Circulating Cell-Free DNA

Circulating cell-free DNA (cfDNA) refers to extracellular DNA present in body fluid that may be derived from both normal and diseased cells. The concentration, integrity, genetic, and epigenetic alternations in the cfDNA may suggest pathological conditions of the body, such as inflammation, autoimmune diseases, stress, or even malignancies. cfDNA from patients with malignancies contains variants as those in the tumor tissue cells, thus allowing noninvasive assessment of tumor in real time. The clinical detection of cfDNA is one major application of liquid biopsy and has great application value in the early diagnosis of clinical tumors, real-time progression monitoring, curative effect observation and evaluation, prognosis assessment, and metastasis risk analysis. This chapter summarizes the origin of cell-free DNA and its important clinical applications as a noninvasive biomarker

Protection of DNase in the shell of a pH-responsive, antibiotic-loaded micelle for biofilm targeting, dispersal and eradication

DNase can break down the extracellular matrix that keeps infectious bacterial biofilm together through cleavage of eDNA. Herewith, biofilm bacteria can become dispersed to assist antibiotic eradication but this has hitherto remained an in vitro possibility. In vivo DNase is rapidly broken down in blood, impeding blood-injection of DNase combined with antibiotics to cure bacterial infections. Herein, we report the synthesis of pH-responsive, self-targeting micelles self-assembled from a solution of poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) and poly(ε-caprolactone)-block-poly(amino ester) (PCL-b-PAE) with DNase conjugated to PAE-blocks. At physiological pH, this conjugation protected DNase inside the micellar shell, while PEG prevented adsorption of blood-borne proteins to the micelles. PAE became positively-charged below pH 6.4 facilitating self-targeting to an infectious biofilm. Simultaneously, PAE became hydrophilic and stretched to expose DNase upon accumulation in an infectious S. aureus biofilm where it degraded the biofilm matrix. PEG/PAE-DNase micelles internally core-loaded with ciprofloxacin significantly better eradicated murine pneumonia after blood-injection than ciprofloxacin-loaded PEG/PAE micelles without conjugated DNase or ciprofloxacin free in solution. Considering that DNase is clinically approved for use in cystic fibrosis patients, this paves the way for clinical translation of ciprofloxacin-loaded, PEG/PAE-DNase micelles for the treatment of pneumonia and other infections that can be reached through self-targeting after blood-injection

Micelle-like particles formed by carboxylic acid-terminated polystyrene and poly(4-vinyl pyridine) in chloroform/methanol mixed solution

Abstract Preparation and characterization of isolated particles and clusters of carboxylic acid-terminated polystyrene (CPS) and poly(4-vinyl pyridine) (P4VP) blends in chloroform/methanol (9/1, v/v) solution are reported. In chloroform CPS-P4VP blends form graft-like structure due to the interaction between terminal carboxylic acid and 4VP units. Upon addition of methanol, isolated particles and clusters with micelle-like structure were prepared. Dynamic light scattering (DLS) results and transmission electron microscopy (TEM) images both suggest the existence of isolated particles and clusters with micelle-like structure in the mixed solution. The effects of weight ratio of CPS to P4VP and addition of copper ion on the size of isolated particles and clusters were also investigated.

A Guanosine-Quadruplex Hydrogel as Cascade Reaction Container Consuming Endogenous Glucose for Infected Wound Treatment-A Study in Diabetic Mice

Diabetic foot ulcers infected with antibiotic‐resistant bacteria form a severe complication of diabetes. Antimicrobial‐loaded hydrogels are used as a dressing for infected wounds, but the ongoing rise in the number of antimicrobial‐resistant infections necessitates new, nonantibiotic based designs. Here, a guanosine‐quadruplex (G(4))‐hydrogel composed of guanosine, 2‐formylphenylboronic acid, and putrescine is designed and used as a cascade‐reaction container. The G(4)‐hydrogel is loaded with glucose‐oxidase and hemin. The first cascade‐reaction, initiated by glucose‐oxidase, transforms glucose and O(2) into gluconic acid and H(2)O(2). In vitro, this reaction is most influential on killing Staphylococcus aureus or Pseudomonas aeruginosa in suspension, but showed limited killing of bacteria in biofilm‐modes of growth. The second cascade‐reaction, however, transforming H(2)O(2) into reactive‐oxygen‐species (ROS), also enhances killing of biofilm bacteria due to hemin penetration into biofilms and interaction with eDNA G‐quadruplexes in the biofilm matrix. Therewith, the second cascade‐reaction generates ROS close to the target bacteria, facilitating killing despite the short life‐time of ROS. Healing of infected wounds in diabetic mice proceeds faster upon coverage by these G(4)‐hydrogels than by clinically common ciprofloxacin irrigation. Moreover, local glucose concentrations around infected wounds decrease. Concluding, a G(4)‐hydrogel loaded with glucose‐oxidase and hemin is a good candidate for infected wound dressings, particularly in diabetic patients

In-biofilm generation of nitric oxide using a magnetically-targetable cascade-reaction container for eradication of infectious biofilms

Cascade-reaction chemistry can generate reactive-oxygen-species that can be used for the eradication of infectious biofilms. However, suitable and sufficient oxygen sources are not always available near an infection site, while the reactive-oxygen-species generated are short-lived. Therefore, we developed a magnetic cascade-reaction container composed of mesoporous Fe3O4@SiO2 nanoparticles containing glucose-oxidase and t-arginine for generation of reactive-oxygen-species. Glucose-oxidase was conjugated with APTES facilitating coupling to Fe3O4@SiO2 nanoparticles and generation of H2O2 from glucose. L-arginine was loaded into the nanoparticles to generate NO from the H2O2 generated. Using an externally-applied magnetic field, cascade-reaction containers could be homogeneously distributed across the depth of an infectious biofilm. Cascade-reaction containers with coupled glucose-oxidase were effective in killing planktonic, Gram-positive and Gram-negative bacteria. Additional efficacy of the L-arginine based second cascade-reaction was only observed when H2O2 as well as NO were generated in-biofilm. In vivo accumulation of cascade-reaction containers inside abdominal Staphylococcus aureus biofilms upon magnetic targeting was observed real-time in living mice through an implanted, intra-vital window. Moreover, vancomycin-resistant, abdominal S. aureus biofilms could be eradicated consuming solely endogenous glucose, without any glucose addition. Herewith, a new, non-antibiotic-based infection-control strategy has been provided, constituting a welcome addendum to the shrinking clinical armamentarium to control antibiotic-resistant bacterial infections

Self-targeting, zwitterionic micellar dispersants enhance antibiotic killing of infectious biofilms:An intravital imaging study in mice

Extracellular polymeric substances (EPS) hold infectious biofilms together and limit antimicrobial penetration and clinical infection control. Here, we present zwitterionic micelles as a previously unexplored, synthetic self-targeting dispersant. First, a pH-responsive poly(ε-caprolactone)-block-poly(quaternary-amino-ester) was synthesized and self-assembled with poly(ethylene glycol)-block-poly(ε-caprolactone) to form zwitterionic, mixed-shell polymeric micelles (ZW-MSPMs). In the acidic environment of staphylococcal biofilms, ZW-MSPMs became positively charged because of conversion of the zwitterionic poly(quaternary-amino-ester) to a cationic lactone ring. This allowed ZW-MSPMs to self-target, penetrate, and accumulate in staphylococcal biofilms in vitro. In vivo biofilm targeting by ZW-MSPMs was confirmed for staphylococcal biofilms grown underneath an implanted abdominal imaging window through direct imaging in living mice. ZW-MSPMs interacted strongly with important EPS components such as eDNA and protein to disperse biofilm and enhance ciprofloxacin efficacy toward remaining biofilm, both in vitro and in vivo. Zwitterionic micellar dispersants may aid infection control and enhance efficacy of existing antibiotics against remaining biofilm

Coating of a Novel Antimicrobial Nanoparticle with a Macrophage Membrane for the Selective Entry into Infected Macrophages and Killing of Intracellular Staphylococci

Internalization of Staphylococcus aureus by macrophages can inactivate bacterial killing mechanisms, allowing intracellular residence and dissemination of infection. Concurrently, these staphylococci can evade antibiotics that are frequently unable to pass mammalian cell membranes. A binary, amphiphilic conjugate composed of triclosan and ciprofloxacin is synthesized that self-assemble through micelle formation into antimicrobial nanoparticles (ANPs). These novel ANPs are stabilized through encapsulation in macrophage membranes, providing membrane-encapsulated, antimicrobial-conjugated NPs (Me-ANPs) with similar protein activity, Toll-like receptor expression and negative surface charge as their precursor murine macrophage/human monocyte cell lines. The combination of Toll-like receptors and negative surface charge allows uptake of Me-ANPs by infected macrophages/monocytes through positively charged, lysozyme-rich membrane scars created during staphylococcal engulfment. Me-ANPs are not engulfed by more negatively charged sterile cells possessing less lysozyme at their surface. The Me-ANPs kill staphylococci internalized in macrophages in vitro. Me-ANPs likewise kill staphylococci more effectively than ANPs without membrane-encapsulation or clinically used ciprofloxacin in a mouse peritoneal infection model. Similarly, organ infections in mice created by dissemination of infected macrophages through circulation in the blood are better eradicated by Me-ANPs than by ciprofloxacin. These unique antimicrobial properties of macrophage-monocyte Me-ANPs provide a promising direction for human clinical application to combat persistent infections

Distribution Characteristics and Pollution Assessment of Soil Heavy Metals under Different Land-Use Types in Xuzhou City, China

Xuzhou, as a mining city in China, has been experiencing 130 years of coal mining and processing. To explore the spatial distribution characteristics and pollution status of soil heavy metals (Cr, Cd, As, Hg, Zn, and Pb) under different land-use types, a total of 2697 topsoil samples were collected in all of the areas (except for water) of Xuzhou in 2016. Overall, the mean concentrations of Cr (70.266 mg/kg), Cd (0.141 mg/kg), As (10.375 mg/kg), Hg (0.036 mg/kg), Zn (64.788 mg/kg), and Pb (24.84 mg/kg) in Xuzhou soils were lower than the environmental quality standard for soils (GB15618-1995). However, the mean concentrations of Cr, Hg, and Pb exceeded their corresponding background values, with the mean concentration of Hg being almost three times its background value. For different land-use types, the highest mean concentration of Cr was concentrated in grassland soils. The mean concentrations of Cd, As, Zn, and Pb in mining area soils were higher than those in the other soils. The mean concentration of Hg was the highest in the built-up area soils. Based on the potential ecological risk assessment, the forestland, garden land, grassland, and others were at low and moderate risk levels, the farmland and mining area were at low, moderate, and high risk levels, and the built-up area was at various risk levels in Xuzhou. There was a significant positive correlation between Cr, Pb, and Hg concentrations and the corresponding organic carbon contents in the farmland, built-up area, garden land, forestland, and other soils ( p < 0.01 ). A high degree of correlation was found between Cr and Hg concentrations, as well as organic carbon contents in grassland soils, with values of p < 0.05 and p < 0.01 , respectively. An obvious correlation could be seen between Hg concentrations and organic carbon contents in mining area soils ( p < 0.01 )

Polymer Communication A new approach to self-assembly of polymer blends in solution

Abstract A new approach to self-assembly of polymer blends in solution was studied by dynamic light scattering and transmission electron microscopy. Stable isolated particles and their clusters were obtained by dropping sulfonated polystyrene/THF solution into poly(4-vinyl pyridine)/methanol solution. The particles and clusters are stabilized by soluble poly(4-vinyl pyridine). The concentration of poly(4-vinyl pyridine) in methanol plays an important role in the self-assembly of polymer blends. Only in a suitable concentration range, stable particles can be prepared. Gelation appears at high poly(4-vinyl pyridine) concentration, while precipitation of sulfonated polystyrene occurs at low poly(4-vinyl pyridine) concentration.