Enhanced Cellular Delivery of Tildipirosin by Xanthan Gum-Gelatin Composite Nanogels.

Tildipirosin has no significant inhibitory effect on intracellular bacteria because of its poor membrane permeability. To this end, tildipirosin-loaded xanthan gum-gelatin composite nanogels were innovatively prepared to improve the cellular uptake efficiency. The formation of the nanogels via interactions between the positively charged gelatin and the negatively charged xanthan gum was confirmed by powder X-ray diffraction and Fourier transform infrared. The results indicate that the optimal tildipirosin composite nanogels possessed a 3D network structure and were shaped like a uniformly dispersed ellipse, and the particle size, PDI, and ζ potential were 229.4 ± 1.5 nm, 0.26 ± 0.04, and -33.2 ± 2.2 mV, respectively. Interestingly, the nanogels exhibited gelatinase-responsive characteristics, robust cellular uptake via clathrin-mediated endocytosis, and excellent sustained release. With those pharmaceutical properties provided by xanthan gum-gelatin composite nanogels, the anti-Staphylococcus aureus activity of tildipirosin was remarkably amplified. Further, tildipirosin composite nanogels demonstrated good biocompatibility and low in vivo and in vitro toxicities. Therefore, we concluded that tildipirosin-loaded xanthan gum-gelatin composite nanogels might be employed as a potentially effective gelatinase-responsive drug delivery for intracellular bacterial infection.

Systemic dendrimer-drug nanomedicines for long-term treatment of mild-moderate cerebral palsy in a rabbit model.

BACKGROUND: Neuroinflammation mediated by microglia plays a central role in the pathogenesis of perinatal/neonatal brain injury, including cerebral palsy (CP). Therapeutics mitigating neuroinflammation potentially provide an effective strategy to slow the disease progression and rescue normal brain development. Building on our prior results which showed that a generation-4 hydroxyl poly(amidoamine) (PAMAM) dendrimer could deliver drugs specifically to activated glia from systemic circulation, we evaluated the sustained efficacy of a generation-6 (G6) hydroxyl-terminated PAMAM dendrimer that showed a longer blood circulation time and increased brain accumulation. N-acetyl-L-cysteine (NAC), an antioxidant and anti-inflammatory agent that has high plasma protein binding properties and poor brain penetration, was conjugated to G6-PAMAM dendrimer-NAC (G6D-NAC). The efficacy of microglia-targeted G6D-NAC conjugate was evaluated in a clinically relevant rabbit model of CP, with a mild/moderate CP phenotype to provide a longer survival of untreated CP kits, enabling the assessment of sustained efficacy over 15 days of life. METHODS: G6D-NAC was conjugated and characterized. Cytotoxicity and anti-inflammatory assays were performed in BV-2 microglial cells. The efficacy of G6D-NAC was evaluated in a rabbit model of CP. CP kits were randomly divided into 5 groups on postnatal day 1 (PND1) and received an intravenous injection of a single dose of PBS, or G6D-NAC (2 or 5 mg/kg), or NAC (2 or 5 mg/kg). Neurobehavioral tests, microglia morphology, and neuroinflammation were evaluated at postnatal day 5 (PND5) and day 15 (PND15). RESULTS: A single dose of systemic 'long circulating' G6D-NAC showed a significant penetration across the impaired blood-brain-barrier (BBB), delivered NAC specifically to activated microglia, and significantly reduced microglia-mediated neuroinflammation in both the cortex and cerebellum white matter areas. Moreover, G6D-NAC treatment significantly improved neonatal rabbit survival rate and rescued motor function to nearly healthy control levels at least up to 15 days after birth (PND15), while CP kits treated with free NAC died before PND9. CONCLUSIONS: Targeted delivery of therapeutics to activated microglia in neonatal brain injury can ameliorate pro-inflammatory microglial responses to injury, promote survival rate, and improve neurological outcomes that can be sustained for a long period. Appropriate manipulation of activated microglia enabled by G6D-NAC can impact the injury significantly beyond inflammation.

Cerebellar injury and impaired function in a rabbit model of maternal inflammation induced neonatal brain injury.

Cerebellum is involved in higher cognitive functions and plays important roles in neurological disorders. Cerebellar injury has been detected frequently in patients with preterm birth resulting in cognitive dysfunction later in life. Maternal infection and inflammation is associated with preterm birth and in neonatal brain injury. We have previously shown that intrauterine lipopolysaccharide (LPS) exposure induces white matter injury and microglial activation in the cerebral white matter tracts of neonatal rabbits, resulting in motor deficits consistent with the clinical findings of cerebral palsy (CP). Here we investigated whether intrauterine LPS exposure induced cerebellar inflammation and functional impairment. Timed-pregnant New Zealand white rabbits underwent a laparotomy on gestational day 28 (G28) and LPS (3200 EU, endotoxin group) was injected along the wall of the uterus as previously described. Controls did not receive surgical intervention. Kits born to control and endotoxin treated dams were euthanized on postnatal day (PND)1 (3 days post-injury) or PND5 (7 days post-injury) and cerebellum evaluated for presence of inflammation. The microglial morphology in cerebellar white matter areas was analyzed using Neurolucida and Neurolucida Explorer. mRNA expression of inflammatory cytokines was quantified by real-time-PCR. We found that intrauterine exposure to LPS induced intensive microglial activation in cerebellar white matter areas, as evidenced by increased numbers of activated microglia and morphological changes (amoeboid soma and retracted processes) that was accompanied by significant increases in pro-inflammatory cytokines. The Purkinje cell layer was less developed in endotoxin exposed kits than healthy controls. In kits that survived to PND 60, soma size and cell density of Purkinje cells were significantly decreased in endotoxin exposed kits compared to controls. The findings of altered Purkinje cell morphology were consistent with impaired cerebellar function as tested by eye-blink conditioning at 1 month of age. The results indicate that the cerebellum is vulnerable to perinatal insults and that therapies targeting cerebellar inflammation and injury may help in improving outcomes and function.

Maternal inflammation leads to impaired glutamate homeostasis and up-regulation of glutamate carboxypeptidase II in activated microglia in the fetal/newborn rabbit brain.

Astrocyte dysfunction and excessive activation of glutamatergic systems have been implicated in a number of neurologic disorders, including periventricular leukomalacia (PVL) and cerebral palsy (CP). However, the role of chorioamnionitis on glutamate homeostasis in the fetal and neonatal brains is not clearly understood. We have previously shown that intrauterine endotoxin administration results in intense microglial 'activation' and increased pro-inflammatory cytokines in the periventricular region (PVR) of the neonatal rabbit brain. In this study, we assessed the effect of maternal inflammation on key components of the glutamate pathway and its relationship to astrocyte and microglial activation in the fetal and neonatal New Zealand white rabbit brain. We found that intrauterine endotoxin exposure at gestational day 28 (G28) induced acute and prolonged glutamate elevation in the PVR of fetal (G29, 1day post-injury) and postnatal day 1 (PND1, 3days post-injury) brains along with prominent morphological changes in the astrocytes (soma hypertrophy and retracted processes) in the white matter tracts. There was a significant increase in glutaminase and N-Methyl-d-Aspartate receptor (NMDAR) NR2 subunit expression along with decreased glial L-glutamate transporter 1 (GLT-1) in the PVR at G29, that would promote acute dysregulation of glutamate homeostasis. This was accompanied with significantly decreased TGF-ß1 at PND1 in CP kits indicating ongoing neuroinflammation. We also show for the first time that glutamate carboxypeptidase II (GCPII) was significantly increased in the activated microglia at the periventricular white matter area in both G29 and PND1 CP kits. This was confirmed by in vitro studies demonstrating that LPS activated primary microglia markedly upregulate GCPII enzymatic activity. These results suggest that maternal intrauterine endotoxin exposure results in early onset and long-lasting dysregulation of glutamate homeostasis, which may be mediated by impaired astrocyte function and GCPII upregulation in activated microglia.

An unusual allosteric mobility of the C-terminal helix of a high-affinity alphaL integrin I domain variant bound to ICAM-5.

Integrins are cell surface receptors that transduce signals bidirectionally across the plasma membrane. The key event of integrin signaling is the allosteric regulation between its ligand-binding site and the C-terminal helix (alpha7) of integrin's inserted (I) domain. A significant axial movement of the alpha7 helix is associated with the open, active conformation of integrins. We describe the crystal structure of an engineered high-affinity I domain from the integrin alpha(L)beta(2) (LFA-1) alpha subunit in complex with the N-terminal two domains of ICAM-5, an adhesion molecule expressed in telencephalic neurons. The finding that the alpha7 helix swings out and inserts into a neighboring I domain in an upside-down orientation in the crystals implies an intrinsically unusual mobility of this helix. This remarkable feature allows the alpha7 helix to trigger integrin's large-scale conformational changes with little energy penalty. It serves as a mechanistic example of how a weakly bound adhesion molecule works in signaling.

N-terminal horseshoe conformation of DCC is functionally required for axon guidance and might be shared by other neural receptors.

Deleted in colorectal cancer (DCC) is a receptor for the axon guidance cues netrin-1 and draxin. The interactions between these guidance cues and DCC play a key role in the development of the nervous system. In the present study, we reveal the crystal structure of the N-terminal four Ig-like domains of DCC. The molecule folds into a horseshoe-like configuration. We demonstrate that this horseshoe conformation of DCC is required for guidance-cue-mediated axonal attraction. Structure-based mutations that disrupt the DCC horseshoe indeed impair its function. A comparison of the DCC horseshoe with previously described horseshoe structures has revealed striking conserved structural features and important sequence signatures. Using these signatures, a genome-wide search allows us to predict the N-terminal horseshoe arrangement in a number of other cell surface receptors, nearly all of which function in the nervous system. The N-terminal horseshoe appears to be evolutionally selected as a platform for neural receptors.

[Composition diversity and metabolic characters of lactic acid bacteria community SGL].

OBJECTIVE: We aimed to select a stable lactic acid bacteria community from switchgrass silage, that was efficient in lactic acid production. METHODS: We obtained the community by continuous restricted subcultivation in MRS broth, and analysed the composition diversity and stability of the community by 16S rRNA gene-based pyrosequencing and Denaturing Gradient Gel Electrophoresis (DGGE), respectively. In addition, we studied the effect of different nitrogen sources on growth and lactic acid production of the community, through adding different concentrations of yeast extraction, different nitrogen sources [yeast extract, peptone, urea and (NH4) 2SO4] and different proportions of (NH4)2SO4 and yeast extract leveled with elemental nitrogen 1.8 g/L. RESULTS: The microbial composition of SGL became stable from the 8th generation according to the results of DGGE. The pH value of the MRS inoculated with SGL dropped to 3.7, and the concentration of lactic acid reached 26 g/L after 24 h cultivation. The result of the pyrosequencing showed that the major composition of SGL were Lactobacillus nantensis (78.78%), Lactobacillus plantarum (7.92%), Lactobacillus pantheris (5.27%), Bacillus coagulans (4.41%) and Lactococcus lactics (3.31%). The best supplementation of yeast extraction for SGL was 20 g/L. When the elemental nitrogen ratio of (NH4) 2SO4 to yeast extract was 1:4, the growth and lactic acid production were no significant difference with 0:5 (P < 0.05). CONCLUSION: SGL had a great potential of application, as an efficient inoculant for ensilage or lactic acid production. This study would offer theoretical basis for cultivate and application of SGL in production.

[Effects of dioscorea modified pill on cognitive impairment of patients with VCIND: an preliminary study of proton magnetic resonance spectroscopy].

OBJECTIVE: To explore the therapeutic effect evaluation of proton magnetic resonance spectroscopy ((1)H-MRS) in patients with vascular cognitive impairment no dementia (VCIND) with dioscorea modified pill. METHODS: A total of 100 patients with VCIND were randomly assigned into the dioscorea modified pill group (n = 50) and the aricept group (n = 50). And 50 healthy volunteers were recruited as normal group. Each patient was examined with (1)H-MRS and scored with mini-mental state examination (MMSE) and clinical dementia rating (CDR) scale pre- and post-treatment. RESULTS: After therapy, the NAA/Cr ratios and the itemized scores of cognitive scale compared with that of pre-therapy had significantly difference (P < 0.05) in the dioscorea modified pill group (MMSE (26.5 ± 2.0), CDR(0.14 ± 0.23))vs(MMSE(25.1 ± 2.3), CDR(0.5)). But no difference existed in the aricept group (P > 0.05). CONCLUSION: (1)H-MRS may objectively reflect cognitive dysfunction in VCIND patients. And it has important values in the therapeutic effect evaluation of VCIND with dioscorea modified pill.

Basic concepts, recent advances, and future perspectives in the diagnosis of bovine mastitis.

Mastitis is one of the most widespread infectious diseases that adversely affects the profitability of the dairy industry worldwide. Accurate diagnosis and identification of pathogens early to cull infected animals and minimize the spread of infection in herds is critical for improving treatment effects and dairy farm welfare. The major pathogens causing mastitis and pathogenesis are assessed first. The most recent and advanced strategies for detecting mastitis, including genomics and proteomics approaches, are then evaluated . Finally, the advantages and disadvantages of each technique, potential research directions, and future perspectives are reported. This review provides a theoretical basis to help veterinarians select the most sensitive, specific, and cost-effective approach for detecting bovine mastitis early.

Metagenome-assembled genomes from enrichment cultures grown on xenobiotic solvents.

Microbes play a significant role in the cleanup of xenobiotic contaminants. Based on metagenomes derived from long-term enrichment cultures grown on xenobiotic solvents, we report 166 metagenome-assembled genomes, of which 137 are predicted to be more than 90% complete. These genomes broaden the representation of xenobiotic degraders.

Florfenicol core-shell composite nanogels as oral administration for efficient treatment of bacterial enteritis.

To reduce the bitterness of florfenicol, avoid its degradation by gastric acid, and enhance its antibacterial activity against Escherichia coli by targeting and slowly releasing drugs at the site of intestinal infection, with pectin as an anion carrier and chitosan oligosaccharides (COS) as a cationic carrier, florfenicol-loaded COS@pectin core nanogels were self-assembled by electrostatic interaction and then encapsulated in sodium carboxymethylcellulose (CMCNa) shell nanogels through the complexation of CMCNa and Ca2+ to prepare florfenicol core-shell composite nanogels in this study. The florfenicol core-shell composite nanogels were investigated for their formula choice, physicochemical characterization, pH-responsive performances, antibacterial activity, therapeutic efficacy, and in vitro and in vivo biosafety studies. The results indicated that the optimized formula was 0.6 g florfenicol, 0.79 g CMCNa, 0.30 g CaCl2, 0.05 g COS, and 0.10 g pectin, respectively. In addition, the mean particle diameter, polydispersity index, zeta potential, loading capacity, and encapsulation efficiency were 124.0 ± 7.2 nm, -22.9 ± 2.5 mV, 0.42 ± 0.03, 43.4 % ± 3.1 %, and 80.5 % ± 3.4 %, respectively. The appearance, lyophilized mass, resolvability, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and fourier transform infrared (FTIR) showed that the florfenicol core-shell composite nanogels were successfully prepared. Florfenicol core-shell composite nanogels had satisfactory stability, rheology, and pH-responsiveness, which were conducive to avoid degradation by gastric acid and achieve targeted and slow release at intestinal infection sites. More importantly, florfenicol core-shell composite nanogels had excellent antibacterial activity against Escherichia coli, a satisfactory therapeutic effect, and good palatability. In vitro and in vivo biosafety studies suggested the great promise of florfenicol core-shell composite nanogels. Therefore, the prepared florfenicol core-shell composite nanogels may be helpful for the treatment of bacterial enteritis as a biocompatible oral administration.

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels against Staphylococcus epidermidis.

BACKGROUND: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. OBJECTIVES: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. METHODS: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. RESULTS: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. CONCLUSIONS: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

Structural basis for RNA binding and homo-oligomer formation by influenza B virus nucleoprotein.

Influenza virus nucleoprotein (NP) is the major component of the viral ribonucleoprotein complex, which is crucial for the transcription and replication of the viral genome. We have determined the crystal structure of influenza B virus NP to a resolution of 3.2 Å. Influenza B NP contains a head, a body domain, and a tail loop. The electropositive groove between the head and body domains of influenza B NP is crucial for RNA binding. This groove also contains an extended flexible charged loop (amino acids [aa] 125 to 149), and two lysine clusters at the first half of this loop were shown to be crucial for binding RNA. Influenza B virus NP forms a crystallographic homotetramer by inserting the tail loop into the body domain of the neighboring NP molecule. A deeply buried salt bridge between R472 and E395 and a hydrophobic cluster at F468 are the major driving forces for the insertion. The analysis of the influenza B virus NP structure and function and comparisons with influenza A virus NP provide insights into the mechanisms of action and underpin efforts to design inhibitors for this class of proteins.

The RGD finger of Del-1 is a unique structural feature critical for integrin binding.

Developmental endothelial cell locus-1 (Del-1) glycoprotein is secreted by endothelial cells and a subset of macrophages. Del-1 plays a regulatory role in vascular remodeling and functions in innate immunity through interaction with integrin α(V)ß(3). Del-1 contains 3 epidermal growth factor (EGF)-like repeats and 2 discoidin-like domains. An Arg-Gly-Asp (RGD) motif in the second EGF domain (EGF2) mediates adhesion by endothelial cells and phagocytes. We report the crystal structure of its 3 EGF domains. The RGD motif of EGF2 forms a type II' ß turn at the tip of a long protruding loop, dubbed the RGD finger. Whereas EGF2 and EGF3 constitute a rigid rod via an interdomain calcium ion binding site, the long linker between EGF1 and EGF2 lends considerable flexibility to EGF1. Two unique O-linked glycans and 1 N-linked glycan locate to the opposite side of EGF2 from the RGD motif. These structural features favor integrin binding of the RGD finger. Mutagenesis data confirm the importance of having the RGD motif at the tip of the RGD finger. A database search for EGF domain sequences shows that this RGD finger is likely an evolutionary insertion and unique to the EGF domain of Del-1 and its homologue milk fat globule-EGF 8.

Structural basis of Dscam isoform specificity.

The Dscam gene gives rise to thousands of diverse cell surface receptors thought to provide homophilic and heterophilic recognition specificity for neuronal wiring and immune responses. Mutually exclusive splicing allows for the generation of sequence variability in three immunoglobulin ecto-domains, D2, D3 and D7. We report X-ray structures of the amino-terminal four immunoglobulin domains (D1-D4) of two distinct Dscam isoforms. The structures reveal a horseshoe configuration, with variable residues of D2 and D3 constituting two independent surface epitopes on either side of the receptor. Both isoforms engage in homo-dimerization coupling variable domain D2 with D2, and D3 with D3. These interactions involve symmetric, antiparallel pairing of identical peptide segments from epitope I that are unique to each isoform. Structure-guided mutagenesis and swapping of peptide segments confirm that epitope I, but not epitope II, confers homophilic binding specificity of full-length Dscam receptors. Phylogenetic analysis shows strong selection of matching peptide sequences only for epitope I. We propose that peptide complementarity of variable residues in epitope I of Dscam is essential for homophilic binding specificity.

Designing, Structural Determination, and Antibacterial Activity of Injectable Ciprofloxacin-loaded gelatin-sodium Carboxymethyl Cellulose composite Nanogels against Staphylococcus aureus.

BACKGROUND: The development of nanogels has become an attractive strategy to enhance the antibacterial activity performance of bacteria. METHODS: The ciprofloxacin composite nanogels were successfully prepared by electrostatic interaction between gelatin (positive charge) and CMC (negative charge) with the help of sodium tripolyphosphate (TPP) as ionic crosslinkers, to increase the antibacterial activity of ciprofloxacin against Staphylococcus aureus (S. aureus) mastitis infection. The formulation screening, characterization, in vitro release, antibacterial activity, and biosafety were studied. RESULTS: The optimized formulation was fabricated of 20 mg/mL (CMC) and 50mg/mL (gelatin). The optimized ciprofloxacin composite nanogels were homogenous canary yellow suspension with a sedimentation rate of 1 and were incorporated in nano-sized cross-linked polymeric networks. The particle sizes were distributed as, 402.7±1.3 nm, PDI of 0.12±0.01, ZP of -24.5±0.2mv, EE of 74.28%±0.03%, LC of 20.5%±0.05%. Scanning electron microscope images revealed that ciprofloxacin might be incorporated in nano-sized cross-linked polymeric networks. Fourier transform infrared showed that the spontaneous electrostatic interactions between CMC and gelatin produce the network structure and form the composite nanogels. Meanwhile, in vitro release study showed that ciprofloxacin composite nanogels had sustained-release performances. The ciprofloxacin composite nanogels had shown better antibacterial activity against SCV 102 isolate than S. aureus ATCC 29213 and S. aureus 101isolates. The biosafety studies suggested the great promise of the injectable ciprofloxacin composite nanogels as a biocompatible breast injection. CONCLUSION: This study will afford a potential approach for developing injectable ciprofloxacin-loaded gelatin-CMC composite nanogels for cow S. aureus mastitis therapy.

Clinical Value of Hospital-Community-Family Integrated Nursing Model in the Treatment of Patients with Hyperlipidemia Pancreatitis.

Objective: This study aimed to observe the impact of the hospital-community-family integrated nursing paradigm on the compliance, psychological state, and blood lipid levels in patients with hyperlipidemia pancreatitis (HLP). Methods: Totally 66 HLP patients treated in our institution between June 2018 and June 2021 were randomized to Exp group and Con group. The Exp group received the hospital-community-family integrated nursing mode, whereas Con group adopted conventional nursing. Outcome measures included patient compliance, mental state, and blood cholesterol levels. Results: Patients with integrated nursing exhibited markedly higher compliance than those with conventional nursing, as evinced by higher scores of compliance behavior, compliance awareness, medication attitude, and treatment attitude (P < 0.05). Integrated nursing offered more potent mitigation of negative emotions of patients than conventional nursing (P < 0.05). Integrated nursing resulted in better enhanced quality of life of patients versus conventional nursing (P < 0.05). Superior blood lipid amelioration was observed in patients after integration nursing versus those after conventional nursing, demonstrated by a higher serum high-density lipoprotein (HDL) level, and lower levels of triglycerides (TG), cholesterol (TC), and low-density lipoprotein (LDL) (P < 0.05). Patients were more satisfied with integrated nursing (96.97%) than conventional nursing (72.73%), suggesting a high patient acceptance of the nursing mode (P < 0.05). Conclusion: The hospital-community-family integrated nursing model provides a viable alternative to enhance HLP patients' compliance and optimize their psychological state and blood lipid levels, demonstrating good potential for clinical promotion.

On-demand release of enrofloxacin-loaded chitosan oligosaccharide-oxidized hyaluronic acid composite nanogels for infected wound healing.

In this study, enrofloxacin (ENR) was encapsulated by oxidized hyaluronic acid (OHA) containing aldehyde groups and chitosan oligosaccharide (COS) containing amino groups through Schiff's base reaction to achieve on-demand release in the micro-environment (pH 5.5 and HAase) of bacterial-infected wounds (Escherichia coli and Staphylococcus aureus). The formation mechanism, physicochemical characterization, responsive release performance, in vitro and in vivo antimicrobial activities, and in vivo regeneration in full-thickness wounds in a bacterial-infected mouse model of the ENR nanogels were systematically studied. According to the single-factor experiment and Design-Expert software, the optimized formula was 3.8 mg/ml COS, 0.5 mg/ml OHA, and 0.3 mg/ml ENR, respectively. The mean particle diameter, polydispersity index, zeta potential, loading capacity, and encapsulation efficiency were 35.6 ± 1.7 nm, -6.7 ± 0.5 mV, 0.25 ± 0.02, 30.4 % ± 1.3 %, and 76.3 % ± 2.6 %, respectively. The appearance, optical microscopy images, SEM, TEM, PXRD, and FTIR showed that the ENR nanogels were successfully prepared. The ENR nanogels exhibited obvious pH and HAase-responsiveness by swelling ratios and in vitro release and had stronger antibacterial activity with time-dependent and concentration-dependent effects, as well as accelerating infected wound healing. In vitro and in vivo biosafety studies suggested the great promise of ENR nanogels as biocompatible wound dressings for infected wounds.

Antibacterial activity of a novel glycyrrhizic acid-loaded chitosan composite nanogel in vitro against Staphylococcus aureus small colony variants.

Background This study aimed to improve the sustained and controlled release of glycyrrhizic acid to the infected site of Staphylococcus aureus small colony variants (SCVs). Methods The glycyrrhizic acid-loaded chitosan composite nanogel was prepared by inclusion action, Schiff's base formation, and electrostatic action. Furthermore, the formulation screening, characteristics, in vitro release, and antibacterial activity of the glycyrrhizic acid composite nanogel were explored. Results The final optimal formula comprised 10 mg/mL (chitosan) and 50 µL (glutaraldehyde). The loading capacity, encapsulation efficiency, mean size, polydispersity index, and zeta potential were 8.8%±1.6%, 92.1%±2.8%, 478.3±2.8 nm, 0.37±0.10, and 25.3±3.6 mv, respectively. Scanning electron microscope images showed a spherical shape with a relatively uniform distribution. The in vitro release study showed that glycyrrhizic acid composite nanogel exhibited a biphasic pattern with a sustained release of 52.1%±2.0% at 48 h in the pH 5.5 PBS. The minimum inhibitory and minimum biofilm inhibitory concentrations of glycyrrhizic acid composite nanogel against SCVs were 0.625 µg/mL. The time-killing curves and live/dead bacterial staining showed that glycyrrhizic acid composite nanogel had a stronger curative effect against SCVs strain with concentration-dependent. Conclusion This study provides promising glycyrrhizic acid composite nanogel to improve the treatment of SCV infection.

Guar gum modified tilmicosin-loaded sodium alginate/gelatin composite nanogels for effective therapy of porcine proliferative enteritis caused by Lawsonia intracellularis.

In order to overcome the treatment difficulty of Lawsonia intracellularis (L.intracellularis) using antibiotics, the tilmicosin (TIL)-loaded sodium alginate (SA)/gelatin composite nanogels modified with bioadhesive substances were designed. The optimized nanogels were prepared by electrostatic interaction between SA and gelatin at a mass ratio of 1:1 and CaCl2 as an ionic crosslinker and further modified with guar gum (GG). The optimized TIL-nanogels modified with GG had a uniform spherical shape with a diameter of 18.2 ± 0.3 nm, LC of 29.4 ± 0.2 %, EE of 70.4 ± 1.6 %, PDI of 0.30 ± 0.04, and ZP of -32.2 ± 0.5 mv. The FTIR, DSC, and PXRD showed that GG was covered on the surface of TIL-nanogels in a pattern of staggered arrangements. The TIL-nanogels modified with GG had the strongest adhesive strength amongst those with I-carrageenan and locust bean gum and the plain nanogels, and thus significantly enhanced the cellular uptake and accumulation of TIL via clathrin-mediated endocytosis. It exhibited an increased therapeutic effect against L.intracellularis in vitro and in vivo. This study will provide guidance for developing nanogels for intracellular bacterial infection treatment.