[Transformation of scientific research results into teaching resources to improve the teaching effect: taking the teaching of the chromatographic method in the pharmaceutical analysis course as an example].

The pharmaceutical analysis course is a three-dimensional knowledge network that connects several courses to form a new comprehensive knowledge node involving a large knowledge system and flexible knowledge structure. In this course, the subject of chromatography covers a wide range of topics. However, because accurate content is challenging to present, the teaching effect of this subject is poor. In this work, we sought to achieve the educational purpose of establishing morality and cultivating talent, as well as the goal of training highly skilled professionals, by taking the teaching of chromatography in the pharmaceutical analysis course as an example of transforming scientific research results into teaching resources. The resources obtained are integrated into the teaching process to provide innovative and scientific research ideas to students with the aim of not only helping them understand and master technical knowledge but also exercise their ability to raise and solve problems. Furthermore, we expound on how to introduce scientific development frontiers and formulate scientific problems through curriculum design. We also describe how our strategy can promote the teaching effect and achieve teaching objectives. Based on the characteristics of rapid knowledge update and equal emphasis on theory and practice in pharmaceutical analysis, the course is designed by introducing new advances in scientific development, formulating scientific problems, and adopting question- and problem-based learning methods for teaching. The teaching effect is then evaluated through diversified assessment, student feedback, and self-evaluation. The results show that the transformation of scientific research results into teaching resources plays a significant role in stimulating students' interest in learning, improving students' ability to solve problems, and achieving curriculum objectives, all of which greatly improve the teaching effect.

Proceedings of the 2023 Viral Clearance Symposium, Session 3: 2023 VCS New Modalities in Chromatography and Adsorptive Filters.

The session provided an update on the application and mechanistic understanding of intensified unit operations (e.g., mixed mode depth filters, mixed mode AEX) since the last conference in 2019. One of the key gaps identified in the 2019 Viral Clearance Symposium session on the topic was for more investigation required to achieve a clear understanding of the molecular mechanisms of virus removal and the relevance of different moleculés interactions including resin, virus, and product. Further investigation into worst-case conditions for these unit operations is also warranted. One of the key outcomes from that 2019 discussion was also that multimodal anion exchangers can have robust and effective virus removal, depending on process and impurities-an observation that was recapitulated with more specific case studies and evidenced by broader application of these chromatographic resins in late-stage regulatory filings.

Chromatography affinity resin with photosynthetically-sourced protein A ligand.

Green, photosynthesizing plants can be proficiently used as cost-effective, single-use, fully biodegradable bioreactors for environmentally-friendly production of a variety of valuable recombinant proteins. Being near-infinitely scalable and most energy-efficient in generating biomass, plants represent profoundly valid alternatives to conventionally used stationary fermenters. To validate this, we produced a plastome-engineered tobacco bioreactor line expressing a recombinant variant of the protein A from Staphylococcus aureus, an affinity ligand widely useful in antibody purification processes, reaching accumulation levels up to ~ 250 mg per 1 kg of fresh leaf biomass. Chromatography resin manufactured from photosynthetically-sourced recombinant protein A ligand conjugated to agarose beads demonstrated the innate pH-driven ability to bind and elute IgG-type antibodies and allowed one-step efficient purification of functional monoclonal antibodies from the supernatants of the producing hybridomas. The results of this study emphasize the versatility of plant-based recombinant protein production and illustrate its vast potential in reducing the cost of diverse biotechnological applications, particularly the downstream processing and purification of monoclonal antibodies.

A Rapid, Equipment-Free DNA Isolation Method for DNA Barcoding.

This rapid, equipment-free DNA isolation procedure using chromatography paper is a simple method that can be performed in less than 30 min and requires no wet lab experience. With minimal expense, it offers an affordable alternative for anyone wanting to explore biodiversity. It also provides an excellent option for use in classrooms or other activities that are time limited. The method works best for plants or lichens, producing stable DNA on Whatman® chromatography paper at room temperature, which can be eluted as needed.

Isolation of Extracellular Outer Membrane Vesicles (OMVs) from Escherichia coli Using EVscore47 Beads.

Outer membrane vesicles (OMVs) are attractive for biomedical applications based on their intrinsic properties in relation to bacteria and vesicles. However, their widespread use is hampered by low yields and purities. In this study, EVscore47 multifunctional chromatography microspheres were synthesized and used to efficiently isolate functional OMVs from Escherichia coli. Through this technology, OMV loss can be kept to a minimum, and OMVs can be harvested using EVscore47 at 11-fold higher yields and ~13-fold higher purity than those achieved by means of ultracentrifugation. Based on the results presented here, we propose a novel EVscore47-based isolation of OMVs that is fast and scalable.

Evaluation of Physicochemical Properties of Ipsapirone Derivatives Based on Chromatographic and Chemometric Approaches.

Drug discovery is a challenging process, with many compounds failing to progress due to unmet pharmacokinetic criteria. Lipophilicity is an important physicochemical parameter that affects various pharmacokinetic processes, including absorption, metabolism, and excretion. This study evaluated the lipophilic properties of a library of ipsapirone derivatives that were previously synthesized to affect dopamine and serotonin receptors. Lipophilicity indices were determined using computational and chromatographic approaches. In addition, the affinity to human serum albumin (HSA) and phospholipids was assessed using biomimetic chromatography protocols. Quantitative Structure-Retention Relationship (QSRR) methodologies were used to determine the impact of theoretical descriptors on experimentally determined properties. A multiple linear regression (MLR) model was calculated to identify the most important features, and genetic algorithms (GAs) were used to assist in the selection of features. The resultant models showed commendable predictive accuracy, minimal error, and good concordance correlation coefficient values of 0.876, 0.149, and 0.930 for the validation group, respectively.

Establishment of a graphene oxide-assisted nucleic acid chromatography strip detection technology for Prorocentrum minimum.

In recent decades, the harmful algal blooms (HABs) caused by Prorocentrum minimum have caused serious environmental damage and economic losses. The detection of P. minimum plays an important role in warning the outbreak of P. minimum-forming HABs. By utilizing the powerful absorption of graphene oxide (GO) on short-stranded DNA, a GO-assisted nucleic acid chromatography strip (GO-NACS) was proposed here to achieve a highly sensitive, specific, intuitive, and convenient detection of P. minimum. In particular, this study used our previously reported conventional-NACS (C-NACS) as a control to evaluate the improvement of detection performance with the use of GO. The performance of GO-NACS was evaluated from the perspectives of specificity, sensitivity, stability, and practicality. The specificity test demonstrated that it had a high degree of specificity and did not display cross-reacting with non-target algal species. The sensitivity test with the genomic DNA indicated that it had a detection limit of 1.30 × 10-3 ng µL-1, representing a 10-fold higher sensitivity than C-NACS and a 100-fold higher sensitivity than agarose gel electrophoresis (AGE). The interference test with non-target algal species demonstrated that it had a good detection stability, and the interfering algal species had no obvious effect on the detection of P. minimum. The practicality test with simulated natural water samples showed that the cellular detection limit of GO-NACS was 6.8 cells mL-1, which was 10-fold and 100-fold lower than that of C-NACS and AGE, respectively. In conclusion, the established GO-NACS may offer a novel alternative technique for the detection of P. minimum while guaranteeing specificity and enhancing sensitivity without requiring extensive apparatus.

Chromatography based profiling of feruloylated arabinans and galactans.

Profiling of pectic arabinans and galactans by analysis of the released oligosaccharides after backbone cleavage provides information on the complexity of the polymer structure. In plants of the family Amaranthaceae, arabinan and galactan substitution with ferulates extends the polysaccharide complexity, changing its chemical properties. Knowledge of the ferulate environment is crucial to understand structure-function-relationships of feruloylated pectins. Here, we present an approach to separate enzymatically generated feruloylated and non-feruloylated arabino- and galactooligosaccharides, followed by deesterification and semiquantitative analysis by HPAEC-PAD using previously reported relative response factors. Application of this approach to sugar beet pectins and insoluble and soluble dietary fiber preparations of amaranth and quinoa suggests that ferulates are preferably incorporated into more complex structures, as nicely demonstrated for feruloylated galactans. Also, ferulate substitution appears to negatively affect enzymatic cleavage by using endo-enzymes. As a consequence, we were able to tentatively identify new feruloylated tri- and tetrasaccharides of galactans isolated from sugar beet pectins.

Nanoconfined Electrokinetic Chromatography (NEC): Gradient Separation and Sensing of Short DNA Fragments at the Single-Molecule Level.

Glass nanopipets have been demonstrated to be a powerful tool for the sensing and discrimination of biomolecules, such as DNA strands with different lengths or configurations. Despite progress made in nanopipet-based sensors, it remains challenging to develop effective strategies that separate and sense in one operation. In this study, we demonstrate an agarose gel-filled nanopipet that enables hyphenated length-dependent separation and electrochemical sensing of short DNA fragments based on the electrokinetic flow of DNA molecules in the nanoconfined channel at the tip of the nanopipet. This nanoconfined electrokinetic chromatography (NEC) method is used to distinguish the mixture of DNA strands without labels, and the ionic current signals measured in real time show that the mixed DNA strands pass through the tip hole in order according to the molecular weight. With NEC, gradient separation and electrochemical measurement of biomolecules can be achieved simultaneously at the single-molecule level, which is further applied for programmable gene delivery into single living cells. Overall, NEC provides a multipurpose platform integrating separation, sensing, single-cell delivery, and manipulation, which may bring new insights into advanced bioapplication.

On the contribution of the top and bottom walls in micro-pillar array columns and related high-aspect ratio chromatography systems.

We report on a steady-state based, and hence highly accurate numerical modelling study of the effect of the top and bottom wall in the current generation of micro-pillar array columns. These have a mesoporous retention layer that not only covers the pillar walls but also the bottom wall. Our results show that the performance of these columns can in general not be improved by also covering the top wall with the same layer, despite the increased column symmetry this approach would offer. The reason for this is that the local species retardation caused by a retentive layer is much stronger than the pure flow arresting effect of an uncovered wall. At least, this has a crucial impact in high aspect-ratio systems such as micro-pillar array columns because these require a small inter-pillar distance to promote mass transfer together with a large channel depth to enable a sufficiently high flow rate. On the other hand, a notable improvement could be made if micro-pillar array would be produced without having a retentive layer at the bottom. At Péclet number Pe = 50 and aspect ratio AR = 5 for flow-channels, this gain amounts up to about 4.5 h-units at a zone retention factor k'' = 2 and 1.75 h-units at k'' = 16 (gain scales almost linearly with Pe). To verify these results, we also considered another high aspect-ratio system with a simplified geometry: the open-tubular channel with a flat-rectangular cross-section. This led to very similar observations, thus confirming the findings for the micro-pillar array. The results produced in the present study also allow us to conclude that the classic modelling paradigm adopted in chromatography, which is based on the independency and hence additivity of the hCm- and hCs-contributions, can lead to large modelling errors in chromatographic systems with a high aspect-ratio, even when their geometry is so simple as that of a straight open-tubular channel with constant cross-section. Indeed, when both zones are treated independently, the analysis misses how the vertical diffusion through the retentive layer helps suppressing the vertical gradients in the mobile zone. The diffusion through this layer occurs in a ratio of k''Ds/Dm (Dm being the diffusion coefficient in mobile phase zone and Ds being the diffusion coefficient in stationary phase zone), such that at high retention factors this diffusion contribution even becomes the dominant one.

[Determination of organic acids and anions in exhaled breath by condensation collection-ion chromatography].

A non-invasive condensation collection-ion chromatography method was established for the determination of organic acids and anions including lactic acid, formic acid, acetic acid, pyruvic acid, chloride, nitrate, nitrite, and sulfate in the exhaled breath of humans. The breath exhaled was condensed and collected using a home-made exhaled breath condensation equipment. This equipment included a disposable mouthpiece as a blow-off port, one-way valve and flow meter, cold trap, disposable condensate collection tube placed in the cold trap, and gas outlet. A standard sampling procedure was used. Before collection, the collection temperature and sampling volume were set on the instrument control panel, and sampling was started when the cold-trap temperature dropped to the set value, while maintaining the balance. Subjects were required to gargle with pure water before sampling. During the sampling process, the subjects were required to inhale deeply until the lungs were full of gas and then exhale evenly through the air outlet. When the set volume was collected, the instrument made a prompt sound; then, the collection was immediately ended, the expiration time was recorded, and the average collection flow was calculated according to the expiration time and sampling volume. After collection, the disposable condensation collection tube was immediately taken out, sealed, and stored in the refrigerator at -20 ℃ away from light, and immediately used for further testing. The organic acids and anions in exhaled breath condensation (EBC) were filtered through a 0.22 µm membrane filter before injection and detected by ion chromatography with conductivity detection. Factors such as collection temperature and collection flow rate during condensation collection were optimized. The optimal cooling temperature was set at -15 ℃, and the optimal exhaled breath flow rate was set at 15 L/min. The mobile phase consisted of a mixture of sodium carbonate (1.5 mmol/L) and sodium bicarbonate (3 mmol/L). The flow rate was 0.8 mL/min, and the injection volume was 100 µL. An IC-SA3 column (250 mm×4.0 mm) was used, and the temperature was set at 45 ℃. An ICDS-40A electrodialysis suppressor was used, and the current was set at 150 mA. The linear ranges of the eight organic acids and anions were 0.1-10.0 mg/L; their correlation coefficients (r) were ≥0.9993. The limits of detection (LODs) for the eight organic acids and anions were 0.0017-0.0150 mg/L based on a signal-to-noise ratio of 3, and the limits of quantification (LOQs) were 0.0057-0.0500 mg/L based on a signal-to-noise ratio of 10. The intra-day precisions were 5.06%-6.33% (n=5), and the inter-day precisions were 5.37%-7.50% (n=5). This method was used to detect organic acids and anions in the exhaled breath of five healthy subjects. The contents of organic acids and anions in the exhaled breath were calculated. The content of lactic acid was relatively high, at 1.13-42.3 ng/L, and the contents of other seven organic acids and anions were 0.18-11.0 ng/L. During a 10 km-long run, the majority of organic acids and anions in the exhaled breath of five subjects first increased and then decreased. However, due to abnormal metabolism, the content changes of lactic acid, acetic acid, pyruvic acid and chloride in one subject were obviously different from others during exercise, showing a continuous rise. This method has the advantages of involving a simple sampling process and exhibiting good precision, few side effects, and no obvious discomfort or risk to the subjects. This study provides experimental ideas and a theoretical basis for future research on human metabolites.

[Ion chromatography for the determination of n-butylamine in the workplace air].

Objective: To establish a method for the determination of n-butylamine in the air of the workplace by ion chromatography. Methods: In February 2022, on-site sampling was carried out using an atmospheric sampler. N-butylamine was adsorbed by a neutral silica gel tube and then performed for qualitative and quantitative determination by ion chromatography after ultrasonic desorption with 10 mmol/L sulfuric acid solution. Results: The linear range of the method was 0.0375-100.0 µg/ml, the linear equation of the standard curve was y=0.0713x-0.0327, the correlation coefficient was 0.9992. The detection limit of the method was 11.25 µg/L, and the lower limit of quantification was 37.50 µg/L, the lowest quantitative concentration was 0.025 mg/m(3) (in term of sampling 7.5 L). The average desorption efficiency of the method was 91.50%-95.38%, the precision was 1.10%-2.30%, the standard recovery was 83.83%-100.02%, sampling efficiency was 100.00%. Conclusion: This method is fast, sensitive and accurate, and can be used for the determination of n-butylamine in the air of workplace.

Small-Angle X-Ray Scattering for Macromolecular Complexes.

Small angle X-ray scattering (SAXS) is a versatile technique that can provide unique insights in the solution structure of macromolecules and their complexes, covering the size range from small peptides to complete viral assemblies. Technological and conceptual advances in the last two decades have tremendously improved the accessibility of the technique and transformed it into an indispensable tool for structural biology. In this chapter we introduce and discuss several approaches to collecting SAXS data on macromolecular complexes, including several approaches to online chromatography. We include practical advice on experimental design and point out common pitfalls of the technique.

Novel purification platform based on multimodal preparative scale separation of mAb fragments and aggregates.

Monoclonal antibodies (mAbs) continue to dominate the biopharmaceutical industry. Certain mAbs are prone to fragmentation and clipping and in these cases, adequate removal of these species is critical during manufacturing. Fragments can be generated during fermentation, purification, storage, formulation, and administration. Their addition to the acidic charge-variant of the purified mAb has been reported to decrease stability and potency of the final product. However, contrary to mAb aggregation, manufacturers have not given much attention to removal of fragments and clipped species and as a result most conventional mAb platforms offer at best limited capabilities for their removal. In this study, we propose a novel purification platform that uses multimodal chromatography and achieves complete removal of a range of mAb fragments and clipped products (25-120 kDa). The utility of the platform has been successfully demonstrated for 2 IgG1s and 2 IgG4s. Further, adequate removal of the various host cell impurities such as host cell proteins (<10 ppm) and host cell DNA (<5 ppb) has been achieved. Finally, the platform was able to deliver adequate removal of high molecular weight impurities (<1 %) and a 30 % clearance of the acidic charge variant. The proposed single step has been shown to deliver what the polishing chromatography and intermediate purification chromatography steps deliver in a traditional mAb platform.

Separation of the diastereomers of phosphorothioated siRNAs by anion-exchange chromatography under non-denaturing conditions.

In recent years, several small interfering RNA (siRNA) therapeutics have been approved, and most of them are phosphorothioate (PS)-modified for improving nuclease resistance. This chemical modification induces chirality in the phosphorus atom, leading to the formation of diastereomers. Recent studies have revealed that Sp and Rp configurations of PS modifications of siRNAs have different biological properties, such as nuclease resistance and RNA-induced silencing complex (RISC) loading. These results highlight the importance of determining diastereomeric distribution in quality control. Although various analytical approaches have been used to separate diastereomers (mainly single-stranded oligonucleotides), it becomes more difficult to separate all of them as the number of PS modifications increases. Despite siRNA exhibits efficacy in the double-stranded form, few reports have examined the separation of diastereomers in the double-stranded form. In this study, we investigated the applicability of non-denaturing anion-exchange chromatography (AEX) for the separation of PS-modified siRNA diastereomers. Separation of the four isomers of the two PS bonds tended to improve in the double-stranded form compared to the single-stranded form. In addition, the effects of the analytical conditions and PS-modified position on the separation were evaluated. Moreover, the elution order of the Sp and Rp configurations was confirmed, and the steric difference between them, i.e., the direction of the anionic sulfur atom, appeared to be important for the separation mechanism in non-denaturing AEX. Consequently, all 16 peak tops of the four PS modifications were detected in one sequence, and approximately 30 peak tops were detected out of 64 isomers of six PS bonds, indicating that non-denaturing AEX is a useful technique for the quality control of PS-modified siRNA therapeutics.

Preparation of small peptoid-modified zwitterion-exchange/reversed-phase mixed-mode chromatography stationary phases for the separation of arenes and antibiotics.

In this study, three small peptoids with different structures, named Sil-peptoids, were developed to improve the separation selectivity of zwitterion-exchange/reversed-phase mixed-mode chromatography stationary phases for multi-component complex drugs. Nonpolar, amphoteric, and alkaline drugs were used as test samples to demonstrate their retention behaviors in reversed-phase, ionic, and mixed-mode interactions. It was observed that different carboxyl anions in the small peptoids of the Sil-peptoids had vast differences in their stereo-selectivity. The stereo-selectivity and the influence of Sil-peptoids on the retention behavior of complex drugs and their interaction mechanism for the drug molecules were effectively evaluated through the combination of chromatographic analysis and molecular modeling. Finally, a mixture of drugs consisting of two polar and six non-polar drugs was used to obtain a separation effect with a resolution >1.5. Two other groups of polar antibiotics were used to verify the separation ability of the Sil-peptoids. The results indicated that the Sil-peptoids could separate multiple substances simultaneously. These novel stationary phases can be applied to the analysis of complex multi-component drugs.

Design and characterization of an electrochemically-modulated membrane chromatography device.

Membrane separations offer a compelling alternative to traditional chromatographic methods by overcoming mass transport limitations. We introduce an additional degree of freedom in modulating membrane chromatography by using metalized membranes in a potential-driven process. Investigating the impact of a gold coating on membrane characteristics, the sputtered gold layer enhances the surface conductivity with stable electrochemical behavior. However, this comes at the expense of reduced permeability, wettability, and static binding capacity (∼ 474 µg g-1 of maleic acid). The designed device displayed a homogenous flow distribution, and the membrane electrodes exhibit predominantly capacitive behavior during potential application. Modulating the electrical potential during the adsorption and desorption phase strongly influenced the binding and elution behavior of anion-exchange membranes. Switching potentials between ±1.0 V vs. Ag/AgCl induces desorption, confirming the process principle. Elution efficiency reaches up to 58 % at -1.0 V vs. Ag/AgCl in the desorption phase without any alteration of the mobile phase. Increasing the potential perturbation ranging from +1.0 V to -1.0 V vs. Ag/AgCl resulted in reduced peak width and improved elution behavior, demonstrating the feasibility of electrochemically-modulated membrane chromatography. The developed process has great potential as a gentle and sustainable separation step in the biotechnological and chemical industry.

Explainable deep learning enhances robust and reliable real-time monitoring of a chromatographic protein A capture step.

The application of model-based real-time monitoring in biopharmaceutical production is a major step toward quality-by-design and the fundament for model predictive control. Data-driven models have proven to be a viable option to model bioprocesses. In the high stakes setting of biopharmaceutical manufacturing it is essential to ensure high model accuracy, robustness, and reliability. That is only possible when (i) the data used for modeling is of high quality and sufficient size, (ii) state-of-the-art modeling algorithms are employed, and (iii) the input-output mapping of the model has been characterized. In this study, we evaluate the accuracy of multiple data-driven models in predicting the monoclonal antibody (mAb) concentration, double stranded DNA concentration, host cell protein concentration, and high molecular weight impurity content during elution from a protein A chromatography capture step. The models achieved high-quality predictions with a normalized root mean squared error of <4% for the mAb concentration and of ≈10% for the other process variables. Furthermore, we demonstrate how permutation/occlusion-based methods can be used to gain an understanding of dependencies learned by one of the most complex data-driven models, convolutional neural network ensembles. We observed that the models generally exhibited dependencies on correlations that agreed with first principles knowledge, thereby bolstering confidence in model reliability. Finally, we present a workflow to assess the model behavior in case of systematic measurement errors that may result from sensor fouling or failure. This study represents a major step toward improved viability of data-driven models in biopharmaceutical manufacturing.

A comparative study of the predictive performance of different descriptor calculation tools: Molecular-based elution order modeling and interpretation of retention mechanism for isomeric compounds from METLIN database.

In the pharmaceutical industry, the need for analytical standards is a bottleneck for comprehensive evaluation and quality control of intermediate and end products. These are complex mixtures containing structurally related molecules. In this regard, chromatographic peak annotation, especially for critical pairs of isomers and closest structural analogs, can be supported by using a Quantitative Structure Retention Relationship (QSRR) approach. In our study, we investigated the fundamental basis of the reversed-phase (RP) retention mechanism for 1141 isomeric compounds from the METLIN SMRT dataset. Nine different descriptor calculation tools combined with different feature selection methods (genetic algorithm (GA), stepwise, Boruta) and machine learning (ML) approaches (support vector machine (SVM), multiple linear regression (MLR), random forest (RF), XGBoost) were applied to provide a reliable molecular structure-based interpretation of RP retention behaviour of the isomeric compounds. Strict internal and external validation metrics were used to select models with the best predictive capabilities (rtest > 0.73, order of elution > 60 %). For the developed models, mean absolute errors were in the range of 60 to 110 s. Stepwise and GA showed the most suitable performance as descriptor selection methods, while SVM and XGBoost modeling gave satisfactory predictive characteristics in most cases. Validation performed on the published experimental data for structurally related pharmaceutical compounds confirmed the best accuracy of MLR modeling in combination with GA feature selection of general physico-chemical properties. The resulting models will be useful for the prediction of separation and identification of structurally related compounds in pharmaceutical analysis, providing a simultaneous understanding of the interaction mechanisms leading to their retention under RP conditions.