Potential Cross-contamination Research Articles

ABSENCE OF COVID-19 VIRUS WITHIN AN ACTIVE IVF LABORATORY USING STRICT PATIENT SCREENING AND SAFETY CRITERIA

In the early stages of the COVID-19 pandemic, most IVF clinics stopped the majority of patient treatment cycles to minimize the risk of disease transmission. When ASRM and other professional societies recommended resumption of treatments, procedures were put into place to ensure patient and staff safety. However, the risk of SARS-CoV-2 viral exposure and potential cross contamination within the IVF laboratory remains largely unclear. The objective of this study was to assess the true risk of exposure to SARS-CoV-2 in an active IVF laboratory when strict patient screening procedures are in place.

STATUS QUO – OR IS IT TIME TO RECONSIDER THE VITRIFICATION METHOD RELATIVE TO THE RISK OF EMBRYO DISEASE TRANSMISSION IN CRYOSTORAGE?

The current global pandemic has triggered concerns regarding the potential infectivity of the SARS-CoV-2 virus to blastomeres known to possess ACE-2 receptors. In 2010, Pomeroy and coauthors reviewed the negligible risks associated with the potential cross contamination of human reproductive tissues, gametes and embryos in cryostorage. The purpose of this investigation is to explore changes in ART lab practices over the last decade that could warrant a reassessment of the latter AAB/CRB embryo cryopreservation guidelines relative to disease transmission potential.

In situ SEM/EDS compositional characterization of osteocytes and blood vessels in fossil and extant turtles on untreated bone surfaces; different preservational pathways microns away.

Osteocytes and blood vessels are the main cellular and tissue components of the bone tissue of vertebrates. Evidence of these soft-tissue microstructures has been widely documented in the fossil record of Mesozoic and Cenozoic turtles. However, all these studies have characterized morphologically and elementally these microstructures via isolation from the fossilized bone matrix where they were preserved or in ground sections, which could raise skepticism about the results due to potential cross-contamination or reagents effects. Fossil turtle bones from three different localities with distinct preservation environments and geological settings, including Mongolemys elegans from the Late Cretaceous of Mongolia, Allaeochelys crassesculpta from the Eocene of Germany, and a podocnemidid indet. from the Miocene of Colombia are studied here. Bone from two extant turtle species, Lepidochelys olivacea, and Podocnemis lewyana, as well as a commercial chicken Gallus gallus were used for comparisons. Scanning Electron Microscopy-Energy Dispersive Spectroscopy analyses performed directly on untreated fresh surfaces show that osteocytes-like in the fossil turtle bone are mostly composed of iron and manganese. In contrast, the in situ blood vessels-like of the fossil turtles, as well as those from the extant taxa are rich in elements typically organic in origin (carbon and nitrogen), which are absent to minimally present in the surrounding bone or rock matrix; this suggests a possible endogenous composition for these fossil structures. Also, the results presented here show that although originally both (osteocytes and blood vessels) are organic soft components of bone as evidenced in the extant turtles and chicken, they can experience completely different preservational pathways only microns away from each other in the same fossil bone.

Cryopreservation and IVF in the time of Covid-19: what is the best good tissue practice (GTP)?

Examine good tissue practices as relates to in vitro fertilization, biopsying, and vitrificationto compare current knowledge of ova, sperm, and embryos as vectors for disease transmission as it relates to our current knowledge regarding the SARS-CoV-2 virus.Unknown risks relating to the SARS-CoV-2 virus and sperm, ova, and embryos necessitate a reexamining of how human IVF is performed. Over the last decade, improvements in cryosurvival and live birth outcomes have been associated with zona pellucida breaching procedures (e.g., blastocyst collapsing and biopsying). In turn, today embryos are generally no longer protected by an intact zona pellucida when vitrified and in cryostorage. Additionally, high security storage containers have proven to be resilient to potential cross-contamination and reliable for routine human sperm freezing and embryo vitrification.Several options to current IVF practices are presented that can effectively mitigate the risks of cross-contamination and infection due to the current Covid-19 pandemic or other viral exposures. The question remains; is heightened security and change warranted where the risks of disease transmission likely remain negligible?

Breast Imaging in the Time of COVID-19: A Singapore-based Breast Center's Experience in the Midst of a Pandemic.

The emergence of the COVID-19 pandemic presented new and yet uncharted challenges to the field of radiology, and consequently to breast imaging as a subspecialty. Maintaining a certain standard of care whilst ensuring the safety of patients and staff in our small Singapore-based breast imaging center are equally important and has resulted in modifications of our clinical practice and workflows. Screening patients for COVID-19 symptoms, risk factors, and potential exposure history has become paramount. Workflow changes have also included progressively deferring, and in some cases halting, nonessential services such as biopsies deemed to have a low risk of malignancy, routine follow-up imaging in postoperative patients or those with prior Breast Imaging Reporting and Data System 3 findings, and mammographic screening. Breast radiologists within our practice are also adapting to the changing landscape by playing a more active role in general radiology and emergency department reporting in order to reduce turnaround time and facilitate the discharge of inpatients. We have also enabled a sense of geographical segregation within our breast center to reduce potential exposure and cross-contamination risks. Although the near future remains uncertain, breast imaging within the broader scope of radiology practice will have to continually adjust to meet the ever-changing realities as this pandemic evolves.

Salmonellosis Outbreak Detected by Automated Spatiotemporal Analysis - New York City, May-June 2019.

In May 2019, the New York City Department of Health and Mental Hygiene (NYCDOHMH) detected an unusual cluster of five salmonellosis patients via automated spatiotemporal analysis of notifiable diseases using free SaTScan software (1). Within 1 day of cluster detection, graduate student interviewers determined that three of the patients had eaten prepared food from the same grocery store (establishment A) located inside the cluster area. NYCDOHMH initiated an investigation to identify additional cases, establish the cause, and provide control recommendations. Overall, 15 New York City (NYC) residents with laboratory-diagnosed salmonellosis who reported eating food from establishment A were identified. The most commonly consumed food item was chicken, reported by 10 patients. All 11 clinical isolates available were serotyped as Salmonella Blockley, sequenced, and analyzed by core genome multilocus sequence typing; isolates had a median difference of zero alleles. Environmental assessments revealed food not held at the proper temperature, food not cooled properly, and potential cross-contamination during chicken preparation. Elevated fecal coliform counts were found in two of four ready-to-eat food samples collected from establishment A, and Bacillus cereus was detected in three. The outbreak strain of Salmonella was isolated from one patient's leftover chicken. Establishing automated spatiotemporal cluster detection analyses for salmonellosis and other reportable diseases could aid in the detection of geographically focused, community-acquired outbreaks even before laboratory subtyping results become available.

Transport Coefficients of Ammonia Gas in Thermoplastic Polymers and Nanocomposites Used for Microelectronic Substrates Containers

Polymeric plastic boxes (named Front Opening Unified Pods (FOUP)) were widely used in semiconductor manufacture to maintain the cleanliness of processed wafer substrates in a controlled mini-environment. Polymeric materials, however, are able to sorb airborne molecular contaminants (AMCs) and subsequently to outgas the sorbed AMCs backward to FOUP’s atmosphere, causing the transfer of AMCs to sensitive stored substrates, named cross-contamination. As a type of AMCs, the NH3 cross-contamination could cause a severe yield loss to integrated circuits (crystals (haze), resist-development defects (T-topping) or metallic corrosion). Experiments were carried out to establish the NH3 sorption and desorption kinetics in polyetherimide (PEI), Entegris Barrier Material (EBM)), and EBM/carbon nanotubes (EBMCNT) at NH3 concentration of 800-ppbv, 21°C, and relative humidity of 40%. The transport coefficients i.e. solubility and diffusivity (DNH3 and SNH3) were then determined. The study on NH3 provides an additional guideline to choose the best raw materials for FOUP formulation in taking into account the potential cross-contamination of AMCs. Numerical simulation model based on obtained solubility and diffusivity values was conducted to demonstrate NH3 concentration profiles in FOUP walls during contamination and FOUP decontamination, which are inaccessible by conventional experiments.

Detection and Quantification Methods for Viable but Non-culturable (VBNC) Cells in Process Wash Water of Fresh-Cut Produce: Industrial Validation.

The significance of viable but non-culturable (VBNC) cells in the food industry is not well known, mainly because of the lack of suitable detection methodologies to distinguish them from dead cells. The study aimed at the selection of the method to differentiate dead and VBNC cells of Listeria monocytogenes in process wash water (PWW) from the fruit and vegetable industry. Different methodologies were examined including (i) flow cytometry, (ii) viability quantitative polymerase chain reaction (v-qPCR) using an improved version of the propidium monoazide (PMAxx) dye as DNA amplificatory inhibitor, and (iii) v-qPCR combining ethidium monoazide (EMA) and PMAxx. The results showed that the flow cytometry, although previously recommended, was not a suitable methodology to differentiate between dead and VBNC cells in PWW, probably because of the complex composition of the water, causing interferences and leading to an overestimation of the dead cells. Based on results obtained, the v-qPCR combined with EMA and PMAxx was the most suitable technique for the detection and quantification of VBNC cells in PWW. Concentrations of 10 μM EMA and 75 μM PMAxx incubated at 40°C for 40 min followed by a 15-min light exposure inhibited most of the qPCR amplification from dead cells. For the first time, this methodology was validated in an industrial processing line for shredded lettuce washed with chlorine (10 mg/L). The analysis of PWW samples allowed the differentiation of dead and VBNC cells. Therefore, this method can be considered as a rapid and reliable one recommended for the detection of VBNC cells in complex water matrixes such as those of the food industry. However, the complete discrimination of dead and VBNC cells was not achieved, which led to a slight overestimation of the percentage of VBNC cells in PWW, mostly, due to the complex composition of this type of water. More studies are needed to determine the significance of VBNC cells in case of potential cross-contamination of fresh produce during washing.

A microneedle vaccination with glycoprotein E of Varicella Zoster Virus elicits antibody production and polyfuctional T cells in mice

Abstract A microneedle has several benefits in that it is painless, easy to use and preventable from potential cross-contamination by using conventional needle. Besides these advantages, vaccination with microneedle may provide comparable or even higher immune response than vaccination through conventional intramuscular route. Here we have been developing herpes zoster vaccine using microneedle coated with recombinant glycoprotein E (gE) of VZV, which is essential in virus replication and cell-to-cell spread. Microneedles were coated by gE and three different adjuvants: double-mutant heat-labile toxin (dmLT), the combination of TLR1/2 and TLR3 ligands (Lpampo), or mutant cholera toxin A subunit (CTA). C57BL/6 mice were immunized with the coated microneedles two times at 2-week intervals. The overall increase in gE specific antibody titers was observed among adjuvanted groups compare to the non-adjuvanted group. Moreover, the humoral response was IgG1-dominated. Hence, a decreasing tendency of IgG1/IgG2c ratio was observed in gE adjuvanted with dmLT or Lpampo groups whereas relatively high ratio was detected in CTA group. This indicates that Th1 immune response complemented Th2 response in former groups. By conducting ELISPOT, we measured the amount of IFN-gamma secreting T cells as cell-mediated immune response is significant in immunogenicity of HZ vaccination. Moreover, polyfunctional CD4 T cells were increased after injection with gE +Lpampo coated microneedle. In consistent with humoral response, dmLT or Lpampo adjuvanted group exhibited enhanced cell-mediated immune response. Taken together, delivery of HZ subunit vaccine with microneedle may provide a potent immune response against reactivation of VZV.

Titration of Recombinant Adeno-Associated Virus (rAAV) Genome Copy Number Using Real-Time Quantitative Polymerase Chain Reaction (qPCR).

This protocol is used to determine the concentration of DNase-resistant vector genomes (i.e., packaged in the capsid) in purified recombinant adeno-associated virus (rAAV) preparations. The protocol begins with treatment of the vector stock with DNase I to eliminate unencapsidated AAV DNA or contaminating plasmid DNA. This is followed by a heat treatment to heat-inactivate DNase I, to disrupt the viral capsid, and to release the packaged vector genomes for quantification by real-time polymerase chain reaction (PCR) using a set of standards (linearized plasmid used for vector production) containing known copy numbers. To accomplish high-throughput titration, the primer and probe sets used in real-time PCR are usually designed to target common elements present in most rAAV genomes, such as promoters and poly(A) signals. This strategy significantly reduces the number of PCRs, controls, and turnaround time. Several important controls should be included in the assay as follows: The first two controls should have a known copy number of the rAAV genome plasmid treated or not treated with DNase I. This control tests the effectiveness of DNase treatment. To control for potential cross-contamination between samples during the preparation process, a blank control containing nuclease-free water only should be processed and tested in parallel. A validation vector sample with a known titer should be included in every assay to monitor interassay variability. Finally, for the PCR run, a no-template control (NTC) is included to indicate cross-contamination during PCR setup.

Food safety knowledge and practices among fresh coconut vendors

The study examines the distribution and sale practices of coconut vendors, identifies and analyzes food safety bottlenecks associated with street vending of fresh coconuts in Accra, Ghana. A cluster random sampling technique was used in which the study area was classified into three zones. One hundred fresh coconut vendors responded to a structured questionnaire. The results showed that vendors were predominantly male, most of who were educated up to secondary school level. Many (70.8%) of them learnt the trade through apprenticeship. The vendors were either stationed at a particular location (46.1%), or moved around as itinerant traders (53.8%), with their product displayed on pushcarts or head pans. The respondents revealed that more than 30% of consumers patronize fresh coconut because of its water. Food safety challenges identified in the coconut business include potential cross contamination of packaging materials by fresh coconuts, dipping pared coconut into alum solution to preserve freshness, and improper waste handling during and after sales. Education had a positive influence on food safety knowledge among the fresh coconut vendors (χ2 = 12.8, p < 0.05). Generally, vendors’ knowledge in food safety was encouraging but there ought to be an improvement in these areas of their operations to safeguard the health of consumers.

Design, quality, safety and efficacy of extensively hydrolyzed formula for management of cow's milk protein allergy: What are the challenges?

Cow's milk protein allergy (CMPA) is one of the most common food allergies in infancy. Clinical food allergy guidelines recommend an extensively hydrolyzed formula (EHF) as the first-line treatment in nonbreastfed infants with CMPA. Designing and commercializing EHF poses both technical and regulatory challenges. Each manufacturing step, from sourcing of raw materials to release of the final product, needs to be managed in accordance with comprehensive quality systems. To avoid cross-contamination via externally sourced ingredients, suppliers should be carefully selected based on quality requirements. Strict zoning of the manufacturing areas according to contamination risk and air flow control are effective strategies to prevent accidental allergen contamination. Furthermore, dedicated manufacturing lines for hypoallergenic products are used to prevent potential cross-contamination from other products produced on the same line. The enzymatic hydrolysis, heat treatment and ultrafiltration used are specific to each manufacturer. Consequently, EHF are a heterogenous group of products with differences in the molecular weight profile of peptides, content of residual immunogenic cow's milk allergens, and residual in-vitro allergenicity. These differences are likely to affect clinical efficacy and safety. As not all commercialized EHF products have undergone formal testing in the laboratory and clinical trials, there is a need to develop guidelines for minimum technical and regulatory requirements for EHF products, including validated assays for ongoing quality control. Clinical trials assessing new EHF products for their hypoallergenicity and ability to support normal growth remain the definitive proof of efficacy and safety in infants and young children with CMPA.

Influence of suspension liquid total solids on E. coli O157:H7 survival and transfer efficacy between green tomatoes and cardboard

The objectives of this study were: a) to determine E. coli O157:H7 survival on tomatoes and cardboard squares post-drying, stored at 25 ºC in humidified environment for four days, in buffered peptone water (BPW), and 0.1% diluted peptone (DP); b) to determine pathogen transfer rates (0, 1.5, or 24-hours drying post-inoculation), from inoculated tomato surfaces to uninoculated cardboard squares and conversely; and c) to evaluate SystemSure Plus ATP luminometer for recognizing contamination on visibly soiled (BPW) or visible clean (DP) cardboard. In tomato inoculation studies, E. coli O157:H7 survived better on the fruit when the inoculum was prepared using DP as compared to BPW. The 1.5-hours post drying counts of 5.34 and 5.76 log10 CFU.mL-1 in the rinsate substantially declined to 1.45 and 1.17 log10 CFU.mL-1 on day four, for DP and BPW, respectively. In cardboard inoculation studies, E. coli O157:H7 persisted for four days, with 1.5-hours post-drying counts and day four counts of 4.53 (DP) and 2.55 log10 CFU.mL-1 (BPW), contrary to 3.81 (DP) and 1.92 log10 CFU.mL-1 (BPW). Under the first impression, the slower die-off of E. coli O157:H7 on cardboard questions the possibility of reusing cardboard boxes due to the potential for cross-contamination. In wet transfer (0 hour drying) trials, both tomato-to-cardboard and cardboard-to-tomato yielded 100% positive transfers irrespective of diluent type. Dry transfer (1.5-hours drying interval post inoculation) from tomato-to-cardboard were 100% positive, but no positives were noted when inoculated, dried cardboard was contacted to tomatoes, irrespective of diluent. Results of transfers with BPW as the diluent showed 100% positive transfer from 24-hours dry tomatoes-to-cardboard, as inoculation spots on the tomatoes remained moist due to hygroscopic nature of solutes in BPW. Conversely, only a 40% positive transfer rate was observed under the same conditions with DP as diluent. No positive transfers were recorded from 24-hours dry cardboard-to-tomatoes, irrespective of diluent type. Though E. coli O157:H7 survived better on the surface of cardboard compared to the surface of tomatoes on day four, the dry transfers were more efficient from tomatoes-to-cardboard than conversely, possibly due to smooth and hydrophobic properties of the tomato, and rough and porous surface of the cardboard. ATP luciferase UltrasnapTM swab test showed 9/9 “pass” results for sterile liquid DP and BPW, while 9/9 “fail” results were observed with liquid peptone and BPW contaminated at ca. 9.0 log10 CFU.mL-1E. coli O157:H7. Cardboard squares treated and dried, with sterile DP, showed 8/9 “pass” ATP luciferase results, and 1/9 “warning”, while cardboard squares with contaminated DP showed 9/9 “fail” result. Cardboard squares treated and dried, with sterile BPW, showed 7/9 “pass” ATP luciferase results, and 2/9 “warning”, while cardboard squares with contaminated BPW showed 9/9 “fail” result. Luminometer can simplify detection of microbial load, as well as organic residues, helping to check cardboard boxes for cleanness.

Enhancing produce safety: State estimation-based robust adaptive control of a produce wash system

The rapid introduction of fresh-cut produce into a produce wash system can dramatically decrease the free chlorine (FC) concentration level in the wash water, resulting in potential widespread cross-contamination throughout the entire wash system. To minimize such contamination, a sufficient level of FC must be maintained in the wash water. This paper presents a state estimation-based robust adaptive sliding mode (RASM) control strategy for the wash system to stabilize the FC concentration level during fresh-cut iceberg lettuce washing. This feedback control law for FC dosing is suggested to provide a sufficient FC injection rate (FCIR) to the wash system in order to compensate for the fall in the FC level and in turn to minimize the Escherichia coli (E. coli) O157:H7 levels on washed lettuce and in the wash water. The proposed controller uses the estimated chemical oxygen demand (COD) and FC concentration as feedback signals while system states are estimated by a hybrid extended Kalman filter (HEKF) and the unknown noise statistics are identified by a noise identification (NI) algorithm. Uniformly ultimately boundedness (UUB) of the FC concentration tracking error in the presence of unmodelled dynamics is proven using the Lyapunov framework and Barbalat’s lemma. The E. coli O157:H7 contamination levels are predicted from the joint estimator and controller properties. Simulation results show that the proposed NI-based HEKF/RASM control methodology achieves FC tracking while the pathogens converge to their predicted levels. The E. coli O157:H7 levels decrease as FC concentration increases and in particular, no E. coli O157:H7 is detected when FC concentration is regulated at 15 mg/L. Two robustness tests are performed to show the performance of the proposed controller in the presence of chlorine actuator failure and system parameter uncertainties. Finally, cross-contamination management is examined in terms of the prevalence and mean pathogen levels of incoming pre-wash lettuce in the context of FC regulation at 15 mg/L.

Potential microbial transmission pathways in rural communities using multiple alternative water sources in semi-arid Brazil.

Water scarcity combined with high incidences of diarrhoeal disease amongst many rural communities, suggests that the provision of 'safe' water supplies remains a challenge. Subsequent reliance on multi-source water supplies means that microbial transmission pathways may be numerous and complex. This study aimed to identify and elucidate water supply issues and potential microbial transmission pathways at the household level in rural communities in semi-arid Brazil. Community and sanitary surveys were applied to 99 households from 10 communities located in four municipalities of Paraiba State, Brazil. Moreover, physicochemical and microbial parameters were investigated throughout the water supply chain. High levels of faecal indicator organisms (FIO) were detected in water from Water Storage Reservoirs (WSR) and from in-house Drinking Water Storage Containers (DWSC). A decrease in microbial water quality was observed between water stored within WSR's and DWSC's, suggesting potential cross-contamination at the household level. Several common practices were observed among rural residents, such as the use of collection buckets left unprotected outside on the ground, that may have also contributed to the observed decrease. Schematic diagrams illustrating the complex water supply chains and potential microbial transmission pathways were developed to facilitate identification of effective intervention strategies. Decreases in water supply quality were found to be predominantly caused by cross-contamination within the domestic environment due to several factors, including, a lack of awareness and knowledge of 'safe' collection, handling and storage of water, as well as inadequate sanitation services and/or unhygienic practices. In order to improve public health in such communities, more effort should be directed towards education and training of all stakeholders involved in the water supply chain. This would, certainly, support the successful implementation of further WASH interventions, consequently increasing the likelihood of achieving reduction of excreta-borne diseases.

Precision cancer monitoring using a novel, fully integrated, microfluidic array partitioning digital PCR platform

A novel digital PCR (dPCR) platform combining off-the-shelf reagents, a micro-molded plastic microfluidic consumable with a fully integrated single dPCR instrument was developed to address the needs for routine clinical diagnostics. This new platform offers a simplified workflow that enables: rapid time-to-answer; low potential for cross contamination; minimal sample waste; all within a single integrated instrument. Here we showcase the capability of this fully integrated platform to detect and quantify non-small cell lung carcinoma (NSCLC) rare genetic mutants (EGFR T790M) with precision cell-free DNA (cfDNA) standards. Next, we validated the platform with an established chronic myeloid leukemia (CML) fusion gene (BCR-ABL1) assay down to 0.01% mutant allele frequency to highlight the platform’s utility for precision cancer monitoring. Thirdly, using a juvenile myelomonocytic leukemia (JMML) patient-specific assay we demonstrate the ability to precisely track an individual cancer patient’s response to therapy and show the patient’s achievement of complete molecular remission. These three applications highlight the flexibility and utility of this novel fully integrated dPCR platform that has the potential to transform personalized medicine for cancer recurrence monitoring.

Modeling of Free Chlorine Consumption and Escherichia coli O157:H7 Cross-Contamination During Fresh-Cut Produce Wash Cycles.

Controlling the free chlorine (FC) availability in wash water during sanitization of fresh produce enhances our ability to reduce microbial levels and prevent cross-contamination. However, maintaining an ideal concentration of FC that could prevent the risk of contamination within the wash system is still a technical challenge in the industry, indicating the need to better understand wash water chemistry dynamics. Using bench-scale experiments and modeling approaches, we developed a comprehensive mathematical model to predict the FC concentration during fresh-cut produce wash processes for different lettuce types (romaine, iceberg, green leaf, and red leaf), carrots, and green cabbage as well as Escherichia coli O157:H7 cross-contamination during fresh-cut iceberg lettuce washing. Fresh-cut produce exudates, as measured by chemical oxygen demand (COD) levels, appear to be the primary source of consumption of FC in wash water, with an apparent reaction rate ranging from L/mg·min for all produce types tested, at stable pH levels (6.5 to 7.0) in the wash water. COD levels increased over time as more produce was washed and the lettuce type impacted the rate of increase in organic load. The model parameters from our experimental data were compared to those obtained from a pilot-plant scale study for lettuce, and similar reaction rate constant (5.38 × 10-4 L/mg·min) was noted, supporting our hypothesis that rise in COD is the main cause of consumption of FC levels in the wash water. We also identified that the bacterial transfer mechanism described by our model is robust relative to experimental scale and pathogen levels in the wash water. Finally, we proposed functions that quantify an upper bound on pathogen levels in the water and on cross-contaminated lettuce, indicating the maximum potential of water-mediated cross-contamination. Our model results could help indicate the limits of FC control to prevent cross-contamination during lettuce washing.

Development of BioRad NGC and GE ÄKTA pure systems for highly automated three column protein purification employing tandem affinity, buffer exchange and size exclusion chromatography

Affinity purification, such as Protein A (ProA) followed by size exclusion chromatography (SEC) remains a popular method to obtain research scale proteins. With the need for higher throughput protein production increasing for discovery research, there is substantial interest in the automation of complex protein purification processes, which often start with a ProA step followed by SEC. However, the harsh elution conditions from ProA based chromatography can destabilize some proteins resulting in particulates, which in turn can cause column fouling and potential cross-contamination of subsequent purifications. We modified both Bio Rad NGC and ÄKTA Pure systems to run a three-column process (ProA to buffer exchange to SEC) enabling automated tandem affinity to SEC purification while minimizing the risk of SEC column fouling and subsequent cross-contamination. The intervening buffer exchange column, unlike the final SEC column, can be rapidly regenerated using harsh methods between runs, and these automated systems are capable of processing up to six samples per day without user intervention.

Directed Pinning of Moving Water Droplets on Photoresponsive Liquid Crystal Mats

AbstractCompared to conventional continuous‐flow liquid manipulation, the direct control of liquid droplets on an open surface prevents the potential cross contamination during liquid transfer, which is advantageous for biological microliquids. However, the fabrication techniques of smart surfaces and the fast manipulation of droplets remotely remain difficult, limiting its practical application. Herein, large‐scaled photoresponsive superhydrophobic mats fabricated by the electrospinning of linear liquid crystal polymer are presented. Upon the alternated irradiation of UV–vis light, these mats exhibit significant, fast, and reversible change of adhesion, while their surfaces maintain the superhydrophobicity. Therefore, the water droplets can be pinned at any directed point on the mat surface after the fast superhydrophobic adhesion switch by the remote control of light. It is expected that the active manipulation of discrete droplets on an open surface through these photoresponsive mats provides a new concept for microdroplet manipulation, allowing for minimal reactions among biological samples.

Per‐ and polyfluoroalkyl substances in environmental sampling products: Fact or fiction?

AbstractCan per‐ and polyfluoroalkyl substances (PFAS) be transferred from the common field and other commercial products during sampling? Special handling and care are always advised when collecting samples for PFAS analysis to avoid sample contamination. The potential presence of PFAS in common consumer products and in equipment typically used to collect environmental samples, coupled with the need for very low reporting limits heightens this concern. In this paper, the authors investigate what the potential for cross‐contamination is from a number of commonly used products, with the emphasis on evaluating what the possible worst‐case scenario for cross‐contamination could be. Polytetrafluoroethylene (PTFE), low‐density polyethylene (LDPE), and high‐density polyethylene (HDPE) tubing, pump bladders, and other materials are evaluated along with associated products such as aluminum foil and plastic storage bags. In the experimental design of this study, the products themselves are not analyzed directly for PFAS. Rather, a series of experiments are performed utilizing a leaching procedure to evaluate the potential for cross‐contamination and false‐positive environmental sampling results. This study was performed in a series of experimental batches over the course of a 1‐year period. Analytical results are presented along with experimental observations and recommendations.