Engaging Early-Career Scientists in Global Policy-Making

Pressing global challenges, such as climate change, the COVID-19 pandemic, or antibiotic resistance, require coordinated international responses guided by evidence-informed decisions. For this purpose, it is critical that scientists engage in providing insights during the decision-making process. However, the mechanisms for the engagement of scientists in policy-making are complex and vary internationally, which often poses significant challenges to their involvement. Herein, we address some of the mechanisms and barriers for scientists to engage in policy-making with a global perspective by early-career scientists. We highlight the importance of scientific academies, societies, universities, and early-career networks as stakeholders and how they can adapt their structures to actively contribute to shaping global policies, with representative examples from chemistry-related disciplines. We showcase the importance of raising awareness, providing resources and training, and leading discussions about connecting emerging scientists with global decision-makers to address societal challenges through policies.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading

Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethylenimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and we describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the stress response of plants to polymer-based nanomaterials and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading

Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethylenimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and we describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the stress response of plants to polymer-based nanomaterials and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Carbon nanotube biocompatibility in plants is determined by their surface chemistry

BACKGROUND

Agriculture faces significant global challenges including climate change and an increasing food demand due to a growing population. Addressing these challenges will require the adoption of transformative innovations into biotechnology practice, such as nanotechnology. Recently, nanomaterials have emerged as unmatched tools for their use as biosensors, or as biomolecule delivery vehicles. Despite their increasingly prolific use, plant-nanomaterial interactions remain poorly characterized, drawing into question the breadth of their utility and their broader environmental compatibility.

RESULTS

Herein, we characterize the response of Arabidopsis thaliana to single walled carbon nanotube (SWNT) exposure with two different surface chemistries commonly used for biosensing and nucleic acid delivery: oligonucleotide adsorbed-pristine SWNTs, and polyethyleneimine-SWNTs loaded with plasmid DNA (PEI-SWNTs), both introduced by leaf infiltration. We observed that pristine SWNTs elicit a mild stress response almost undistinguishable from the infiltration process, indicating that these nanomaterials are well-tolerated by the plant. However, PEI-SWNTs induce a much larger transcriptional reprogramming that involves stress, immunity, and senescence responses. PEI-SWNT-induced transcriptional profile is very similar to that of mutant plants displaying a constitutive immune response or treated with stress-priming agrochemicals. We selected molecular markers from our transcriptomic analysis and identified PEI as the main cause of this adverse reaction. We show that PEI-SWNT response is concentration-dependent and, when persistent over time, leads to cell death. We probed a panel of PEI variant-functionalized SWNTs across two plant species and identified biocompatible SWNT surface functionalizations.

CONCLUSIONS

While SWNTs themselves are well tolerated by plants, SWNTs surface-functionalized with positively charged polymers become toxic and produce cell death. We use molecular markers to identify more biocompatible SWNT formulations. Our results highlight the importance of nanoparticle surface chemistry on their biocompatibility and will facilitate the use of functionalized nanomaterials for agricultural improvement.

Advances in engineering near-infrared luminescent materials

Near-infrared (NIR) luminescent materials have emerged as a growing field of interest, particularly for imaging and optics applications in biology, chemistry, and physics. However, the development of materials for this and other use cases has been hindered by a range of issues that prevents their widespread use beyond benchtop research. This review explores emerging trends in some of the most promising NIR materials and their applications. In particular, we focus on how a more comprehensive understanding of intrinsic NIR material properties might allow researchers to better leverage these traits for innovative and robust applications in biological and physical sciences.

Nanotechnology to advance CRISPR-Cas genetic engineering of plants

CRISPR-Cas genetic engineering of plants holds tremendous potential for providing food security, battling biotic and abiotic crop stresses caused by climate change, and for environmental remediation and sustainability. Since the discovery of CRISPR-Cas technology, its usefulness has been demonstrated widely, including for genome editing in plants. Despite the revolutionary nature of genome-editing tools and the notable progress that these tools have enabled in plant genetic engineering, there remain many challenges for CRISPR applications in plant biotechnology. Nanomaterials could address some of the most critical challenges of CRISPR genome editing in plants through improvements in cargo delivery, species independence, germline transformation and gene editing efficiency. This Perspective identifies major barriers preventing CRISPR-mediated plant genetic engineering from reaching its full potential, and discusses ways that nanoparticle technologies can lower or eliminate these barriers. We also describe advances that are needed in nanotechnology to facilitate and accelerate plant genome editing. Timely advancement of the application of CRISPR technologies in plant engineering is crucial for our ability to feed and sustain the growing human population under a changing global climate.

The effects of cognitive impairment and substance abuse on psychiatric hospitalizations

Previous studies have demonstrated a relationship between impairment in executive functioning and hospital and community tenure for people with schizophrenia. However, while it has been clearly established that comorbid substance abuse has a profound negative impact on the functioning of people with schizophrenia, no studies have examined the relative effect of cognitive impairment to substance use in predicting rehospitalization in this population. The present study examined the extent to which impairment on the Wisconsin Card Sorting Test (WCST) and substance abuse are correlated with lifetime psychiatric hospitalizations for outpatients with schizophrenia. Substance abuse was a significant predictor of prior hospitalizations and impairment on the WCST was a significant predictor of the months hospitalized. The findings suggest that both substance abuse and cognitive impairment need to be addressed in order to reduce hospitalizations and time in the hospital.

Oxidant-mediated repression of mitochondrial transcription in diabetic rats

Diabetes-associated mitochondrial dysfunction is recognized, but the underlying mechanisms are unknown. Using isolated liver mitochondria from streptozotocin-induced diabetic Sprague-Dawley rats, we showed that diabetes can result in a > 95% loss in mitochondrial transcriptional capacity. Decreased transcription correlated well with both disease status, as indicated by serum lipemia and ketone levels, and with increased resistance of the mitochondrial transcription system to oxidative stress imposed by the hydrophilic AAPH [2,2'-azobis-(2-amidino-propane) hydrochloride] or the hydrophobic AMVN [2,2'-azobis-(2,4,-dimethyl-valeronitrile)]. The onset of AAPH- or AMVN-induced lipid peroxidation was also delayed; this suggests that liver mitochondrial membranes from diabetics have increased resistance to peroxyl radical-mediated lipid peroxidation. Lipid peroxidation induced endogenously was increased, however, suggesting a state of increased oxidative stress likely exists in vivo. Furthermore, changes in the rate of lipid peroxidation occurring during the propagation phase were also affected by diabetes. This implies possible changes in lipid composition or structure. Analysis indicated that the factors protecting mitochondria from lipid peroxidation differ from those involved in protecting the transcription system, and that both are independent of free radical scavenger levels. These results suggested that diabetes alters mitochondrial exposure and/or response to reactive species and provided clues to the role of oxidant stress in the development of diabetes-associated mitochondrial dysfunction.

Defects at center P underlie diabetes-associated mitochondrial dysfunction

Detailed respiration studies on isolated liver mitochondria from streptozotocin-induced diabetic Sprague-Dawley rats revealed a disease-associated decrease in the ADP/O ratio, a marker for mitochondrial ability to couple the consumption of oxygen to the phosphorylation of ADP. This decrease was observed following induction of respiration with glutamate/malate, succinate, or duroquinol, which enter the electron transport chain selectively at complexes I (NADH dehydrogenase), II (succinate dehydrogenase), or III (cytochrome bc1 complex), respectively. These data, coupled with studies using respiratory inhibitors (most importantly antimycin A and myxothiazol), localize at least a portion of this defect to a single site within the electron transport chain (center P in the Q-cycle portion of complex III). These results suggest that liver mitochondria from diabetic animals may generate increased levels of reactive oxygen species at the portion of the electron transport chain already established as the major site of mitochondrial free radical generation. The reduction in the ADP/O ratio occurred in mitochondria that do not have overt defects in the respiratory control ratio or in State 3 and State 4 respiration. The data in this paper suggest that defects in center P of the electron transport chain likely increase mitochondrial exposure to oxidants in the diabetic. This data may partially explain the evidence of altered exposure and/or response to reactive species in mitochondria from diabetics. This work thus provides further clues to the interaction between oxidative stress and diabetes-associated mitochondrial dysfunction.

Modulation of cellular and viral promoters by mutant human p53 proteins found in tumor cells

Wild-type p53 has recently been shown to repress transcription from several cellular and viral promoters. Since p53 mutations are the most frequently reported genetic defects in human cancers, it becomes important to study the effects of mutations of p53 on promoter functions. We, therefore, have studied the effects of wild-type and mutant human p53 on the human proliferating-cell nuclear antigen (PCNA) promoter and on several viral promoters, including the herpes simplex virus type 1 UL9 promoter, the human cytomegalovirus major immediate-early promoter-enhancer, and the long terminal repeat promoters of Rous sarcoma virus and human T-cell lymphotropic virus type I. HeLa cells were cotransfected with a wild-type or mutant p53 expression vector and a plasmid containing a chloramphenicol acetyltransferase reporter gene under viral (or cellular) promoter control. As expected, expression of the wild-type p53 inhibited promoter function. Expression of a p53 with a mutation at any one of the four amino acid positions 175, 248, 273, or 281, however, correlated with a significant increase of the PCNA promoter activity (2- to 11-fold). The viral promoters were also activated, although to a somewhat lesser extent. We also showed that activation by a mutant p53 requires a minimal promoter containing a lone TATA box. A more significant increase (25-fold) in activation occurs when the promoter contains a binding site for the activating transcription factor or cyclic AMP response element-binding protein. Using Saos-2 cells that do not express p53, we showed that activation by a mutant p53 was a direct enhancement. The mutant forms of p53 used in this study are found in various cancer cells. The activation of PCNA by mutant p53s may indicate a way to increase cell proliferation by the mutant p53s. Thus, our data indicate a possible functional role for the mutants of p53 found in cancer cells in activating several important loci, including PCNA.