Sparsely PEGylated poly(beta-amino ester) polyplexes enhance antigen specific T-cell response of a bivalent SARS-CoV-2 DNA vaccine.

DNA technology has emerged as a promising route to accelerated manufacture of sequence agnostic vaccines. For activity, DNA vaccines must be protected and delivered to the correct antigen presenting cells. However, the physicochemical properties of the vector must be carefully tuned to enhance interaction with immune cells and generate sufficient immune response for disease protection. In this study, we have engineered a range of polymer-based nanocarriers based on the poly(beta-amino ester) (PBAE) polycation platform to investigate the role that surface poly(ethylene glycol) (PEG) density has on pDNA encapsulation, formulation properties and gene transfectability both in vitro and in vivo. We achieved this by synthesising a non-PEGylated and PEGylated PBAE and produced formulations containing these PBAEs, and mixed polyplexes to tune surface PEG density. All polymers and co-formulations produced small polyplex nanoparticles with almost complete encapsulation of the cargo in all cases. Despite high gene transfection in HEK293T cells, only the fully PEGylated and mixed formulations displayed significantly higher expression of the reporter gene than the negative control in dendritic cells. Further in vivo studies with a bivalent SARS-CoV-2 pDNA vaccine revealed that only the mixed formulation led to strong antigen specific T-cell responses, however this did not translate into the presence of serum antibodies indicating the need for further studies into improving immunisation with polymer delivery systems.

An international survey of contemporary practices towards fertility assessment and preservation in patients undergoing radical inguinal orchidectomy for testicular cancer.

Objective: The study aims to assess current international clinician attitudes, practices and barriers towards fertility assessment and preservation in patients undergoing radical inguinal orchidectomy (RIO) for testicular cancer. Materials and methods: An international online survey of urologists and urologists in training who perform RIO for testicular cancer was developed by the British Association of Urological Surgeons (BAUS) Sections of Andrology and Oncology and the British Urology Researchers in Surgical Training (BURST). The recruitment process used social media and the emailing lists of national urological societies. Responses were collected between 10/02/2021 and 31/05/2021 and stored using password-protected Research Electronic Data Capture (REDCap) database software. The primary outcome was the proportion of urologists who routinely offer semen cryopreservation prior to RIO. The study was reported according to the Checklist for Reporting Results of Internet E-Surveys platform. Results: A total of 393 respondents took part in the online survey; of these, the majority were from the United Kingdom (65.9%), with the remaining international respondents (34.1%) from six different continents, which included 45 different countries. Of the respondents, 57.1% reported that they would routinely offer semen cryopreservation to all patients undergoing RIO for testicular cancer. In addition, 36.0% of urologists routinely performed pre-operative semen analysis, and 22.1% routinely performed pre-operative testicular serum hormone profile. Of the respondents, 14.4% performed expedited RIO within 48 h; 31.2% of respondents reported that they considered no delay to RIO to allow for semen cryopreservation to be acceptable. Conclusions: A significant proportion of international urologists do not offer pre-operative fertility assessment and preservation in men undergoing RIO for testicular cancer. Surgery is performed in an expedited fashion within 1 week in the majority of patients. Urologists perceive there to be a lack of access and availability to fertility services, and that delay to RIO to allow for fertility preservation is often not acceptable.

Triblock copolymer micelles enhance solubility, permeability and activity of a quorum sensing inhibitor against Pseudomonas aeruginosa biofilms.

Antimicrobial resistance is a threat to public health for which new treatments are urgently required. The capability of bacteria to form biofilms is of particular concern as it enables high bacterial tolerance to conventional therapies by reducing drug diffusion through the dense, exopolymeric biofilm matrix and the upregulation of antimicrobial resistance machinery. Quorum sensing (QS), a process where bacteria use diffusible chemical signals to coordinate group behaviour, has been shown to be closely interconnected with biofilm formation and bacterial virulence in many top priority pathogens including Pseudomonas aeruginosa. Inhibition of QS pathways therefore pose an attractive target for new therapeutics. We have recently reported a new series of pqs quorum sensing inhibitors (QSIs) that serve as potentiators for antibiotics in P. aeruginosa infections. The impact on biofilms of some reported QSIs was however hindered by their poor penetration through the bacterial biofilm, limiting the potential for clinical translation. In this study we developed a series of poly(ß-amino ester) (PBAE) triblock copolymers and evaluated their ability to form micelles, encapsulate a QSI and enhance subsequent delivery to P. aeruginosa biofilms. We observed that the QSI could be released from polymer micelles, perturbing the pqs pathway in planktonic P. aeruginosa. In addition, one of the prepared polymer variants increased the QSIs efficacy, leading to an enhanced potentiation of ciprofloxacin (CIP) action and therefore improved reduction in biofilm viability, compared to the non-encapsulated QSI. Thus, we demonstrate QSI encapsulation in polymeric particles can enhance its efficacy through improved biofilm penetration.

Free drug and ROS-responsive nanoparticle delivery of synergistic doxorubicin and olaparib combinations to triple negative breast cancer models.

Combinations of the topoisomerase II inhibitor doxorubicin and the poly (ADP-ribose) polymerase inhibitor olaparib offer potential drug-drug synergy for the treatment of triple negative breast cancers (TNBC). In this study we performed in vitro screening of combinations of these drugs, administered directly or encapsulated within polymer nanoparticles, in both 2D and in 3D spheroid models of breast cancer. A variety of assays were used to evaluate drug potency, and calculations of combination index (CI) values indicated that synergistic effects of drug combinations occurred in a molar-ratio dependent manner. It is suggested that the mechanisms of synergy were related to enhancement of DNA damage as shown by the level of double-strand DNA breaks, and mechanisms of antagonism associated with mitochondrial mediated cell survival, as indicated by reactive oxygen species (ROS) generation. Enhanced drug delivery and potency was observed with nanoparticle formulations, with a greater extent of doxorubicin localised to cell nuclei as evidenced by microscopy, and higher cytotoxicity at the same time points compared to free drugs. Together, the work presented identifies specific combinations of doxorubicin and olaparib which were most effective in a panel of TNBC cell lines, explores the mechanisms by which these combined agents might act, and shows that formulation of these drug combinations into polymeric nanoparticles at specific ratios conserves synergistic action and enhanced potency in vitro compared to the free drugs.

Charge neutralized poly(ß-amino ester) polyplex nanoparticles for delivery of self-amplifying RNA.

Therapeutic self-amplifying RNA (saRNA) is a promising approach for disease treatment, as it can be administered in lower doses than messenger RNA (mRNA) to achieve comparable protein production levels. However, saRNA requires an appropriate delivery vehicle to protect it during transit and facilitate its transfection. A widely-adopted approach has been to use polycations to condense these large anionic macromolecules into polyplex nanoparticles, however their high charge density often elicits cytotoxic effects. In this study we postulated that we could improve the potency and tolerability of such delivery vehicles by co-formulating poly(ß-amino ester)s saRNA polyplexes with a non-toxic anionic polymer, γ-polyglutamic acid (γ-PGA) to neutralize partially this positive charge. Accordingly, we prepared a poly(ß-amino ester) from 1,6-hexanedioldiacrylate (HDDA) and 4-aminobutanol (ABOL) and initially evaluated the physicochemical properties of the binary polyplexes (i.e. formed from polymer and saRNA only). Optimised binary polyplex formulations were then taken forward for preparation of ternary complexes containing pHDDA-ABOL, saRNA and γ-PGA. Our findings demonstrate that γ-PGA integration into polyplexes significantly enhanced transfection efficacy in HEK293T and A431 cells without affecting polyplex size. Notably, γ-PGA incorporation leads to a pronounced reduction in zeta potential, which reduced the toxicity of the ternary complexes in moDC, NIH3T3, and A431 cells. Furthermore, the presence of γ-PGA contributed to colloidal stability, reducing aggregation of the ternary complexes, as evidenced by insignificant changes in polydispersity index (PDI) after freeze-thaw cycles. Overall, these results suggest that incorporating the appropriate ratio of a polyanion such as γ-PGA with polycations in RNA delivery formulations is a promising way to improve the in vitro delivery of saRNA.

Ciprofloxacin Poly(ß-amino ester) Conjugates Enhance Antibiofilm Activity and Slow the Development of Resistance.

To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial biofilms are a particular concern in this context as they are responsible for over 80% of bacterial infections and are inherently more recalcitrant toward antimicrobial treatments. The high tolerance of biofilms to conventional antibiotics has been attributed to several factors, including reduced drug diffusion through the dense exopolymeric matrix and the upregulation of antimicrobial resistance machinery with successful biofilm eradication requiring prolonged high doses of multidrug treatments. A promising approach to tackle bacterial infections involves the use of polymer drug conjugates, shown to improve upon free drug toxicity and bioavailability, enhance drug penetration through the thick biofilm matrix, and evade common resistance mechanisms. In the following study, we conjugated the antibiotic ciprofloxacin (CIP) to a small library of biodegradable and biocompatible poly(ß-amino ester) (PBAE) polymers with varying central amine functionality. The suitability of the polymers as antibiotic conjugates was then verified in a series of assays including testing of efficacy and resistance response in planktonic Gram-positive and Gram-negative bacteria and the reduction of viability in mono- and multispecies biofilm models. The most active polymer within the prepared PBAE-CIP library was shown to achieve an over 2-fold increase in the reduction of biofilm viability in a Pseudomonas aeruginosa monospecies biofilm and superior elimination of all the species present within the multispecies biofilm model. Hence, we demonstrate that CIP conjugation to PBAEs can be employed to achieve improved antibiotic efficacy against clinically relevant biofilm models.

Synthetic macromolecular peptide-mimetics with amino acid substructure residues as protein stabilising excipients.

The clinical use of protein and peptide biotherapeutics requires fabrication of stable products. This particularly concerns stability towards aggregation of proteins or peptides. Here, we tested a hypothesis that interactions between a synthetic peptide, which is an aggregation-prone region analogue, and its homologous sequence on a protein of interest, could be exploited to design excipients which stabilise the protein against aggregation. A peptide containing the analogue of lysozyme aggregation-prone region (GILQINSRW) was conjugated to a RAFT agent and used to initiate the polymerisation of N-hydroxyethyl acrylamide, generating a GILQINSRW-HEA90 polymer, which profoundly reduced lysozyme aggregation. Substitution of tryptophan in GILQINSRW with glycine, to form GILQINSRG, revealed that tryptophan is a critical amino acid in the protein stabilisation by GILQINSRW-HEA90. Accordingly, polymeric peptide-mimetics of tryptophan, phenylalanine and isoleucine, which are often present in aggregation-prone regions, were synthesized. These were based on synthetic oligomers of acrylamide derivatives of indole-3 acetic acid (IND), phenylacetic acid (PHEN), or 2-methyl butyric acid (MBA), respectively, conjugated with hydrophilic poly(N-hydroxyethyl acrylamide) blocks to form amphiphilic copolymers denoted as INDm-, PHENm- and MTBm-b-HEAn. These materials were tested as protein stabilisers and it was shown that solution properties and the abilities of these materials to stabilise insulin and the peptide IDR 1018 towards aggregation are dependent on the chemical nature of their side groups. These data suggest a structure-activity relationship, whereby the indole-based INDm-b-HEAn peptide-mimetic displays properties of a potential stabilising excipient for protein formulations.

Chain-extension in hyperbranched polymers alters tissue distribution and cytotoxicity profiles in orthotopic models of triple negative breast cancers.

The therapeutic efficacy of nanomedicines is highly dependent on their access to target sites in the body, and this in turn is markedly affected by their size, shape and transport properties in tissue. Although there have been many studies in this area, the ability to design nanomaterials with optimal physicochemical properties for in vivo efficacy remains a significant challenge. In particular, it is often difficult to quantify the detailed effects of cancer drug delivery systems in vivo as tumour volume reduction, a commonly reported marker of efficacy, does not always correlate with cytotoxicity in tumour tissue. Here, we studied the behaviour in vivo of two specific poly(2-hydroxypropyl methacrylamide) (pHPMA) pro-drugs, with hyperbranched and chain-extended branched architectures, redox-responsive backbone components, and pH-sensitive linkers to the anti-cancer drug doxorubicin. Evaluation of the biodistribution of these polymers following systemic injection indicated differences in the circulation time and organ distribution of the two polymers, despite their very similar hydrodynamic radii (∼10 and 15 nm) and architectures. In addition, both polymers showed improved tumour accumulation in orthotopic triple-negative breast cancers in mice, and decreased accumulation in healthy tissue, as compared to free doxorubicin, even though neither polymer-doxorubicin pro-drug decreased overall tumour volume as much as the free drug under the dosing regimens selected. However, the results of histopathological examinations by haematoxylin and eosin, and TUNEL staining indicated a higher population of apoptotic cells in the tumours for both polymer pro-drug treatments, and in turn a lower population of apoptotic cells in the heart, liver and spleen, as compared to free doxorubicin treatment. These data suggest that the penetration of these polymer pro-drugs was enhanced in tumour tissue relative to free doxorubicin, and that the combination of size, architecture, bioresponsive backbone and drug linker degradation yielded greater efficacy for the polymers as measured by biomarkers than that of tumour volume. We suggest therefore that the effects of nanomedicines may be different at various length scales relative to small molecule free drugs, and that penetration into tumour tissue for some nanomedicines may not be as problematic as prior reports have suggested. Furthermore, the data indicate that dual-responsive crosslinked polymer-prodrugs in this study may be effective nanomedicines for breast cancer chemotherapy, and that endpoints beyond tumour volume reduction can be valuable in selecting candidates for pre-clinical trials.

Reading minds or reading scripts? De-intellectualising theory of mind.

Understanding the origins of human social cognition is a central challenge in contemporary science. In recent decades, the idea of a 'Theory of Mind' (ToM) has emerged as the most popular way of explaining unique features of human social cognition. This default view has been progressively undermined by research on 'implicit' ToM, which suggests that relevant precursor abilities may already be present in preverbal human infants and great apes. However, this area of research suffers from conceptual difficulties and empirical limitations, including explanatory circularity, over-intellectualisation, and inconsistent empirical replication. Our article breaks new ground by adapting 'script theory' for application to both linguistic and non-linguistic agents. It thereby provides a new theoretical framework able to resolve the aforementioned issues, generate novel predictions, and provide a plausible account of how individuals make sense of the behaviour of others. Script theory is based on the premise that pre-verbal infants and great apes are capable of basic forms of agency-detection and non-mentalistic goal understanding, allowing individuals to form event-schemata that are then used to make sense of the behaviour of others. We show how script theory circumvents fundamental problems created by ToM-based frameworks, explains patterns of inconsistent replication, and offers important novel predictions regarding how humans and other animals understand and predict the behaviour of others.

Probing expression of E-selectin using CRISPR-Cas9-mediated tagging with HiBiT in human endothelial cells.

E-selectin is expressed on endothelial cells in response to inflammatory cytokines and mediates leukocyte rolling and extravasation. However, studies have been hampered by lack of experimental approaches to monitor expression in real time in living cells. Here, NanoLuc Binary Technology (NanoBiT) in conjunction with CRISPR-Cas9 genome editing was used to tag endogenous E-selectin in human umbilical vein endothelial cells (HUVECs) with the 11 amino acid nanoluciferase fragment HiBiT. Addition of the membrane-impermeable complementary fragment LgBiT allowed detection of cell surface expression. This allowed the effect of inflammatory mediators on E-selectin expression to be monitored in real time in living endothelial cells. NanoBiT combined with CRISPR-Cas9 gene editing allows sensitive monitoring of real-time changes in cell surface expression of E-selectin and offers a powerful tool for future drug discovery efforts aimed at this important inflammatory protein.

MicroRNA-based therapeutics for inflammatory disorders of the microbiota-gut-brain axis.

An emerging but less explored shared pathophysiology across microbiota-gut-brain axis disorders is aberrant miRNA expression, which may represent novel therapeutic targets. miRNAs are small, endogenous non-coding RNAs that are important transcriptional repressors of gene expression. Most importantly, they regulate the integrity of the intestinal epithelial and blood-brain barriers and serve as an important communication channel between the gut microbiome and the host. A well-defined understanding of the mode of action, therapeutic strategies and delivery mechanisms of miRNAs is pivotal in translating the clinical applications of miRNA-based therapeutics. Accumulating evidence links disorders of the microbiota-gut-brain axis with a compromised gut-blood-brain-barrier, causing gut contents such as immune cells and microbiota to enter the bloodstream leading to low-grade systemic inflammation. This has the potential to affect all organs, including the brain, causing central inflammation and the development of neurodegenerative and neuropsychiatric diseases. In this review, we have examined in detail miRNA biogenesis, strategies for therapeutic application, delivery mechanisms, as well as their pathophysiology and clinical applications in inflammatory gut-brain disorders. The research data in this review was drawn from the following databases: PubMed, Google Scholar, and Clinicaltrials.gov. With increasing evidence of the pathophysiological importance for miRNAs in microbiota-gut-brain axis disorders, therapeutic targeting of cross-regulated miRNAs in these disorders displays potentially transformative and translational potential. Further preclinical research and human clinical trials are required to further advance this area of research.

OptoRheo: Simultaneous in situ micro-mechanical sensing and imaging of live 3D biological systems.

Biomechanical cues from the extracellular matrix (ECM) are essential for directing many cellular processes, from normal development and repair, to disease progression. To better understand cell-matrix interactions, we have developed a new instrument named 'OptoRheo' that combines light sheet fluorescence microscopy with particle tracking microrheology. OptoRheo lets us image cells in 3D as they proliferate over several days while simultaneously sensing the mechanical properties of the surrounding extracellular and pericellular matrix at a sub-cellular length scale. OptoRheo can be used in two operational modalities (with and without an optical trap) to extend the dynamic range of microrheology measurements. We corroborated this by characterising the ECM surrounding live breast cancer cells in two distinct culture systems, cell clusters in 3D hydrogels and spheroids in suspension culture. This cutting-edge instrument will transform the exploration of drug transport through complex cell culture matrices and optimise the design of the next-generation of disease models.

Precise and systematic end group chemistry modifications on PAMAM and poly(l-lysine) dendrimers to improve cytosolic delivery of mRNA.

Here, we aimed to chemically modify PAMAM dendrimers using lysine as a site-selective anchor for successfully delivering mRNA while maintaining a low toxicity profile. PAMAM dendrimers were multi-functionalised by amidation reactions in a regioselective, quantitative and stepwise manner with carefully selected property-modifying surface groups. Alternatively, novel lysine-based dendrimers were prepared in the same manner with the aim to unlock their potential in gene delivery. The modified dendrimers were then formulated with Cy5-EGFP mRNA by bulk mixing via liquid handling robotics across different nitrogen to phosphate ratios. The resulting dendriplexes were characterised by size, charge, mRNA encapsulation, and mRNA binding affinity. Finally, their in-vitro delivery activity was systematically investigated across key cellular trafficking stages to relate chemical design to cellular effect. We demonstrate our findings in different cell lines and benchmarked relative to a commercially available transfection agent, jetPEI®. We demonstrate that specific surface modifications are required to generate small, reliable and well-encapsulated positively charged dendriplex complexes. Furthermore, we show that introduction of fusogenic groups is essential for driving endosomal escape and achieving cellular delivery and translation of mRNA in these cell lines.

Design of Quorum Sensing Inhibitor-Polymer Conjugates to Penetrate Pseudomonas aeruginosa Biofilms.

Antimicrobial resistance (AMR) is a global threat to public health with a forecast of a negative financial impact of one trillion dollars per annum, hence novel therapeutics are urgently needed. The resistance of many bacteria against current drugs is further augmented by the ability of these microbes to form biofilms where cells are encased in a slimy extracellular matrix and either adhered to a surface or forming cell aggregates. Biofilms form physiochemical barriers against the penetration of treatments such as small molecule antibacterials, rendering most treatments ineffective. Pseudomonas aeruginosa, a priority pathogen of immediate concern, controls biofilm formation through multiple layers of gene regulation pathways including quorum sensing (QS), a cell-to-cell signaling system. We have recently reported a series of inhibitors of the PqsR QS regulator from this organism that can potentiate the action of antibiotics. However, these QS inhibitors (QSIs) have shown modest effects on biofilms in contrast with planktonic cultures due to poor penetration through the biofilm matrix. To enhance the delivery of the inhibitors, a small library of polymers was designed as carriers of a specific QSI, with variations in the side chains to introduce either positively charged or neutral moieties to aid penetration into and through the P. aeruginosa biofilm. The synthesized polymers were evaluated in a series of assays to establish their effects on the inhibition of the Pqs QS system in P. aeruginosa, the levels of inhibitor release from polymers, and their impact on biofilm formation. A selected cationic polymer-QSI conjugate was found to penetrate effectively through biofilm layers and to release the QSI. When used in combination with ciprofloxacin, it enhanced the biofilm antimicrobial activity of this antibiotic compared to free QSI and ciprofloxacin under the same conditions.

Hybrid Poly(ß-amino ester) Triblock Copolymers Utilizing a RAFT Polymerization Grafting-From Methodology.

The biocompatibility, biodegradability, and responsiveness of poly(ß-amino esters) (PBAEs) has led to their widespread use as biomaterials for drug and gene delivery. Nonetheless, the step-growth polymerization mechanism that yields PBAEs limits the scope for their structural optimization toward specific applications because of limited monomer choice and end-group modifications. Moreover, to date the post-synthetic functionalization of PBAEs has relied on grafting-to approaches, challenged by the need for efficient polymer-polymer coupling and potentially difficult post-conjugation purification. Here a novel grafting-from approach to grow reversible addition-fragmentation chain transfer (RAFT) polymers from a PBAE scaffold is described. This is achieved through PBAE conversion into a macromolecular chain transfer agent through a multistep capping procedure, followed by RAFT polymerization with a range of monomers to produce PBAE-RAFT hybrid triblock copolymers. Following successful synthesis, the potential biological applications of these ABA triblock copolymers are illustrated through assembly into polymeric micelles and encapsulation of a model hydrophobic drug, followed by successful nanoparticle (NP) uptake in breast cancer cells. The findings demonstrate this novel synthetic methodology can expand the scope of PBAEs as biomaterials.

Improving bone health in prostate cancer patients starting androgen deprivation therapy: does Fracture Risk Assessment Tool (FRAX®) enhance stratification and targeted management?

Androgen deprivation therapy for prostate cancer can lead to osteoporosis and increased fracture risk. The Fracture Risk Assessment Tool (FRAX®) questionnaire can be used for risk stratification, and our study has demonstrated that the majority of men (91%) in our cohort commencing ADT for prostate cancer were considered low risk for future osteoporotic fracture. PURPOSE/INTRODUCTION: Long-term use of androgen deprivation therapy (ADT) in prostate cancer patients results in increased bone turnover and decreased bone mineral density (BMD). Proper assessment of any existing osteoporotic fracture risk is crucial prior to starting treatment. However, this risk assessment is poorly performed in these patients in spite of available validated tools including the Fracture Risk Assessment Tool (FRAX®). The objective of this study was to assess the distribution of osteoporotic fracture risk in a cohort of men commencing ADT for prostate cancer using the FRAX® algorithm. METHODS: Between July 2020 and May 2022, 200 men filled in the FRAX® questionnaire just before ADT. They were stratified into the high-risk (> 20% probability of a MOF over the next 10 years), intermediate-, and low-risk categories for fragility fractures. We also measured their serum vitamin D and calcium levels. RESULTS: The average age was 73.5 years (54-89). It took less than 10 min to complete the assessment. Only six patients were at high-risk, were started on bisphosphonates immediately, and referred for a dual energy X-ray absorptiometry (DEXA) scan. Twelve patients in the intermediate-risk category were referred for DEXA scans for bone mineral density measurements. A total of 182 patients (91%), were in the low-risk category and given lifestyle advice only. All had normal calcium levels but 134 (67%) patients, mostly in the low-risk category, had reduced vitamin D levels (< 50 nmol/L). CONCLUSION: The FRAX® questionnaire is simple and immediately identifies patients who are at risk of fragility fractures. Our study has demonstrated that the majority of men (91%) in our cohort commencing ADT for prostate cancer were considered low risk for future osteoporotic fracture. We were surprised that more than half of our patients had low vitamin D levels.

Evaluation of the relative potential for contact and doffing transmission of SARS-CoV-2 by a range of personal protective equipment materials.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-the causative agent of coronavirus disease 2019 (COVID-19)-has caused a global public health emergency. Personal protective equipment (PPE) is the primary defence against viral exposure in healthcare and community settings. However, the surfaces of PPE materials may trap virus for contact transmission or through laden aerosols generated during removal of PPE, through cleaning or during movement. In this study, the relative efficacy of current PPE materials in terms of virion adsorption to materials and their antiviral potency, has been evaluated on a wide range of PPE for the first time, including four polymer glove types, two types of scrubs, apron material, a mask, visor and a selection of other commercial polymers and products. Although differences in virion adsorption to the test materials were observed, none of the existing polymer-based PPE resulted in more than tenfold reduction in the SARS-CoV-2 titre within either 10 min or 30 min contact period. The wettability and surface chemistry of the test materials were analysed to investigate any correlations with their surface physicochemical properties. While no correlation was found between wettability and viral retention under air flow challenge, one secondary ion of m/z 101.03 (+) and three secondary ions of m/z 31.98 (-), 196.93 (-) and 394.33 (+) in ToF-SIMS data of the test materials showed positive and negative correlations with the viral retention, respectively, which was identified by PLS regression model, suggesting that the surface chemistry plays a role in determining the extent of virion adsorption. Our findings outline the material aspects that influence the efficacy of current PPE against SARS-CoV-2 transmission and give suggestions on the development of novel simple polymer-based PPE for better infection protection.

Metabolic Signatures of Surface-Modified Poly(lactic-co-glycolic acid) Nanoparticles in Differentiated THP-1 Cells Derived with Liquid Chromatography-Mass Spectrometry-based Metabolomics.

Polymeric nanoparticles (NPs) are widely used in preclinical drug delivery investigations, and some formulations are now in the clinic. However, the detailed effects of many NPs at the subcellular level have not been fully investigated. In this study, we used differentiated THP-1 macrophage cells, as a model, to investigate the metabolic changes associated with the use of poly (lactic-co-glycolic acid) (PLGA) NPs with different surface coating or conjugation chemistries. Liquid chromatography-mass spectrometry-based metabolic profiling was performed on the extracts (n = 6) of the differentiated THP-1 cells treated with plain, Pluronic (F-127, F-68, and P-85)-coated and PEG-PLGA NPs and control (no treatment). Principal component analysis and orthogonal partial least squares-discriminant analysis (OPLS-DA) in conjunction with univariate and pathway analyses were performed to identify significantly changed metabolites and pathways related to exposure of the cells to NPs. OPLS-DA of each class in the study compared to the control showed clear separation and clustering with cross-validation values of R 2 and Q 2 > 0.5. A total of 105 metabolites and lipids were found to be significantly altered in the differentiated THP-1 cell profiles due to the NP exposure, whereas more than 20 metabolic pathways were found to be affected. These pathways included glycerophospholipid, sphingolipid, linoleic acid, arginine and proline, and alpha-linolenic acid metabolisms. PLGA NPs were found to perturb some amino acid metabolic pathways and altered membrane lipids to a different degree. The metabolic effect of the PLGA NPs on the cells were comparable to those caused by silver oxide NPs and other inorganic nanomaterials. However, PEG-PLGA NPs demonstrated a reduced impact on the cellular metabolism compared to Pluronic copolymer-coated PLGA and plain PLGA NPs.