Targeted Release of Probiotics from Enteric Microparticulated Formulations

The development of advanced probiotic delivery systems, which preserve bacteria from degradation of the gastrointestinal tract and achieve a targeted release mediated by pH-independent swelling, is of great interest to improve the efficient delivery of probiotic bacteria to the target tissue. Gram-positive and Gram-negative bacteria models (Lactobacillus acidophilus (Moro) Hansen and Mocquot (ATCC® 4356™) and Escherichia coli S17, respectively) have been successfully encapsulated for the first time in pH-independent microparticulate polymethacrylates (i.e., Eudraguard biotic) used for the targeted delivery of nutraceuticals to the colon. These bacteria have also been encapsulated within the mucoadhesive polymethacrylate Eudragit RS 100 widely used as targeted release formulation for active pharmaceutical ingredients. The enteric microparticles remained unaltered under simulated gastric conditions and released the contained viable microbial cargo under simulated intestinal conditions. Buoyancies of 90.2% and 57.3% for Eudragit and Eudraguard microparticles, respectively, and long-term stability (5 months) for the encapsulated microorganisms were found. Cytotoxicity of the microparticles formulated with both polymers was evaluated (0.5–20 mg/mL) on Caco-2 cells, showing high cytocompatibility. These results underline the suitability of the synthesized materials for the successful delivery of probiotic formulations to the target organ, highlighting for the first time the potential use of Eudraguard biotic as an effective enteric coating for the targeted delivery of probiotics.

Download Full-text

Structure-Properties Correlation of Cross-Linked Penicillin G Acylase Crystals

Crystals ◽

10.3390/cryst11040451 ◽

2021 ◽

Vol 11 (4) ◽

pp. 451

Author(s):

Marta Kubiak ◽

Janine Mayer ◽

Ingo Kampen ◽

Carsten Schilde ◽

Rebekka Biedendieck

Keyword(s):

Mechanical Stability ◽

Structural Characteristics ◽

Penicillin G ◽

Bacillus Species ◽

Diffusion Limitations ◽

Small Water ◽

Long Term Stability ◽

Atomic Force ◽

First Time

In biocatalytic processes, the use of free enzymes is often limited due to the lack of long-term stability and reusability. To counteract this, enzymes can be crystallized and then immobilized, generating cross-linked enzyme crystals (CLECs). As mechanical stability and activity of CLECs are crucial, different penicillin G acylases (PGAs) from Gram-positive organisms have proven to be promising candidates for industrial production of new semisynthetic antibiotics, which can be crystallized and cross-linked to characterize the resulting CLECs regarding their mechanical and catalytic properties. The greatest hardness and Young’s modulus determined by indentation with an atomic force microscope were observed for CLECs of Bacillus species FJAT-PGA CLECs (26 MPa/1450 MPa), followed by BmPGA (Priestia megaterium PGA, 23 MPa/1170 MPa) and BtPGA CLECs (Bacillus thermotolerans PGA, 11 MPa/614 MPa). In addition, FJAT- and BtPGA CLECs showed up to 20-fold higher volumetric activities compared to BmPGA CLECs. Correlation to structural characteristics indicated that a high solvent content and low number of cross-linking residues might lead to reduced stability. Furthermore, activity seems to be restricted by small water channels due to severe diffusion limitations. To the best of our knowledge, we show for the first time in this study that the entire process chain for the characterization of diverse industrially relevant enzymes can be performed at the microliter scale to discover the most important relationships and limitations.

Download Full-text

Apoferritin/Vandetanib Association Is Long-Term Stable but Does Not Improve Pharmacological Properties of Vandetanib

International Journal of Molecular Sciences ◽

10.3390/ijms22084250 ◽

2021 ◽

Vol 22 (8) ◽

pp. 4250

Author(s):

Kateřina Jáklová ◽

Tereza Feglarová ◽

Simona Rex ◽

Zbyněk Heger ◽

Tomáš Eckschlager ◽

...

Keyword(s):

Cell Lines ◽

Targeted Delivery ◽

Medullary Thyroid Cancer ◽

Kinase Inhibitor ◽

Medullary Thyroid ◽

Long Term Stability ◽

Carcinoma Cell Lines ◽

Average Size ◽

Thyroid Carcinoma Cell

A tyrosine kinase inhibitor, vandetanib (Van), is an anticancer drug affecting the signaling of VEGFR, EGFR and RET protooncogenes. Van is primarily used for the treatment of advanced or metastatic medullary thyroid cancer; however, its usage is significantly limited by side effects, particularly cardiotoxicity. One approach to minimize them is the encapsulation or binding of Van in- or onto a suitable carrier, allowing targeted delivery to tumor tissue. Herein, we constructed a nanocarrier based on apoferritin associated with Van (ApoVan). Based on the characteristics obtained by analyzing the average size, the surface ζ-potential and the polydispersive index, ApoVan nanoparticles exhibit long-term stability and maintain their morphology. Experiments have shown that ApoVan complex is relatively stable during storage. It was found that Van is gradually released from its ApoVan form into the neutral environment (pH 7.4) as well as into the acidic environment (pH 6.5). The effect of free Van and ApoVan on neuroblastoma and medullary thyroid carcinoma cell lines revealed that both forms were toxic in both used cell lines, and minimal differences between ApoVan and Van were observed. Thus, we assume that Van might not be encapsulated into the cavity of apoferritin, but instead only binds to its surface.

Download Full-text

Scribing Method for Carbon Perovskite Solar Modules

Energies ◽

10.3390/en13071589 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1589 ◽

Cited By ~ 2

Author(s):

Simone M. P. Meroni ◽

Katherine E. A. Hooper ◽

Tom Dunlop ◽

Jenny A. Baker ◽

David Worsley ◽

...

Keyword(s):

Screen Printing ◽

Fill Factor ◽

Transparent Electrode ◽

Perovskite Solar Cell ◽

Metal Contacts ◽

Good Efficiency ◽

Long Term Stability ◽

First Time

The fully printable carbon triple-mesoscopic perovskite solar cell (C-PSC) has already demonstrated good efficiency and long-term stability, opening the possibility of lab-to-fab transition. Modules based on C-PSC architecture have been reported and, at present, are achieved through the accurate registration of each of the patterned layers using screen-printing. Modules based on this approach were reported with geometric fill factor (g-FF) as high as 70%. Another approach to create the interconnects, the so-called scribing method, was reported to achieve more than 90% g-FF for architectures based on evaporated metal contacts, i.e., without a carbon counter electrode. Here, for the first time, we adopt the scribing method to selectively remove materials within a C-PSC. This approach allowed a deep and selective scribe to open an aperture from the transparent electrode through all the layers, including the blocking layer, enabling a direct contact between the electrodes in the interconnects. In this work, a systematic study of the interconnection area between cells is discussed, showing the key role of the FTO/carbon contact. Furthermore, a module on 10 × 10 cm2 substrate with the optimised design showing efficiency over 10% is also demonstrated.

Download Full-text

Enhancement of efficiency and long-term stability in graphene/Si-quantum-dot heterojunction photodetectors by employing bis(trifluoromethanesulfonyl)-amide as a dopant for graphene

Journal of Materials Chemistry C ◽

10.1039/c7tc04647b ◽

2017 ◽

Vol 5 (48) ◽

pp. 12737-12743 ◽

Cited By ~ 14

Author(s):

Dong Hee Shin ◽

Chan Wook Jang ◽

Ju Hwan Kim ◽

Jong Min Kim ◽

Ha Seung Lee ◽

...

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Term Stability ◽

Long Term Stability ◽

Si Quantum Dot ◽

First Time ◽

Si Quantum Dots

Bis(trifluoromethanesulfonyl)-amide (TFSA) is for the first time employed as a dopant for graphene for graphene/Si-quantum-dots-based photodetectors.

Download Full-text

Optical Axis Perturbation Analysis for the Unit-Magnification Multipass System

Mathematical Problems in Engineering ◽

10.1155/2017/9528713 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11

Author(s):

Yin Guo ◽

Liqun Sun ◽

Zheng Yang

Keyword(s):

Optical Axis ◽

Optical Element ◽

Transfer Model ◽

Tolerance Range ◽

Long Term Stability ◽

Generalized Sensitivity ◽

Sensitivity Factors ◽

Element Transfer ◽

First Time

The optical axis sensitivity for the unit-magnification multipass system (UMS) is presented by using a general misaligned optical element transfer model. The generalized sensitivity factors SD1, SD2, ST1, and ST2 influenced by both the axial and angular misalignments of the objective mirrors in a UMS have been calculated for the first time. The Bernstein-Herzberg White Cells are used as an example, and their alignment tolerance and stability properties are found when their configurations change. The analysis in this paper is helpful for the design of other kinds of multipass gas cells (MGC) with high robustness and avoiding the violent vibration of the optical axis when the misalignment of each mirror is controlled within the tolerance range. Among the five possible perturbations sources, the misaligned factors δix,δiy,θix have more effects on the output beam’s position and the perturbed sources from δix,θix and δiy,θiy have more impacts on the output beam’s slope referred to as x-axis and y-axis, respectively. Higher reflection times mean smaller tolerance range. The results benefit the multipass cell design and the precise alignment of the mirrors within the cell with the purpose of long-term stability in measurements.

Download Full-text

Amphiphilic azopolymers capable to generate photo-sensitive micelles

Open Chemistry ◽

10.2478/s11532-011-0102-y ◽

2011 ◽

Vol 9 (6) ◽

pp. 1117-1125 ◽

Cited By ~ 4

Author(s):

Ioana Moleavin ◽

Constanta Ibanescu ◽

Anca Hodorog-Rusu ◽

Ecaterina Peptu ◽

Florica Doroftei ◽

...

Keyword(s):

Targeted Delivery ◽

Critical Concentration ◽

Fluorescence Emission ◽

Good Control ◽

Fluorescence Emission Spectrum ◽

Long Term Stability ◽

Micellar Aggregates ◽

Preliminary Study ◽

And Control

AbstractAmphiphilic macromolecular micelles are advantageous for drug delivery applications due to the decrease of side-effects, ease of screening drugs against degradation, long-term stability, targeted delivery and control of the amount of the released drug. A series of amphiphilic azo-polymers having a flexible or rigid main-chain were synthesized and characterized. The presence of chlorobenzyl side-groups allowed both the easy bonding of photo-sensitive or hydrophilic groups and good control of the degree of substitution. The chemical structure was confirmed by 1H-NMR. The critical concentration of aggregation (CCA) was calculated using the fluorescence emission spectrum of pyrene. The interest was focused on a preliminary study concerning the disaggregation capacity of micelles under UV irradiation. The presence of micellar aggregates was confirmed by DLS and SEM and different organization of the amphiphilic polymers was evidenced depending on polymers concentration and polymers structure. In low polymer concentrations in water predominantly globular aggregates were formed. The increase in concentration increased the polydispersity index due to the fusion of micelles and formation of associates of globular aggregates, inter-micellar associates (clusters) and vesicles.

Download Full-text

Extinction-resistant attention to long-term conditioned threat is indexed by selective visuocortical alpha suppression in humans

Scientific Reports ◽

10.1038/s41598-019-52315-1 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Christian Panitz ◽

Andreas Keil ◽

Erik M. Mueller

Keyword(s):

Visual Attention ◽

Time Windows ◽

Alpha Power ◽

Physiological Measures ◽

Time Frequency ◽

Long Term Stability ◽

Electrophysiological Studies ◽

First Time

Abstract Previous electrophysiological studies in humans have shown rapid modulations of visual attention after conditioned threat vs. safety cues (<500 ms post-stimulus), but it is unknown whether this attentional prioritization is sustained throughout later time windows and whether it is robust to extinction. To investigate sustained visual attention, we assessed visuocortical alpha suppression in response to conditioned and extinguished threat. We reanalysed data from N = 87 male participants that had shown successful long-term threat conditioning and extinction in self reports and physiological measures in a two-day conditioning paradigm. The current EEG time-frequency analyses on recall test data on Day 2 revealed that previously threat-conditioned vs. safety cues evoked stronger occipital alpha power suppression from 600 to 1200 ms. Notably, this suppression was resistant to previous extinction. The present study showed for the first time that threat conditioning enhances sustained modulation of visuocortical attention to threat in the long term. Long-term stability and extinction resistance of alpha suppression suggest a crucial role of visuocortical attention mechanisms in the maintenance of learned fears.

Download Full-text

Nanostructured SnS-N-doped graphene as an advanced electrocatalyst for the hydrogen evolution reaction

Chemical Communications ◽

10.1039/c5cc05644f ◽

2015 ◽

Vol 51 (86) ◽

pp. 15716-15719 ◽

Cited By ~ 54

Author(s):

S. S. Shinde ◽

Abdul Sami ◽

Dong-Hyung Kim ◽

Jung-Ho Lee

Keyword(s):

Hydrothermal Synthesis ◽

Hydrogen Evolution ◽

Hydrogen Evolution Reaction ◽

Term Stability ◽

Long Term Stability ◽

Highly Active ◽

Doped Graphene ◽

First Time

The scalable hydrothermal synthesis of the SnS/N-rGr hybrid is presented for the first time, which is used as a highly-active electrocatalyst with long-term stability in different media.

Download Full-text

Revision of the flightless click-beetle genus Neodima Schimmel & Platia (Elateridae: Dimini) endemic to China, with comments on its systematic position

Zootaxa ◽

10.11646/zootaxa.4604.1.2 ◽

2019 ◽

Vol 4604 (1) ◽

pp. 42

Author(s):

ROBIN KUNDRATA ◽

ELISKA SORMOVA ◽

LU QIU ◽

ALEXANDER S. PROSVIROV

Keyword(s):

Morphological Diversity ◽

Systematic Position ◽

Biodiversity Hotspots ◽

Diagnostic Characters ◽

Term Stability ◽

Mountainous Regions ◽

Long Term Stability ◽

Click Beetle ◽

First Time

Distribution of flightless insect lineages often help us to identify the areas of long-term stability which serve as biodiversity hotspots. In this paper we taxonomically revise the wingless click-beetle genus Neodima Schimmel & Platia, 1992 endemic to the mountainous regions of Sichuan, China. Neodima sichuanensis Schimmel & Platia, 1992 and N. cechovskyi Schimmel, 1998 are redescribed, and N. belousovi Prosvirov & Kundrata sp. nov. is described as new for science. The distribution and morphological diversity of Neodima is discussed, main diagnostic characters for all species are figured, and an identification key to the species of this genus is provided. Mouthparts as well as female pregenital segments and genitalia are described and figured for the first time for this genus. Further, we compare Neodima to morphologically similar genera, and discuss its systematic position within Dimini.

Download Full-text

Fabrication and characterization of hierarchical multipod silver citrate complex microcrystals with excellent SERS properties

RSC Advances ◽

10.1039/c6ra00221h ◽

2016 ◽

Vol 6 (15) ◽

pp. 12311-12314 ◽

Cited By ~ 9

Author(s):

Yongyun Mao ◽

Yuwen Yang ◽

Hongwei Yang ◽

Jiao Han ◽

Yiming Zeng ◽

...

Keyword(s):

Aqueous Solution ◽

Sers Substrate ◽

Excellent Performance ◽

Term Stability ◽

Long Term Stability ◽

Citrate Complex ◽

Fabrication And Characterization ◽

First Time

Novel hierarchical multipods silver citrate complexes (SCC) microcrystals have been successfully synthesized in aqueous solution for the first time. The multipods SCC microcrystals showed excellent performance and long-term-stability as SERS substrate.

Download Full-text