1,421 research outputs found
Data for: Electrospun nanofiber-based niflumic acid capsules with superior physicochemical properties
No full textDataset for the article titled 'Electrospun nanofiber-based niflumic acid capsules with superior physicochemical properties&apos
Noted Author and Scholar Visits
Full text linkThe new Cassandra Voss Center at St. Norbert is celebrating a canonical figure in gender studies in America with a full year of programming dedicated to her work.https://digitalcommons.snc.edu/snc_magazine_archives_2013-2018/1004/thumbnail.jp
Summer 2013: Community-Wide Conversation Focuses on Recruiting and Retaining Young Talent
Full text linkA significant discussion on regional progress – and ways to relay that progress to members of Generation Y, in particular – kicked off at St. Norbert on Oct. 15. Futurist, economist and author Rebecca Ryan talked about means by which communities like the Greater Green Bay area can enhance their ability to recruit and retain the next generation of talent.https://digitalcommons.snc.edu/snc_magazine_archives_2013-2018/1084/thumbnail.jp
In a Class by Himself
Full text linkThis year, for the first time, an alumni presenter will be among those taking part in Alumni College. C.J. Hribal ’79, author and Marquette University professor, will offer a lecture on the art of mystery in fiction. Hribal joins St. Norbert professors (some of them SNC alums, too!) on the faculty of the annual event that draws alums back to campus for a weekend opportunity to reconnect.https://digitalcommons.snc.edu/snc_magazine_archives_2013-2018/1002/thumbnail.jp
Norbert Waszek, "La escuela hegeliana"
No full textAuthor: Norbert Waszek. Translated by Pedro Sepúlveda Zambran
Norbert Waszek, "La escuela hegeliana"
Full text linkAuthor: Norbert Waszek. Translated by Pedro Sepúlveda Zambran
Spring 2015: Thought Leaders Weigh Issues of Violence and Reconciliation
Full text linkThe “Thought Leaders Weigh Issues of Violence and Reconciliation” article from St. Norbert College Magazine’s Spring 2015 issue recounts a powerful dialogue between author bell hooks and sociologist Beth Richie during hooks’ campus residency. Centered on the theme “Ending Violence: How We Change,” the conversation explored systemic violence, personal accountability, and the transformative potential of love and community. Richie, an advisor to the NFL on domestic violence, and hooks, a renowned social justice scholar, emphasized the need for honest dialogue, healing, and grassroots change—urging individuals to start small, act locally, and build inclusive spaces of understanding and care.https://digitalcommons.snc.edu/snc_magazine_archives_2013-2018/1244/thumbnail.jp
Wearable and Stretchable Strain Sensors: Materials, Sensing Mechanisms, and Applications
Full text linkRecent advances in the design and implementation of wearable resistive, capacitive, and optical strain sensors are summarized herein. Wearable and stretchable strain sensors have received extensive research interest due to their applications in personalized healthcare, human motion detection, human–machine interfaces, soft robotics, and beyond. The disconnection of overlapped nanomaterials, reversible opening/closing of microcracks in sensing films, and alteration of the tunneling resistance have been successfully adopted to develop high-performance resistive-type sensors. On the other hand, the sensing behavior of capacitive-type and optical strain sensors is largely governed by their geometrical changes under stretching/releasing cycles. The sensor design parameters, including stretchability, sensitivity, linearity, hysteresis, and dynamic durability, are comprehensively discussed. Finally, the promising applications of wearable strain sensors are highlighted in detail. Although considerable progress has been made so far, wearable strain sensors are still in their prototype stage, and several challenges in the manufacturing of integrated and multifunctional strain sensors should be yet tackled
Electrospinning for skin tissue engineering and drug-eluting antimicrobial biomaterials
Full text linkA critical challenge in the design of biomaterials for tissue engineering relies on the development of tissue-specific biomimetic scaffolds capable of replacing cell-matrix interactions required for the repair of injured tissues. Further, such biomaterials with the additional capacity to prevent bacteria contamination can resolve issues surrounding surgical prosthesis infection. Fibrous micro- and nanostructures are extensively researched in tissue engineering due to their intrinsic similarities to decellularised human tissues. Among the several fibre-forming processes, electrospinning has drawn much attention due to its ability to produce scaffolds that morphologically resemble the native extracellular matrix (ECM) of human tissues.
Electrospinning is a versatile method that uses electrohydrodynamic principles to produce fibres with diameters ranging from microns to tens of nanometres. By varying the chemistry and morphology of the fibres, it is feasible to attain different physiological and mechanical responses. The wide array of raw natural and synthetic materials – including polymers and complex molecules – that can be used to electrospin fibres can resolve well-documented problems associated with the inferiority of synthetic biomaterials and the limitations of biological tissues.
In this thesis, electrospinning is utilised to contribute to the engineering of advanced ECM-mimicking biomaterials. The work will focus on (1) improving the physicochemical and mechanical responses of skin substitutes and (2) preventing mesh-associated surgical site infection.
The initial study of this thesis presents the design and construction of a nozzle-free electrospinning device, which is an economically viable method of scaling-up fibre production output. The equipment is then used to fabricate elastic skin-like composite nanofibres consisting of poly(vinylpyrrolidone) (PVP) and poly(glycerol sebacate) (PGS). The findings indicate that the mechanical properties of the electrospun mats could be tuned by varying the concentration of PGS and the molecular weight of PVP within the blends. Photocrosslinking the fibres prevented the rapid degradation of the composite mats due to the hydrophilic nature of PVP, making it feasible to assess the biological responses of the construct in vitro, displaying good viability and proliferation of human dermal fibroblasts. This study provides a different approach towards the development of skin substitutes, based on the fact that mechanical stimuli influence the ability of dermal cells to adapt and reconstruct the ECM at an injured site; being able to adjust the mechanics to those of different anatomical sites of the body can have a positive effect on the overall outcome of a healing wound.
Synthetic biomaterials tend to present suboptimal cell growth and proliferation, with many studies linking this phenomenon to the hydrophobicity of such surfaces. This thesis continues with the development of a protocol for silk fibroin extraction from Bombyx mori cocoons, which achieved significantly increased yields of the protein in a third of the time required by the conventional molecular cut-off extraction approach. The extracted silk fibroin was then used to produce electrospun membranes consisting of poly(caprolactone) (PCL) blended with variant forms of PGS. The main aim of this work was the development of fibre mats with tuneable hydrophobicity/hydrophilicity properties, depending on the esterification degree and concentration of PGS within each composite. By altering the surface properties of the electrospun membranes, the trinary composite biomaterial presented improved fibroblast attachment behaviour and optimal growth in comparison to PCL-only fibrous mats.
The study continued with the development of an ultralight-weight nanostructured bicomponent antimicrobial construct with a similar microstructure to biologic meshes, which preserved the required mechanical integrity of synthetic mesh materials. A core/shell nanofibrous structure was developed, consisting of nylon-6 in the core and chitosan/polyethylene oxide in the shell. The bicomponent fibre structure comprised a binary antimicrobial system incorporating 5-chloro-8-quinolinol in the chitosan-shell, with the sustained release of polyhexamethylene biguanide from the nylon-6 core of the fibres. The antimicrobial nanofibres were found to elicit a robust bactericidal response, in vitro, against the two most commonly occurring pathogenic bacteria in deep incisional surgical site infections; Staphylococcus aureus and Pseudomonas aeruginosa. The results of this study advocate that the bicomponent nanofibres developed can be a promising alternative to biologic meshes, employed for hernia repair today, due to similar architecture and mechanics, but at the same time capable of actively protecting the patient from subsequent mesh-associated infections, thus tackling this life-threatening postoperative complication.
Overall, the work in this thesis has expanded upon the fields of skin tissue engineering and drug-eluting antimicrobial biomaterials, potentially guiding new areas of research
Fabrication of tubular constructs using hybrid extrusion printing and electrospinning for vascular tissue engineering applications
Full text linkCardiovascular disease is the leading cause of mortality in the world, with the number
of deaths rising every year. Coronary artery disease, peripheral artery disease,
aneurysm, and strokes are the most prominent forms of vascular diseases. Bypass
surgery is one of the techniques performed to treat these vascular diseases, which
involves the re-routing of blood flow around the blocked arterial site using a vascular
graft. Autologous grafts, such as saphenous vein and internal mammary artery, remain
a gold standard for bypass grafting procedures. However, the removal of autologous
grafts often results in the donor site morbidity. In some cases, the grafts are
unavailable due to previous harvest or poor quality. Synthetic grafts represent an
alternate option, however, they usually fail when used as small diameter bypass grafts.
The mismatch between the mechanical properties of synthetic grafts and native
arteries is the major cause of failure of these synthetic grafts made from PET and
ePTFE. Therefore, there is an urgent and high demand to fabricate a vascular conduit
having biomechanical behaviour similar to that of the native arteries.
In this thesis, a new hybrid extrusion printing and electrospinning technique is
presented to fabricate vascular grafts. A commercially available Creality3D Ender 3D
printer was modified into a hybrid setup having a vertical mandrel, an extrusion printing
head, and electrospinning heads. The setup is capable of fabricating layered structure
using hydrogel and electrospun nanofibres. The gelatin methacryloyl (gelMA) hydrogel
was selected for printing tubular constructs as it is widely used in the literature to
encapsulate cells for bioprinting. Polycaprolactone (PCL) and Poly (L-lactide-co-ε-
caprolactone) (PLCL) polymers were used to produce electrospun nanofibres for the
reinforcement of hydrogel conduits. The setup was successfully tested to print grafts
around the rotating mandrel.
Bioprinting is an attractive technique to print tissues using hydrogels. However,
printing of long tubular constructs from hydrogels remains a challenge. Additive-lathe
printing method offers a solution to print grafts with high aspect ratios but printing
hydrogels around the horizontal rods often leads to sagging, which results in the
non-uniform wall thickness and subsequently variable mechanical properties.
A new approach of printing around the vertical mandrel was used to fabricate gelMA grafts
having uniform wall thickness. The printing parameters were selected to achieve the
overlapping of two consecutive printed filaments, which resulted in the better bonding
of filaments and good quality tubular constructs were fabricated. The tensile testing
results revealed that the anisotropic properties of printed gelMA grafts were similar to
those observed in the natural blood vessels. Moreover, no leakage was detected in
the printed gelMA tubular constructs during the burst pressure measurement. Thus, a
vertical additive-lathe printing method offers an attractive technique to print long
vascular grafts using hydrogels.
The burst pressure of the gelMA grafts printed on vertical additive-lathe printing setup
was found to be lower than the normal haemodynamic blood pressures. Therefore, a
reinforcement is required. A layer of electrospun nanofibres was collected over the
printed hydrogel constructs to improve the mechanical performance. Various blends
of Polycaprolactone (PCL) and poly(L-lactide-co-ε-caprolactone) (PLCL) polymer
solutions were used to produce electrospun nanofibres. The printed bi-layered
vascular grafts showed mechanical properties close to that of the native arteries. The
tensile strength of the 12% gelMA constructs reinforced by 100/0 PCL/PLCL blend
fibres was found to be greater than 3 MPa, which falls in the range of tensile strength
value of native arteries (0.5 – 3 MPa for coronary arteries and 1.5 – 4 MPa for radial
and mammary arteries). The fabricated vascular grafts showed a burst pressure of
more than 2000 mmHg, which is within the range of burst pressure values for the
human saphenous vein (1250 – 2476 mmHg) and radial artery (2001 – 2476 mmHg).
Moreover, the compliance values of gelMA constructs reinforced by 100/0 PCL/PLCL
(6.85 ± 1.01 %/100mmHg) and 75/25 PCL/PLCL (17.13 ± 7.35 %/100mmHg) were
found to be similar to the muscular arteries (6.03 ± 3.39 %/100mmHg) and elastic
arteries (16.21 ± 3.81 %/100mmHg), respectively. The cytocompatibility assessment
showed that gelMA presented a bioactive surface for the endothelial cells to survive
and grow.
The newly developed hybrid setup has been utilized to fabricate fibre-reinforced
vascular grafts. The mechanical performance of these constructs was found to be
similar to that of native arteries. Also, PCL/PLCL fibres showed good cellular metabolic
activity and gelMA surfaces were biocompatible for the HUVECs to grow. Thus, the
presented fabrication method has a great potential to fabricate vascular grafts having
biomechanical properties similar to that of natural blood vessels
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