfaces of the perovskite film and the existence of obvious cavities between the perovskite layer and the TiO2 layer. This is mainly due to the dissolution of CsPbIBr2 in the residual DMSO. On the contrary, CsPbIBr2 films with compact and smooth surface textures (CST) on both the top and bottom sides can be achieved under 250 °C. For PSCs, the CST-based champion device (9.66%) exhibits higher efficiency and better stability than the SFT-based one (3.69%), primarily due to the high quality film with superior carrier separation and migration properties. The proposed understanding and accurate control of the perovskite crystal growth process are of great significance to the future development of PSCs.

Cd-Based Metal-Organic Framework for Selective Turn-On Fluorescent DMSO Residual Sensing.

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a CdII metal-organic framework (MOF) SXU-4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn-on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@SXU-4), in combination with computational results uncover that the enhanced DMSO-MOF conjugation through multiple DMSO-MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.

Determination of residual dimethyl sulfoxide by high-resolution continuum source graphite furnace molecular absorption spectrometry

High-resolution continuum source molecular absorption spectrometry (HR-CSMAS) has been extended to the determination of sulfur-containing organic molecule, on the example of dimethyl sulfoxide (DMSO) as a residual solvent in CH3NH3PbI3 perovskite thin films. For this purpose, DMSO molecules were converted into CS molecules by pyrolysis in a graphite furnace at low temperature and the sulfur content was determined by measuring molecular absorption of CS at 258.055 nm. An aqueous solution of DMSO was used for calibration. A characteristic mass of 17 ng was achieved for S after pyrolysis at 160 °C by using Pd as a chemical modifier. Furthermore, the content of DMSO was normalized to that of Pb whereas the content of Pb was determined by reducing the Pb in the perovskite to metallic Pb with Zn powder and measuring absorption of the weak Pb line at 261.418 nm by high-resolution continuum source atomic absorption spectrometry (HR-CSAAS). The Pb content remained constant whereas the S/Pb molar ratio decreased with increasing annealing time. Our results open new opportunities for the characterization of residual DMSO in wide classes of materials.

Facile Dissolution of Zein Using a Common Solvent Dimethyl Sulfoxide.

The conformation and stability of zein in solution are closely associated with its solvation process and influence the mechanical properties of the related zein-based materials. In this work, a common solvent dimethyl sulfoxide (DMSO) was used to dissolve zein, rather than solvents frequently used such as aqueous ethanol and acetic acid. It was found that DMSO could dissolve zein readily and the solution was stable for at least 2 weeks. Rheological analysis and small-angle X-ray scattering (SAXS) were employed to characterize the zein DMSO solution. Results of rheological analysis suggested a Huggins coefficient of 0.24, indicating DMSO to be a good solvent for zein. SAXS results revealed that zein adopted an elongated conformation and had dimensions of 2.8 nm × 2.8 nm × 14.8 nm in DMSO solution. Moreover, robust zein films were fabricated from zein DMSO solutions. The content of residual DMSO in the films was determined to be approximately 15 wt % by thermogravimetric analysis, in consistence with the value obtained by other two methods. The film showed a large breaking strain of 320.6% with a considerable breaking stress of 1.9 MPa, yielding a breaking energy of 376.2 MJ/m3. Therefore, the ease of dissolution and good mechanical performance of the final zein-based material make DMSO a potential solvent for fabrication of zein materials, thereby improving the scope of practical applications of zein.

Boosting efficiency of planar heterojunction perovskite solar cells to 21.2% by a facile two-step deposition strategy

The wet lead (II) iodide (PbI2) film-based two-step spin-coating procedure is employed to prepare good-performed planar heterojunction (PHJ) solar cell by simply controlling the remaining content of dimethyl sulfoxide (DMSO) solvent in PbI2 film. It was found that such wet PbI2 film was beneficial to produce pinhole-free, smooth, and highly crystalline perovskite film since the remaining DMSO could retard the crystallization of PbI2. By modulating the content of residual DMSO, the best performed device has efficiency as high as 21.20% with negligible photocurrent hysteresis. The average conversion efficiency has reached 20.15%, 14.42% enhanced comparing to annealing method. Our technique is simple but effective, and we expect it could be widely used especially for devices fabricated on flexible substrates.

Determination of residual dimethylsulphoxide in drug loaded gelatin using thermal desorber – gas chromatography

Traditional headspace – gas chromatography (HS-GC) methods for the determination of residual solvents (RS) start from a homogenous sample solution. Subsequently, it is challenging to determine RS using HS-GC techniques from insoluble solid samples like gelatin which is practically impossible to dissolve or distribute uniformly in water and common organic solvents. In this study, a thermal desorber combined with capillary gas chromatography and flame ionization detection/mass spectrometry (TD-GC-FID/MS) was used for quantitative determination of residual dimethylsulfoxide (DMSO) in gelatin without sample pretreatment. A sample of gelatin was sandwiched between two quartz filter double layers in a polytetrafluoroethylene insert which was then placed in its entirety into a thermal desorption tube. Factors affecting the performance of TD-GC including desorption time, desorption temperature, desorption flow and type of adsorbent were studied by applying a standard solution of DMSO in methanol on a blank gelatin bed. Validation results of the proposed method showed good linearity with an R2-value higher than 0.999 for a wide concentration range and good sensitivity with a limit of detection and limit of quantification of 0.1 μg and 0.2 μg on tube, respectively. The proposed method shows recovery values close to 100%. In addition, a conventional HS-GC method following enzymatic degradation of gelatin was developed to verify the proposed TD-GC method. Both methods were applied for the determination of residual DMSO in gelatin that was loaded with an experimental drug. Results were comparable, but the enzyme assisted HS-GC method was more time consuming and expensive.

Preparation of Vitexin Nanoparticles by Combining the Antisolvent Precipitation and High Pressure Homogenization Approaches Followed by Lyophilization for Dissolution Rate Enhancement

Vitexin, a natural flavonoid found in many medicinal plants, is well known for its rich pharmacological activities. However, the poor water solubility of vitexin has limited its therapeutic application. The aim of this study was to prepare the nanoparticles of vitexin by combining the antisolvent precipitation (ASP) and high pressure homogenization (HPH) approaches followed by lyophilization for improving the dissolution rate of this poorly water-soluble drug. The effects of main factors influencing the mean particle size (MPS) of vitexin were investigated and optimized. Under optimum conditions, vitexin nanosuspensions with an MPS of 80.5 nm were obtained and then lyophilized to form nanoparticles. The obtained vitexin nanoparticles were further characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mass spectrometry (MS), X-ray powder diffraction (XRPD), gas chromatography (GC) and dissolution testing. The results showed that the nanoparticles of vitexin were converted into an amorphous form, with its chemical structure unchanged. Additionally, the residual dimethyl sulfoxide (DMSO) is lower than the International Conference on Harmonization (ICH) limit for class 3 solvents. The dissolution rate of processed vitexin was significantly higher (5.58-fold) than that of raw drug. Overall, the combinative process we developed is an effective way to produce vitexin nanoparticles with markedly enhanced dissolution rate.

Determination of residual dimethylsulfoxide in cryopreserved cardiovascular allografts.

Dimethylsulfoxide (DMSO) is a solvent which protects the structure of allografts during the cryopreservation and thawing process. However, several toxic effects of DMSO in patients after transplantation of cryopreserved allografts have been described. The aim of this study is to determine the residual DMSO in the cardiovascular allografts after thawing and preparation of cryopreserved allografts for clinical application following guidelines of the European Pharmacopoeia for DMSO detection. Four types of EHB allografts (aortic valve-AV, pulmonary valve-PV, descending thoracic aorta-DA, and femoral artery-FA) are cryopreserved using as cryoprotecting solution a 10% of DMSO in medium 199. Sampling is carried out after thawing, after DMSO dilution and after delay of 30min from final dilution (estimated delay until allograft implantation). After progressive thawing in sterile water bath at 37-42°C (duration of about 20min), DMSO dilution is carried out by adding consecutively 33, 66 and 200mL of saline. Finally, tissues are transferred into 200mL of a new physiologic solution. Allograft samples are analysed for determination of the residual DSMO concentration using a validated Gas Chromatography analysis. Femoral arteries showed the most important DMSO reduction after the estimated delay: 92.97% of decrease in the cryoprotectant final amount while a final reduction of 72.30, 72.04 and 76.29% in DMSO content for AV, PV and DA, was found, respectively. The residual DMSO in the allografts at the moment of implantation represents a final dose of 1.95, 1.06, 1.74 and 0.26mgkg-1 in AV, PV, DA and FA, respectively, for men, and 2.43, 1.33, 2.17 and 0.33mgkg-1 for same tissues for women (average weight of 75kg in men, and 60kg in women). These results are seriously below the maximum recommended dose of 1g DMSOkg-1 (Regan et al. in Transfusion 50:2670-2675, 2010) of weight of the patient guaranteeing the safety and quality of allografts.

HPLC-spectrophotometric detection of trace heavy metals via ‘cascade’ separation and concentration

A cascade pre-concentration and separation system involving continuous solid-phase extraction and one-drop solvent concentration was developed to enable high-performance liquid chromatography (HPLC) determination of trace levels of Ni(II), Co(II), Cu(II), Se(IV) and Cr(VI) ions in aqueous solution via complexation with sodium diethyldithiocarbamate. The metal complexes were almost completely adsorbed on the solid phase (octadecylsilyl packed column). Ethyl acetate (eluent) containing the metal complexes was then placed in a centrifuge tube, to which a microvolume of dimethyl sulfoxide (DMSO) was added. Successful pre-concentration of the metal complexes into the DMSO phase was accomplished by removing the ethyl acetate using a compact evaporator in a water bath (40°C); 1000-fold concentration was achieved within 45 min. A portion of the residual DMSO phase was then subjected to HPLC analysis. The proposed method has high reproducibility and high sensitivity with detection limits (3σ) for Ni(II), Co(II), Cu(II), Se(IV) and Cr(VI) ions of 0.08, 0.11, 0.12, 0.44 and 0.20 µg/L, respectively. Relative standard deviations (RSDs) (n = 5) at Ni(II) 5.87 µg/L, Co(II) 5.89 µg/L, Cu(II) 6.35 µg/L, Se(IV) 7.90 µg/L and Cr(VI) 5.20 µg/L (1.0 × 10−7 mol/L each) were 4.0%, 4.6%, 4.6%, 7.2% and 3.4%, respectively.

Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices

Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1μg/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample).

Cross‐Linking of Sulfonated Poly(ether ether ketone) by Thermal Treatment: How Does the Reaction Occur?

AbstractThe cross‐link reaction between macromolecular chains of sulfonated poly(ether ether ketone) (SPEEK) by thermal treatment above 150 °C in presence of dimethylsulfoxide (DMSO) is investigated by various techniques, including elemental analysis, acid‐base titration, infrared spectroscopy, water uptake (WU) measurements, and thermogravimetry. The conditions of thermal treatment are analyzed. The cross‐linking reaction occurs in at least three more or less activated and deactivated positions with different activation energies, leading to different time dependencies of the cross‐link reaction. The role of residual solvent DMSO is studied particularly: the cross‐linking depends significantly on the amount of solvent in the membranes. Implications on WU and thermal stability are of particular importance for the development of high performance proton‐conducting membranes.

PAS‐G supports platelet reconstitution after cryopreservation in the absence of plasma

Platelet (PLT) concentrates frozen in dimethyl sulfoxide (DMSO) can be stored for extended periods at -80°C. PLTs are frozen in a hyperconcentrated state to avoid postthaw washing and minimize residual DMSO. Consequently, PLTs require reconstitution upon thawing. Although plasma, saline, and PLT additive solutions (PASs) have been used to reconstitute frozen PLTs, a comparison to define an optimal solution for PLT recovery has not been performed. DMSO (5% final concentration) was added to buffy coat-derived PLTs, followed by centrifugation to concentrate and freezing at -80°C. Cryopreserved PLTs (n=12 per group) were thawed at 37°C, reconstituted in a unit of thawed frozen plasma, SSP+, or PAS-G. In vitro PLT quality was examined before freezing, immediately after thawing, and 6 and 24 hours after thawing. After thawing and reconstitution, PLTs in plasma and PAS-G displayed similar recovery (69 and 73%, respectively), while PLT recovery in SSP+ was lower (62%). All PLTs maintained an acceptable pH and metabolic activity during postthaw storage. Frozen PLTs were activated, although the extent differed depending on the reconstitution solution, with PLTs in PAS-G retaining better aggregation responses than PLTs in plasma or SSP+. Thawing cryopreserved PLTs in PAS-G, without plasma supplementation, resulted in PLTs with similar recovery and in vitro quality indicators as those suspended in plasma. Importantly, using PAS-G enables the PLTs to be ready for use significantly faster than when having to thaw frozen plasma, which may be beneficial in trauma situations.

Crosslinked SPEEK membranes: Mechanical, thermal, and hydrothermal properties

Abstract

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.

Morphological and degradation studies of sirolimus-containing poly(lactide-co-glycolide) discs

The effect of residual solvent and copolymer ratio on the in vitro degradation and drug release behavior of a bioabsorbable polymer/drug system was investigated in an effort to understand and develop the use of these excipients for controlled drug delivery devices. Sirolimus-containing poly(lactide-co-glycolide) (PLGA) discs were fabricated by a solution-casting method using dimethyl sulfoxide (DMSO) as the solvent. The residual DMSO was removed from a set of discs by supercritical carbon dioxide extraction, and reflections of crystalline sirolimus were observed in the wide-angle X-ray scattering profile observed after extraction. A correlation was not observed between the extent of drug crystallization and extraction conditions and copolymer ratio. Mass loss, molecular weight, and sirolimus release were monitored during an in vitro study of the oven-dried neat PLGA, sirolimus-containing PLGA, and extracted sirolimus-containing PLGA discs during 56 days. The sirolimus-containing PLGA discs with residual DMSO exhibited a faster sirolimus release rate compared to the extracted discs. The residual DMSO facilitated release of sirolimus. The discs that contained PLGA with higher glycolide content, particularly 50% glycolide, degraded faster and exhibited faster sirolimus release.