Prediction of Disease Progression of COVID-19 Based upon Machine Learning.

BACKGROUND: Since December 2019, COVID-19 has spread throughout the world. Clinical outcomes of COVID-19 patients vary among infected individuals. Therefore, it is vital to identify patients at high risk of disease progression. METHODS: In this retrospective, multicenter cohort study, COVID-19 patients from Huoshenshan Hospital and Taikang Tongji Hospital (Wuhan, China) were included. Clinical features showing significant differences between the severe and nonsevere groups were screened out by univariate analysis. Then, these features were used to generate classifier models to predict whether a COVID-19 case would be severe or nonsevere based on machine learning. Two test sets of data from the two hospitals were gathered to evaluate the predictive performance of the models. RESULTS: A total of 455 patients were included, and 21 features showing significant differences between the severe and nonsevere groups were selected for the training and validation set. The optimal subset, with eleven features in the k-nearest neighbor model, obtained the highest area under the curve (AUC) value among the four models in the validation set. D-dimer, CRP, and age were the three most important features in the optimal-feature subsets. The highest AUC value was obtained using a support vector-machine model for a test set from Huoshenshan Hospital. Software for predicting disease progression based on machine learning was developed. CONCLUSION: The predictive models were successfully established based on machine learning, and achieved satisfactory predictive performance of disease progression with optimal-feature subsets.

Preparation of [Amine-Terminated Generation 5 Poly(amidoamine)]-graft-Poly(lactic-co-glycolic acid) Electrospun Nanofibrous Mats for Scaffold-Mediated Gene Transfection.

Combining biomaterial scaffolds with gene cargos for gene therapy is promising for tissue engineering. Herein, we developed a gene delivery platform through surface grafting of amine-terminated generation 5 poly(amidoamine) (PAMAM) dendrimers (G5·NH2) with biodegradable electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers by combining layer-by-layer (LbL) electrostatic assembly technology with dendrimer chemistry. PLGA nanofibers were precoated with positively charged poly(diallydimethylammoium chloride) and poly(acrylic acid) through electrostatic interaction and then subsequently cross-linked with G5·NH2 dendrimer covalently through 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride chemistry. The successful grafting of G5·NH2 dendrimer on PLGA nanofibers was confirmed by X-ray photoelectron spectroscopy. Scanning electron microscopy studies show that smooth, uniform morphology of nanofibers does not significantly change after grafting of G5·NH2 dendrimers except for a slight increase in the fiber diameter, whereas atomic force microscopy images at a high-resolution scale indicated a slightly rough surface for PLGA nanofibers after grafting with G5·NH2 dendrimer. Additionally, PLGA nanofibrous scaffolds became hydrophilic after grafting with G5·NH2 dendrimers. Biological investigation showed that the developed G5·NH2-g-PLGA nanofibrous scaffolds not only allowed for the attachment and proliferation of NIH 3T3 cells but also were capable of complexing pDNA and delivering pDNA/dendrimer complex for solid state gene transfection in situ. The functionalization of PLGA nanofibers with dendrimers may find diverse applications in the area of tissue engineering, gene therapy, and drug delivery.

Rheological and controlled release properties of hydrogels based on mushroom hyperbranched polysaccharide and xanthan gum.

A hyperbranched polysaccharide, coded as TM3a, was extracted from the Pleurotus tuber-regium sclerotia. TM3a was hybridized with xanthan gum (XG) by chemical crosslinking using sodium trimetaphosphate (STMP) to obtain new hydrogels with self-healing and release-controlled properties. The oscillatory rheological measurements indicated that chemically crosslinking was happened immediately on mixing STMP solutions into the XG-TM3a solutions, and the crosslinked network developed slightly as time increased. The resultant hydroges were disturbed into the loose structures and regrouped the microstructure in 2 min when a large and a small amplitude oscillation were applied in turn, suggesting a self-healable property. The XG-TM3a-STMP hydrogels exhibited shear-thinning behavior with yield stress. The storage modulus of the XG5-TM3a-STMP hydrogel was 445.2 Pa at 1% strain and 243.3 Pa at 100% strain, and yield stress was 160.6 Pa, which was higher than the corresponding value of the XG5-STMP hydrogel. The morphological observation indicated the aggregates of double helical XG chains exhibited directional arrangement, and were combined with the TM3a aggregates to constitute a network of hierarchical structures. The hybrid hydrogels with enhanced mechanical properties displayed good drug loading efficiencies and sustained drug release properties.

Layer-by-Layer Assembly of Polyelectrolyte Multilayer onto PET Fabric for Highly Tunable Dyeing with Water Soluble Dyestuffs.

Poly(ethyleneterephthalate) (PET) is a multi-purpose and widely used synthetic polymer in many industrial fields because of its remarkable advantages such as low cost, light weight, high toughness and resistance to chemicals, and high abrasion resistance. However, PET suffers from poor dyeability due to its non-polar nature, benzene ring structure as well as high crystallinity. In this study, PET fabrics were firstly treated with an alkaline solution to produce carboxylic acid functional groups on the surface of the PET fabric, and then was modified by polyelectrolyte polymer through the electrostatic layer-by-layer self-assembly technology. The polyelectrolyte multilayer-deposited PET fabric was characterized using scanning electron microscopy SEM, contact angle, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The dyeability of PET fabrics before and after surface modification was systematically investigated. It showed that the dye-uptake of the polyelectrolyte multilayer-deposited PET fabric has been enhanced compared to that of the pristine PET fabric. In addition, its dyeability is strongly dependent on the surface property of the polyelectrolyte multilayer-deposited PET fabric and the properties of dyestuffs.

Fine tuning of the pH-sensitivity of laponite-doxorubicin nanohybrids by polyelectrolyte multilayer coating.

Despite the wide research done in the field, the development of advanced drug delivery systems with improved drug delivery properties and effective anticancer capability still remains a great challenge. Based on previous work that showed the potentialities of the nanoclay Laponite as a pH-sensitive doxorubicin (Dox) delivery vehicle, herein we report a simple method to modulate its extent of drug release at different pH values. This was achieved by alternate deposition of cationic poly(allylamine) hydrochloride and anionic poly(sodium styrene sulfonate) (PAH/PSS) polyelectrolytes over the surface of Dox-loaded Laponite nanoparticles using the electrostatic layer-by-layer (LbL) self-assembly approach. The successful formation of polyelectrolyte multilayer-coated Dox/Laponite systems was confirmed by Dynamic Light Scattering and zeta potential measurements. Systematic studies were performed to evaluate their drug release profiles and anticancer efficiency. Our results showed that the presence of the polyelectrolyte multilayers improved the sustained release properties of Laponite and allowed a fine tuning of the extension of drug release at neutral and acidic pH values. The cytotoxicity presented by polyelectrolyte multilayer-coated Dox/Laponite systems towards MCF-7 cells was in accordance with the drug delivery profiles. Furthermore, cellular uptake studies revealed that polyelectrolyte multilayer-coated Dox/Laponite nanoparticles can be effectively internalized by cells conducting to Dox accumulation in cell nucleus.

PAMAM Dendrimer/pDNA Functionalized-Magnetic Iron Oxide Nanoparticles for Gene Delivery.

Herein, we report an easy and ingenious method to functionalize magnetic iron oxide nanoparticles (MNPs) with plasmid DNA (pDNA) to obtain nanohybrid systems suitable for nucleic acid therapy. The nanohybrids were prepared by combining complexes of dendrimers and pDNA (dendriplexes) and poly(styrene) sulfonate-coated MNPs through electrostatic interactions. The effects of the dendrimer generation (generations 2, 4 and 6) and the amine to phosphate group (N/P) ratio on the hydrodynamic diameter, zeta potential, cell viability, cellular internalization and transfection efficiency of the nanohybrids were systematically investigated at different transfection conditions (including incubation time, pDNA concentration, presence or absence of an external magnetic field, and presence or absence of fetal bovine serum). The results confirmed that the nanohybrids were able to transfect NIH 3T3 cells, and that the level of gene expression (the luciferase protein reporter gene was used) was strongly dependent on the dendrimer generation, the N/P ratio, and the pDNA concentration. The best system was based on dendriplex-coated MNPs formed by generation 6 dendrimers at an N/P ratio of 10 that, at optimized conditions, led to a gene expression level which was not significantly different from that obtained only using dendriplexes. In summary, a coherent set of results was reached indicating the potential of the developed nanohybrids as effective gene delivery nanomaterials.

Dendrimer-assisted formation of fluorescent nanogels for drug delivery and intracellular imaging.

Although, in general, nanogels present a good biocompatibility and are able to mimic biological tissues, their unstability and uncontrollable release properties still limit their biomedical applications. In this study, a simple approach was used to develop dual-cross-linked dendrimer/alginate nanogels (AG/G5), using CaCl2 as cross-linker and amine-terminated generation 5 dendrimer (G5) as a cocrosslinker, through an emulsion method. Via their strong electrostatic interactions with anionic AG, together with cross-linker Ca(2+), G5 dendrimers can be used to mediate the formation of more compact structural nanogels with smaller size (433 ± 17 nm) than that (873 ± 116 nm) of the Ca(2+)-cross-linked AG nanogels in the absence of G5. Under physiological (pH 7.4) and acidic (pH 5.5) conditions, the sizes of Ca(2+)-cross-linked AG nanogels gradually decrease probably because of their degradation, while dual-cross-linked AG/G5 nanogels maintain a relatively more stable structure. Furthermore, the AG/G5 nanogels effectively encapsulate the anticancer drug doxorubicin (Dox) with a loading capacity 3 times higher than that of AG nanogels. The AG/G5 nanogels were able to release Dox in a sustained way, avoiding the burst release observed for AG nanogels. In vitro studies show that the AG/G5-Dox NGs were effectively taken up by CAL-72 cells (a human osteosarcoma cell line) and maintain the anticancer cytotoxicity levels of free Dox. Interestingly, G5 labeled with a fluorescent marker can be integrated into the nanogels and be used to track the nanogels inside cells by fluorescence microscopy. These findings demonstrate that AG/G5 nanogels may serve as a general platform for therapeutic delivery and/or cell imaging.

Redox-responsive alginate nanogels with enhanced anticancer cytotoxicity.

Although doxorubicin (Dox) has been widely used in the treatment of different types of cancer, its insufficient cellular uptake and intracellular release is still a limitation. Herein, we report an easy process for the preparation of redox-sensitive nanogels that were shown to be highly efficient in the intracellular delivery of Dox. The nanogels (AG/Cys) were obtained through in situ cross-linking of alginate (AG) using cystamine (Cys) as a cross-linker via a miniemulsion method. Dox was loaded into the AG/Cys nanogels by simply mixing it in aqueous solution with the nanogels, that is, by the establishment of electrostatic interactions between the anionic AG and the cationic Dox. The results demonstrated that the AG/Cys nanogels are cytocompatible, have a high drug encapsulation efficiency (95.2 ± 4.7%), show an in vitro accelerated release of Dox in conditions that mimic the intracellular reductive conditions, and can quickly be taken up by CAL-72 cells (an osteosarcoma cell line), resulting in higher Dox intracellular accumulation and a remarkable cell death extension when compared with free Dox. The developed nanogels can be used as a tool to overcome the problem of Dox resistance in anticancer treatments and possibly be used for the delivery of other cationic drugs in applications beyond cancer.

QSPR studies of impact sensitivity of nitro energetic compounds using three-dimensional descriptors.

The quantitative structure-property relationship (QSPR) studies were performed between molecular structures and impact sensitivity for a diverse set of nitro energetic compounds based on three-dimensional (3D) descriptors. The entire set of 156 compounds was divided into a training set of 127 compounds and a test set of 29 compounds according to Kennard and Stones algorithm. Multiple linear regression (MLR) analysis was employed to select the best subset of descriptors and to build linear models; while nonlinear models were developed by means of artificial neural network (ANN). The obtained models with ten descriptors involved show good predictive power for the test set: a squared correlation coefficient (R²) of 0.7222 and a standard error of estimation (s) of 0.177 were achieved by the MLR model; while by the ANN model, R² and s were 0.8658 and 0.130, respectively. Therefore, the proposed models can be used to predict the impact sensitivity of new nitro compounds for engineering.

Manipulation of the loading and size of zero-valent iron nanoparticles immobilized in electrospun polymer nanofibers.

A simple approach to controlling the loading percentage and size of zero-valent iron nanoparticles (ZVI NPs) immobilized within polyacrylic acid (PAA)/polyvinyl alcohol (PVA) nanofibrous mats for dye remediation applications is described. A functional "nanoreactor" comprised by electrospun PAA/PVA nanofibers served to bind ferric ions with the carboxyl groups of PAA, prior to their reduction to ZVI NPs. The resulting ZVI NP-immobilized hybrid polymer nanofibers were characterized using scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The morphology of the polymer nanofibers exhibited no appreciable change even after eight cycles of ferric ion binding/reduction, and the loading percentage and size of the ZVI NPs were controlled simply by varying the number of ferric ion binding/reduction cycles. Dye remediation experiments revealed that the decoloration effect of ZVI NPs immobilized within the polymer nanofibers is both size- and loading percentage-dependent. At low loading percentages, smaller ZVI NPs better decoloration efficiency, while at relatively higher loading percentages the permeability of the nanofibers plays an important role in determining ZVI NPs decoloration efficiency. The strategy of controlling loading percentages and sizes of the ZVI NPs within polymer nanofibers may be extendable to other particle systems for various applications in catalysis, sensing, and environmental remediation.

Influence of dendrimer surface charge on the bioactivity of 2-methoxyestradiol complexed with dendrimers.

We report the complexation of a potential anticancer agent 2-methoxyestradiol (2-ME) with generation 5 (G5) poly(amidoamine) dendrimers having different surface functional groups for therapeutic applications. The complexation experiment shows that approximately 6-8 drug molecules can be complexed with one dendrimer molecule regardless the type of the dendrimer terminal groups. The bioactivity of 2-ME complexed with dendrimers was found to be significantly dependent on the surface charge of G5 dendrimers. In vitro cell biological assays show that amine, hydroxyl, and acetamide-terminated G5 dendrimers with positive, slightly positive, and close to neutral surface charges, respectively are able to deliver 2-ME to inhibit cancer cell growth. In contrast, 2-ME complexed with carboxyl-terminated G5 dendrimers with negative surface charges does not show its inherent bioactivity. Further molecular dynamics simulation studies show that the compact structure of carboxylated G5 dendrimers complexed with 2-ME does not allow the release of the drug molecules even at a pH of 5.0, which is the typical pH value in lysosome. Our findings indicate that the surface modification of dendrimers with different charges is crucial for the development of formulations of various anticancer drugs for therapeutic applications.

Polyelectrolyte multilayer-assisted immobilization of zero-valent iron nanoparticles onto polymer nanofibers for potential environmental applications.

We report a facile approach to synthesizing and immobilizing zero-valent iron nanoparticles (ZVI NPs) onto polyelectrolyte (PE) multilayer-assembled electrospun polymer nanofibers for potential environmental applications. In this approach, negatively charged cellulose acetate (CA) nanofibers fabricated by electrospinning were assembled with multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and polyacrylic acid (PAA) through electrostatic layer-by-layer assembly. The formed PAA/PDADMAC multilayers onto CA nanofibers were then used as a nanoreactor to complex Fe(II) ions through the binding with the free carboxyl groups of PAA for subsequent reductive formation of ZVI NPs. Combined scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetry analysis studies demonstrate that the ZVI NPs are successfully synthesized and uniformly distributed into the PE multilayers assembled onto the CA nanofibers. The produced hybrid nanofibrous mats containing ZVI NPs were found to exhibit superior capability to decolorize acid fuchsin, an organic dye in dyeing wastewater. We show that the loading capacity of ZVI NPs can be tuned by changing the number of PE layers and the cycles of binding/reduction process. Increasing the number of the binding/reduction cycles leads to a slight bigger size of the ZVI NPs, which is not beneficial for improving the reactivity of ZVI NPs. The present approach to synthesizing and immobilizing ZVI NPs onto polymer nanofibers opens a new avenue to fabricating various fiber-based composite materials with a high surface area to volume ratio for environmental, catalytic, and sensing applications.