Mesoscopic gelation of chitosan and genipin at below critical concentrations

2017 ◽  
Author(s):  
Christoph Engwer ◽  
Ronja Loy ◽  
Ioannis S. Chronakis ◽  
Ana C. Mendes ◽  
Francisco M. Goycoolea
Keyword(s):  
Sol Gel ◽  
Crosslinking Agent ◽  
Small Deformation ◽  
Macroscopic Appearance ◽  
Critical Concentrations ◽  
Gelation Kinetics ◽  
Gardenia Jasminoides ◽  
Sol Gel Transition ◽  
Low Cytotoxicity ◽  
High Concentrations

Genipin is increasingly used as a crosslinking agent for chitosans due to its low cytotoxicity as a naturally occurring extract of the plant <i>Gardenia jasminoides</i>. Genipin reacts with the primary amino groups of chitosan to form blue hydrogels. We studied the gelation kinetics of different chitosans varying in their properties (molar mass 34 000-213 000 g mol<sup>-1</sup>, degree of acetylation 9-20%) and genipin in detail. We found that critical sol-gel transition times obtained from dynamic light scattering were in good agreement with the results obtained by small deformation oscillatory rheometry and microviscosimetry at high concentrations of chitosan. However, at below critical concentrations, we found a second regime of gelation that followed the same Ross-Murphy's gelation kinetics. The macroscopic appearance of these samples was a suspension of weak gel-like particles that were sensitive to mechanical forces. We believe that the material is a mesoscopic gel, as described for other polymers. To the best of our knowledge, this is the first time that this phenomenon has been described for the gelling system of chitosan and genipin.

Mesoscopic gelation of chitosan and genipin at below critical concentrations

2017 ◽  
Author(s):  
Christoph Engwer ◽  
Ronja Loy ◽  
Ioannis S. Chronakis ◽  
Ana C. Mendes ◽  
Francisco M. Goycoolea
Keyword(s):  
Sol Gel ◽  
Crosslinking Agent ◽  
Small Deformation ◽  
Macroscopic Appearance ◽  
Critical Concentrations ◽  
Gelation Kinetics ◽  
Gardenia Jasminoides ◽  
Sol Gel Transition ◽  
Low Cytotoxicity ◽  
High Concentrations

Genipin is increasingly used as a crosslinking agent for chitosans due to its low cytotoxicity as a naturally occurring extract of the plant <i>Gardenia jasminoides</i>. Genipin reacts with the primary amino groups of chitosan to form blue hydrogels. We studied the gelation kinetics of different chitosans varying in their properties (molar mass 34 000-213 000 g mol<sup>-1</sup>, degree of acetylation 9-20%) and genipin in detail. We found that critical sol-gel transition times obtained from dynamic light scattering were in good agreement with the results obtained by small deformation oscillatory rheometry and microviscosimetry at high concentrations of chitosan. However, at below critical concentrations, we found a second regime of gelation that followed the same Ross-Murphy's gelation kinetics. The macroscopic appearance of these samples was a suspension of weak gel-like particles that were sensitive to mechanical forces. We believe that the material is a mesoscopic gel, as described for other polymers. To the best of our knowledge, this is the first time that this phenomenon has been described for the gelling system of chitosan and genipin.

Sol–gel transition of poly(3-hexylthiophene) revealed by capillary measurements: phase behaviors, gelation kinetics and the formation mechanism

Soft Matter ◽  
2012 ◽  
Vol 8 (3) ◽  
pp. 726-733 ◽  
Author(s):  
Wentao Xu ◽  
Haowei Tang ◽  
Hongying Lv ◽  
Jun Li ◽  
Xiaoli Zhao ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Sol Gel ◽  
Gelation Kinetics ◽  
Sol Gel Transition ◽  
Phase Behaviors ◽  
Gel Transition

Sol-gel transition in silica alkaline solutions. A NMR study

1994 ◽  
Vol 91 ◽  
pp. 901-908 ◽  
Author(s):  
H Zanni ◽  
P Nieto ◽  
L Fernandez ◽  
R Couty ◽  
P Barret ◽  
...  
Keyword(s):  
Sol Gel ◽  
Alkaline Solutions ◽  
Nmr Study ◽  
Sol Gel Transition ◽  
Gel Transition

PENGGUNAAN TiO2 PARTIKEL NANO HASIL SINTESIS BERBASIS AIR MENGGUNAKAN METODA SOL-GEL PADA BAHAN KAPAS SEBAGAI APLIKASI UNTUK TEKSTIL ANTI UV

Arena Tekstil ◽  
2013 ◽  
Vol 28 (1) ◽  
Author(s):  
Maya Komalasari ◽  
Bambang Sunendar
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sol Gel ◽  
Crosslinking Agent ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
X Ray ◽  
Infra Red ◽  
Scanning Electron

Partikel nano TiO2 berbasis air dengan pH basa telah berhasil disintesis dengan menggunakan metode sol-gel dan diimobilisasi pada kain kapas dengan menggunakan kitosan sebagai zat pengikat silang. Sintesis dilakukan  dengan prekursor TiCl4 pada konsentrasi 0,3 M, 0,5 M dan 1 M, dan menggunakan templat kanji dengan proses kalsinasi pada suhu 500˚C selama 2 jam. Partikel nano TiO2 diaplikasikan ke kain kapas dengan metoda pad-dry-cure dan menggunakan kitosan sebagai crosslinking agent. Berdasarkan hasil Scanning Electron Microscope (SEM),diketahui bahwa morfologi partikel TiO2 berbentuk spherical dengan ukuran nano (kurang dari 100 nm). Karakterisasi X-Ray Diffraction (XRD) menunjukkan adanya tiga tipe struktur kristal utama, yaitu (100), (101) dan (102) dengan fasa kristal yang terbentuk adalah anatase dan rutile. Pada karakterisasi menggunakan SEM terhadap serbuk dari TiO2 yang telah diaplikasikan ke permukaan kain kapas, terlihat adanya imobilisasi partikel nano TiO2 melalui ikatan hidrogen silang dengan kitosan pada kain kapas. Hasil analisa tersebut kemudian dikonfirmasi dengan FTIR (Fourier Transform Infra Red) yang hasilnya memperlihatkan puncak serapan pada bilangan gelombang 3495 cm-1, 2546 cm-1, dan 511 cm-1,  yang masing-masing diasumsikan sebagai adanya vibrasi gugus fungsi O-H, N-H dan Ti-O-Ti. Hasil SEM menunjukkan pula bahwa kristal nano yang terbentuk diantaranya adalah fasa rutile , yang berdasarkan literatur terbukti dapatberfungsi sebagai anti UV.

scholarly journals Synthesis of Nanogels: Current Trends and Future Outlook

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 36
Author(s):  
Emanuele Mauri ◽  
Sara Maria Giannitelli ◽  
Marcella Trombetta ◽  
Alberto Rainer
Keyword(s):  
3D Printing ◽  
Ad Hoc ◽  
Sol Gel ◽  
Controlled Polymerization ◽  
Current Trends ◽  
Chip Technology ◽  
Physico Chemical ◽  
Physical Interactions ◽  
Sol Gel Transition ◽  
Gel Transition

Nanogels represent an innovative platform for tunable drug release and targeted therapy in several biomedical applications, ranging from cancer to neurological disorders. The design of these nanocarriers is a pivotal topic investigated by the researchers over the years, with the aim to optimize the procedures and provide advanced nanomaterials. Chemical reactions, physical interactions and the developments of engineered devices are the three main areas explored to overcome the shortcomings of the traditional nanofabrication approaches. This review proposes a focus on the current techniques used in nanogel design, highlighting the upgrades in physico-chemical methodologies, microfluidics and 3D printing. Polymers and biomolecules can be combined to produce ad hoc nanonetworks according to the final curative aims, preserving the criteria of biocompatibility and biodegradability. Controlled polymerization, interfacial reactions, sol-gel transition, manipulation of the fluids at the nanoscale, lab-on-a-chip technology and 3D printing are the leading strategies to lean on in the next future and offer new solutions to the critical healthcare scenarios.

Analyzing the Effects of Silica Nanospheres on the Sol–Gel Transition Profile of Thermosensitive Hydrogels

Langmuir ◽  
2021 ◽  
Author(s):  
Lucas S. Ribeiro ◽  
Renata L. Sala ◽  
Leticia A. O. de Jesus ◽  
Sandra A. Cruz ◽  
Emerson R. Camargo
Keyword(s):  
Sol Gel ◽  
Silica Nanospheres ◽  
Thermosensitive Hydrogels ◽  
Sol Gel Transition ◽  
Gel Transition ◽  
Transition Profile

scholarly journals Gold Nanoparticles Synthesized Using Extracts of Cyclopia intermedia, Commonly Known as Honeybush, Amplify the Cytotoxic Effects of Doxorubicin

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 132
Author(s):  
Jumoke A. Aboyewa ◽  
Nicole R. S. Sibuyi ◽  
Mervin Meyer ◽  
Oluwafemi O. Oguntibeju
Keyword(s):  
Gold Nanoparticles ◽  
South African ◽  
Biological Activities ◽  
Mangifera Indica ◽  
Human Colon ◽  
Normal Breast ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Low Cytotoxicity ◽  
High Concentrations

Cyclopia intermedia (C. intermedia) is an indigenous South African shrub used to prepare the popular medicinal honeybush (HB) tea. This plant contains high levels of mangiferin (MGF), a xanthonoid that was reported to have numerous biological activities, including anti-tumor activity. MGF and extracts that contain high concentrations of MGF, such as extracts from Mangifera indica L. or mango have been used to synthesize gold nanoparticles (AuNPs) using green nanotechnology. It has previously been shown that when AuNPs synthesized from M. indica L. extracts are used in combination with doxorubicin (DOX) and Ayurvedic medicine, the anti-tumor effects appear to be augmented. It has also been demonstrated that MGF used in combination with DOX resulted in enhanced anti-tumor effects. In this study, C. intermedia (HB) and MGF were used to synthesize HB-AuNPs and MGF-AuNPs, respectively. The physicochemical properties of the AuNPs were characterized by the UV-Visible Spectroscopy (UV-Vis), dynamic light scattering (DLS), Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HR-TEM). The cytotoxicity of HB-AuNPs and MGF-AuNPs were assessed on human colon (Caco-2), prostate (PC-3) and glioblastoma (U87) cancer cells; as well as normal breast epithelial (MCF-12A) cells using the MTT assay. Both HB-AuNPs and MGF-AuNPs demonstrated relatively low cytotoxicity in these cells. However, when these nanoparticles were used in combination with DOX, the cytotoxicity of DOX was significantly augmented.

scholarly journals Photocrosslinking and photopatterning of magneto-optical nanocomposite sol–gel thin film under deep-UV irradiation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Bidaud ◽  
D. Berling ◽  
D. Jamon ◽  
E. Gamet ◽  
S. Neveu ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Optical Devices ◽  
High Concentration ◽  
Nanocomposite Thin Films ◽  
Deep Uv ◽  
High Concentrations ◽  
193 Nm ◽  
The Impact

AbstractThis paper is aimed at investigating the process of photocrosslinking under Deep-UV irradiation of nanocomposite thin films doped with cobalt ferrite magnetic nanoparticles (MNPs). This material is composed of a hybrid sol–gel matrix in which MNP can be introduced with high concentrations up to 20 vol%. Deep-UV (193 nm) is not only interesting for high-resolution patterning but we also show an efficient photopolymerization pathway even in the presence of high concentration of MNPs. In this study, we demonstrate that the photocrosslinking is based on the free radical polymerization of the methacrylate functions of the hybrid precursor. This process is initiated by Titanium-oxo clusters. The impact of the nanoparticles on the photopolymerization kinetic and photopatterning is investigated. We finally show that the photosensitive nanocomposite is suitable to obtain micropatterns with sub-micron resolution, with a simple and versatile process, which opens many opportunities for fabrication of miniaturized magneto-optical devices for photonic applications.

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