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Cesnik S, Perrotta A, Cian A, Tormen M, Bergmann A, Coclite AM. Humidity Responsive Reflection Grating Made by Ultrafast Nanoimprinting of a Hydrogel Thin Film. Macromol Rapid Commun 2022; 43:e2200150. [PMID: 35770908 DOI: 10.1002/marc.202200150] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/01/2022] [Indexed: 11/11/2022]
Abstract
The response time of state of the art humidity sensors is approximately 8 s. A faster tracking of humidity change is especially required for health care devices. We focused our research on the direct nanostructuring of a humidity-sensitive polymer thin film and combined it with an optical read-out method. Our goal was to improve the response time by changing the surface-to-volume ratio of the thin film and to test a different measurement method compared to state of the art sensors. Large and homogeneous nanostructured areas were fabricated by nanoimprint lithography on poly(2-hydroxyethyl methacrylate) thin films. Those thin films were made by initiated chemical vapor deposition (iCVD). To the author's knowledge, this is the first time nanoimprint lithography was applied on iCVD polymer thin films. With the imprinting process we developed a diffraction grating in the visible wavelength regime. The optical and physicochemical behavior of the nanostructures was modeled with multi-physic simulations. After successful modeling and fabrication a first proof of concept showed that humidity dependency by using an optical detection of the first diffraction order peak is observable. The response time of the structured thin film resulted to be at least three times faster compared to commercial sensors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Alberto Perrotta
- Italian National Research Council-Institute of Nanotechnology (CNR-NANOTEC), via Orabona 4, Bari, 70126, Italy
| | - Alessandro Cian
- Center for Materials and Microsystems, Fondazione Bruno Kessler, FBK, Via Sommarive 18, Trento, I-38123, Italy
| | - Massimo Tormen
- ThunderNIL S.r.l., Area Science Park, Trieste (TS), Italy
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Solid Dispersions Incorporated into PVP Films for the Controlled Release of Trans-Resveratrol: Development, Physicochemical and In Vitro Characterizations and In Vivo Cutaneous Anti-Inflammatory Evaluation. Pharmaceutics 2022; 14:pharmaceutics14061149. [PMID: 35745722 PMCID: PMC9230924 DOI: 10.3390/pharmaceutics14061149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/01/2022] [Accepted: 04/03/2022] [Indexed: 02/05/2023] Open
Abstract
Trans-resveratrol can promote various dermatological effects. However, its high crystallinity decreases its solubility and bioavailability. Therefore, solid dispersions have been developed to promote its amorphization; even so, they present as powders, making cutaneous controlled drug delivery unfeasible and an alternative necessary for their incorporation into other systems. Thus, polyvinylpyrrolidone (PVP) films were chosen with the aim of developing a controlled delivery system to treat inflammation and bacterial infections associated with atopic dermatitis. Four formulations were developed: two with solid dispersions (and trans-resveratrol) and two as controls. The films presented with uniformity, as well as bioadhesive and good barrier properties. X-ray diffraction showed that trans-resveratrol did not recrystallize. Fourier-transform infrared spectroscopy (FT-IR) and thermal analysis evidenced good chemical compatibilities. The in vitro release assay showed release values from 82.27 ± 2.60 to 92.81 ± 2.50% (being a prolonged release). In the in vitro retention assay, trans-resveratrol was retained in the skin, over 24 h, from 42.88 to 53.28%. They also had low cytotoxicity over fibroblasts. The in vivo assay showed a reduction in inflammation up to 66%. The films also avoided Staphylococcus aureus’s growth, which worsens atopic dermatitis. According to the results, the developed system is suitable for drug delivery and capable of simultaneously treating inflammation and infections related to atopic dermatitis.
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Gleason KK. Controlled Release Utilizing Initiated Chemical Vapor Deposited (iCVD) of Polymeric Nanolayers. Front Bioeng Biotechnol 2021; 9:632753. [PMID: 33634089 PMCID: PMC7902001 DOI: 10.3389/fbioe.2021.632753] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/05/2021] [Indexed: 11/29/2022] Open
Abstract
This review will focus on the controlled release of pharmaceuticals and other organic molecules utilizing polymeric nanolayers grown by initiated chemical vapor deposited (iCVD). The iCVD layers are able conform to the geometry of the underlying substrate, facilitating release from one- and two-dimensional nanostructures with high surface area. The reactors for iCVD film growth can be customized for specific substrate geometries and scaled to large overall dimensions. The absence of surface tension in vapor deposition processes allows the synthesis of pinhole-free layers, even for iCVD layers <10 nm thick. Such ultrathin layers also provide rapid transport of the drug across the polymeric layer. The mild conditions of the iCVD process avoid damage to the drug which is being encapsulated. Smart release is enabled by iCVD hydrogels which are responsive to pH, temperature, or light. Biodegradable iCVD layers have also be demonstrated for drug release.
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Affiliation(s)
- Karen K Gleason
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
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Unger K, Coclite AM. Conformal Coating of Powder by Initiated Chemical Vapor Deposition on Vibrating Substrate. Pharmaceutics 2020; 12:E904. [PMID: 32972030 PMCID: PMC7558006 DOI: 10.3390/pharmaceutics12090904] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/02/2020] [Accepted: 09/18/2020] [Indexed: 12/05/2022] Open
Abstract
Encapsulation of pharmaceutical powders within thin functional polymer films is a powerful and versatile method to modify drug release properties. Conformal coating over the complete surface of the particle via chemical vapor deposition techniques is a challenging task due to the compromised gas-solid contact. In this study, an initiated chemical vapor deposition reactor was adapted with speakers and vibration of particles was achieved by playing AC/DC's song "Thunderstruck" to overcome the above-mentioned problem. To show the possibilities of this method, two types of powder of very different particle sizes were chosen, magnesium citrate (3-10 µm, cohesive powder) and aspirin (100-500 µm, good flowability), and coated with poly-ethylene-glycol-di-methacrylate. The release curve of coated magnesium citrate powder was retarded compared to uncoated powder. However, neither changing the thickness coating nor vibrating the powder during the deposition had influence on the release parameters, indicating, that cohesive powders cannot be coated conformally. The release of coated aspirin was as well retarded as compared to uncoated aspirin, especially in the case of the powder that vibrated during deposition. We attribute the enhancement of the retarded release to the formation of a conformal coating on the aspirin powder.
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Affiliation(s)
| | - Anna Maria Coclite
- Institute of Solid State Physics, Graz University of Technology, 8010 Graz, Austria;
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Kräuter M, Tazreiter M, Perrotta A, Coclite AM. Deposition of Ion-Conductive Membranes from Ionic Liquids via Initiated Chemical Vapor Deposition. Macromolecules 2020; 53:7962-7969. [PMID: 32981970 PMCID: PMC7513469 DOI: 10.1021/acs.macromol.0c01258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/21/2020] [Indexed: 11/30/2022]
Abstract
In this study, liquid droplets of 1-allyl-3-methylimidazolium dicyanamide have been processed by initiated chemical vapor deposition (iCVD) with a cross-linked polymer film consisting of (hydroxyethyl)methacrylate and ethylene glycol dimethacrylate to develop free-standing, ion-conductive membranes. We found that the obtained films are solids and have a conductivity of up to 18 ± 6 mS/cm, associated with the negatively charged counterion, indicating no loss of conductivity, compared to the ionic liquid in the liquid state. The membranes were conductive within a large process window and in air, thanks to the fact that the iCVD process does not affect the mobility of the anion in the ionic liquid. Furthermore, we demonstrate that varying the deposition conditions can influence the homogeneity and conductivity of the resulting membranes. The promising results of this study represent an important stepping stone on the way to novel ion-conductive membranes.
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Affiliation(s)
- Marianne Kräuter
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Martin Tazreiter
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Alberto Perrotta
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Anna Maria Coclite
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
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Muralter F, Greco F, Coclite AM. Applicability of Vapor-Deposited Thermoresponsive Hydrogel Thin Films in Ultrafast Humidity Sensors/Actuators. ACS APPLIED POLYMER MATERIALS 2020; 2:1160-1168. [PMID: 32201862 PMCID: PMC7076731 DOI: 10.1021/acsapm.9b00957] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/23/2019] [Indexed: 06/02/2023]
Abstract
Thermoresponsive polymers reversibly react to changes in temperature and water content of their environment (i.e., relative humidity, RH). In the present contribution, the thermoresponsiveness of poly(N-vinylcaprolactam) thin films cross-linked by di(ethylene glycol) divinyl ether deposited by initiated chemical vapor deposition are investigated to assess their applicability to sensor and actuator setups. A lower critical solution temperature (LCST) is observed at around 16 °C in aqueous environment, associated with a dramatic change in film thickness (e.g., 200% increase at low temperatures) and refractive index, while only thermal expansion of the polymeric system is found, when ramping the temperature in dry atmosphere. In humid environment, we observed a significant response occurring in low RH (already below 5% RH), with the moisture swelling the thin film (up to 4%), but mainly replacing air in the polymeric structure up to ∼40% RH. Non-temperature-dependent swelling is observed up to 80% RH. Above that, thermoresponsive behavior is also demonstrated to be present in humid environment for the first time, whereas toward 100% RH, film thickness and index appear to approach the values obtained in water at the respective temperatures. The response times are similar in a large range of RH and are faster than the ones of the reference humidity sensor used (i.e., seconds). A sensor/actuator hygromorphic device was built by coating a thin flower-shaped poly(dimethylsiloxane) (PDMS) substrate with the thermoresponsive polymer. The large swelling due to water uptake upon exposure to humid environment at temperatures below the LCST caused the petals to bend, mimicking the capability of plants to respond to environmental stimuli via reversible mechanical motion.
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Muralter F, Coclite AM, Werzer O. Wrinkling of an Enteric Coating Induced by Vapor-Deposited Stimuli-Responsive Hydrogel Thin Films. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:24165-24171. [PMID: 31602284 PMCID: PMC6778969 DOI: 10.1021/acs.jpcc.9b07340] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/30/2019] [Indexed: 06/10/2023]
Abstract
In this contribution, we report on the thin-film synthesis of a thermoresponsive polymer onto another polymer used as an enteric coating in drug applications. In particular, we deposit cross-linked poly(N-vinylcaprolactam) (pNVCL) thin films by initiated chemical vapor deposition (iCVD) onto spin-coated Eudragit (EUD) layers. Already upon iCVD synthesis, the layered structure starts to form wrinkles at a minimum iCVD thickness of 30 nm. By changing the EUD layer thickness and the amount of cross-linking used during iCVD, the morphology of the wrinkles is demonstrated to be readily tunable. Laterally, the double-layer structures vary in morphology from being ultrasmooth to exhibiting up to a 3.5 μm wrinkle wavelength. The surface roughness and, thus, the wrinkles' height can be tailored from below 1 nm up to 100 nm. From the resulting wavelength of wrinkles, an estimation of the elastic modulus of pNVCL proves its tunability over a wide range of values thanks to the iCVD process. This study elucidates an uncomplicated way to tune the wrinkles' morphology and, thus, the surface area of a system that can be employed in drug delivery applications. Hence, an enteric coating of EUD together with an iCVD-synthesized thermoresponsive thin film is proposed as a promising composite encapsulation layer to outperform established systems in terms of tunability of the response to multiple external stimuli.
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Affiliation(s)
- Fabian Muralter
- Institute
for Solid State Physics, NAWI Graz, Graz
University of Technology, 8010 Graz, Austria
| | - Anna Maria Coclite
- Institute
for Solid State Physics, NAWI Graz, Graz
University of Technology, 8010 Graz, Austria
| | - Oliver Werzer
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
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Muralter F, Perrotta A, Werzer O, Coclite AM. Interlink between Tunable Material Properties and Thermoresponsiveness of Cross-Linked Poly( N-vinylcaprolactam) Thin Films Deposited by Initiated Chemical Vapor Deposition. Macromolecules 2019; 52:6817-6824. [PMID: 31579141 PMCID: PMC6764023 DOI: 10.1021/acs.macromol.9b01364] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/12/2019] [Indexed: 11/30/2022]
Abstract
![]()
In
this contribution, we report on the thin-film synthesis of a
novel thermoresponsive polymer, namely, poly(N-vinylcaprolactam)
cross-linked by di(ethylene glycol)divinyl ether [p(NVCL-co-DEGDVE)] by initiated chemical vapor deposition (iCVD). Its transition
between swollen and shrunken states in film thickness and the corresponding
lower critical solution temperature (LCST) was investigated by spectroscopic
ellipsometry in water. Water contact angle measurements and nano-indentation
experiments reveal that the transition is accompanied by a change
in wettability and elastic modulus. The amount of cross-linking was
used to tune the thermoresponsive behavior of the thin films, resulting
in higher swelling and LCST, increased surface rearrangement, and
lower stiffness for less cross-linked polymers. For the first time,
the filament temperature during iCVD synthesis was used to vary the
chain length of the resulting polymeric systems and, thus, the position
of their thermoresponsive transition. With that, swelling of up to
250% compared to the dry thickness and transition temperatures ranging
from 16 to 40 °C could be achieved.
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Affiliation(s)
- Fabian Muralter
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Alberto Perrotta
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Oliver Werzer
- Institute of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, Universitaetsplatz 1, 8010 Graz, Austria
| | - Anna Maria Coclite
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
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