Student Projects

Enhancing Porosity in Electrospun Scaffolds via Dual-Nozzle Fabrication with Sacrificial Materials

Electrospinning is a widely used technique for fabricating fibrous scaffolds that mimic the extracellular matrix of native cartilage. However, conventional electrospun scaffolds often suffer from poor cell infiltration due to their dense and randomly organized fiber networks. This project aims to improve scaffold porosity by implementing a dual-nozzle electrospinning approach, combining a structural polymer (e.g., PCL) with a sacrificial material that can later be removed to create larger interconnected pores. The master’s student will optimize the fabrication process, develop a protocol for selective material removal, and characterize the resulting scaffolds. This work supports the development of more functional and biologically relevant synthetic analogs for cartilage tissue engineering.

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Cartilage Tissue Engineering Biofabrication Electrospinning Biomaterials

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Semester Project , Internship , Master Thesis

Description

Osteoarthritis (OA) is the most prevalent musculoskeletal disorder globally, affecting over 32.5 million adults in the United States alone. Commonly referred to as degenerative joint disease or "wear-and-tear" arthritis, OA is a multifactorial, typically slow-progressing, and largely non-inflammatory condition that arises from pathological changes in various synovial joint tissues, including articular cartilage, subchondral bone, ligaments, periarticular muscles, peripheral nerves, and the synovium. These changes lead to cartilage degradation, bone remodeling, joint pain, stiffness, and loss of mobility and function. Solution electrospinning (SES) is a widely used technique for fabricating nanofibrous poly(ε-caprolactone) (PCL) scaffolds for cartilage tissue engineering. While SES enables the production of fibrous matrices that resemble the extracellular matrix, conventional electrospun scaffolds often suffer from limited control over fiber alignment and pore structure. Their dense and randomly organized fibers hinder cellular infiltration, an essential feature for successful tissue regeneration. To overcome this limitation, strategies such as using fast-degrading polymers (e.g., poly(glycerol sebacate), PGS) or enhancing scaffold porosity through architectural modifications have been proposed. The goal of this project is to improve the porosity and cell-infiltration capacity of electrospun scaffolds by employing dual-nozzle electrospinning to incorporate a sacrificial material alongside PCL fibers. Once removed, the sacrificial component will create additional pore spaces within the scaffold structure. The student will be responsible for developing and optimizing a dual electrospinning protocol, including: • Selection and processing of suitable polymer blends; • Fine-tuning electrospinning parameters for both materials; • Evaluating scaffold morphology, fiber distribution, and porosity through imaging techniques; • Testing the effectiveness of sacrificial material removal. This project offers hands-on experience in advanced scaffold fabrication and supports ongoing efforts to design more biomimetic and functional constructs for cartilage regeneration.

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Published since: 2025-07-16 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa

Topics Engineering and Technology

Adapting Open-Source G-Code Tools for Customized Melt Electrowriting of Cartilage Scaffolds

We are seeking a motivated and technically inclined master’s student to join our research team in the optimization of melt electrowriting (MEW) for cartilage tissue engineering. MEW is an emerging additive manufacturing technique that enables the fabrication of micro- and nanoscale scaffolds with highly controlled architectures, ideally suited for mimicking the extracellular matrix of native cartilage. Our group employs a custom-built MEW device for scaffold fabrication, historically operated via proprietary software. To enhance design flexibility and streamline G-code generation, this project focuses on adapting an open-source, MATLAB-based G-code tool developed by international collaborators. The student will analyze and modify the existing tool to ensure compatibility with our specific MEW setup, followed by experimental validation through scaffold printing and performance testing. In the context of a master’s thesis, the adapted tool will also be used to fabricate advanced scaffold geometries to support downstream biological studies. This interdisciplinary project offers hands-on experience in biofabrication, programming, and tissue engineering, contributing to the development of next-generation therapies for osteoarthritis.

Keywords

Tissue engineering Biofabrication Biomaterials Coding

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Semester Project , Internship , Master Thesis

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Published since: 2025-07-16 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa , Amicone Alessio

Topics Engineering and Technology

Enhancing Cell Compatibility of Melt-Electrowritten PCL Scaffolds for Articular Cartilage Regeneration: Investigating the Influence of NaOH Treatment

Osteoarthritis (OA) is a widespread degenerative joint disease characterized by the progressive breakdown of articular cartilage, resulting in pain, stiffness, and reduced mobility. Current clinical treatments fail to fully restore the structural and functional properties of native cartilage, highlighting the need for innovative tissue engineering strategies. This project focuses on the development and surface modification of polycaprolactone (PCL) scaffolds fabricated by melt electrowriting (MEW)—a technique that enables the creation of highly organized, microscale fibrous architectures suitable for cartilage regeneration. While PCL is widely used for scaffold fabrication due to its biocompatibility and mechanical properties, its hydrophobic surface limits cellular attachment and function, particularly for sensitive cell types such as chondrocytes. To address this, the project investigates the effect of alkaline surface treatment using sodium hydroxide (NaOH) on the morphology, hydrophilicity, and biological performance of MEW scaffolds. The study systematically varies NaOH concentration and exposure time to evaluate the resulting changes in chondrocyte viability and extracellular matrix (ECM) production, including key markers like glycosaminoglycans (GAGs) and collagen. The goal is to determine whether NaOH treatment can enhance scaffold–cell interactions without compromising structural integrity, ultimately supporting the development of a more effective platform for cartilage tissue engineering. The project combines scaffold fabrication, surface chemistry, and biological assays to provide a comprehensive understanding of how surface modifications influence chondrocyte behavior and tissue formation within a defined 3D microenvironment.

Keywords

Cartilage Tissue Engineering Melt-electrowriting Biomaterials Surface Modification

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Semester Project , Internship , Master Thesis

Description

Osteoarthritis (OA) is the most prevalent musculoskeletal disorder worldwide, affecting over 32.5 million adults in the United States alone [1]. Commonly referred to as “wear-and-tear” arthritis or degenerative joint disease, OA is a multifactorial, typically slow-progressing, and non-inflammatory condition of the synovial joints. It arises from abnormalities in various joint tissues—including articular cartilage, subchondral bone, ligaments, periarticular muscles, synovium, and peripheral nerves—ultimately leading to cartilage degradation, subchondral bone remodeling, pain, stiffness, and reduced joint function [1]. To address cartilage degeneration, tissue engineering strategies have increasingly focused on fibrous scaffolds that mimic the native extracellular matrix. Among the most promising fabrication techniques are solution electrospinning (SES) and melt electrowriting (MEW), both capable of producing fibrous structures suitable for cartilage regeneration [2]. SES generates nanoscale fibers with a random, non-woven morphology, limiting spatial control over fiber deposition. In contrast, MEW allows for precise placement of microfibers via a programmable stage, enabling the creation of organized architectures and anisotropic scaffolds [3,4]. Polycaprolactone (PCL) is widely used in both SES and MEW due to its biocompatibility, biodegradability, and mechanical properties. However, its hydrophobic surface limits cell adhesion and interaction, making surface modification a key area of interest. One common strategy to enhance surface wettability and introduce bioactive functional groups is wet chemical treatment, particularly using alkaline hydrolysis. In this method, NaOH is applied to cleave ester bonds on the polymer surface, generating hydroxyl and carboxyl groups that improve hydrophilicity [5]. Additionally, this treatment can induce micropitting and surface roughness, which has been shown to enhance cell adhesion and proliferation [6]. The degree of modification is tunable through the adjustment of NaOH concentration and exposure time. While the effects of NaOH surface treatment on electrospun PCL membranes have been studied, its impact on melt electrowritten (MEW) PCL scaffolds, particularly regarding chondrocyte viability and extracellular matrix (ECM) formation, remains unexplored. MEW scaffolds offer a more defined and controllable architecture compared to electrospun meshes, which can significantly influence cell behavior. Given the sensitivity of chondrocytes to substrate properties, it is essential to evaluate how alkaline surface modification affects their viability, morphology, and ability to synthesize key cartilage ECM components, such as glycosaminoglycans (GAGs) and collagen. This investigation will help determine whether NaOH treatment can enhance the biological performance of MEW scaffolds and support their application in cartilage tissue engineering.

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Published since: 2025-07-15 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa

Topics Engineering and Technology

Multiscale Scaffold Design for Osteoarthritis Treatment: A Comparative Study of Hydrogel Pore Formation and Visualization Strategies

Osteoarthritis (OA) is a progressive joint disorder characterized by the degradation of articular cartilage, affecting millions of individuals worldwide and posing a significant clinical and socioeconomic burden. Current treatment strategies remain limited in their ability to restore the structural and functional integrity of damaged cartilage. This project aims to engineer a biomimetic multiscale scaffold that combines fibrous and hydrogel components to replicate the hierarchical architecture and mechanical behavior of native cartilage tissue. The fibrous framework is fabricated using solution electrospinning (SES) and melt electrowriting (MEW) to integrate nanoscale and microscale features, respectively, thereby enhancing mechanical strength and guiding cellular organization. The fibrous network is embedded within a macroporous hydrogel matrix, designed to support high water content and efficient nutrient transport while promoting cell viability and matrix production. A central focus of the project is the optimization of hydrogel pore architecture using two approaches: cryogelation and porogen incorporation. These methods will be systematically compared to determine their effectiveness in creating interconnected pore networks. To evaluate and visualize gel structure under physiologically relevant (hydrated) conditions, the project will establish a fluorescent labeling and confocal microscopy protocol, enabling detailed pore size and distribution analysis. The final composite constructs will be characterized morphologically, mechanically, and biologically, including testing with human chondrocytes to assess cytocompatibility and extracellular matrix production. This work aims to contribute to the development of next-generation scaffolds for cartilage tissue regeneration, offering a promising approach toward functional repair of osteoarthritic joints.

Keywords

Cartilage Tissue Engineering Biomaterials Hydrrogels

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Semester Project , Internship , Master Thesis

Description

Osteoarthritis (OA) is the most prevalent musculoskeletal disorder globally, affecting over 32.5 million adults in the United States alone. Also referred to as degenerative joint disease or “wear-and-tear” arthritis [1], OA is a multifactorial, progressive, and typically non-inflammatory condition of the synovial joints. It can arise from structural and functional abnormalities in any of the joint tissues, including articular cartilage, subchondral bone, ligaments, periarticular muscles, peripheral nerves, and synovium. These pathological changes lead to the degradation of cartilage and bone, resulting in joint pain, stiffness, and loss of mobility [1]. To address current limitations in cartilage repair, we propose a composite scaffold consisting of a fibrous multiscale component, fabricated using solution electrospinning (SES) and melt electrowriting (MEW), and a hydrogel matrix. SES and MEW are established techniques for producing nanofibrous constructs suitable for cartilage tissue engineering [2]. While SES generates fiber meshes with random orientation, limiting spatial control, MEW allows for precise, programmable deposition of microscale fibers due to its additive manufacturing-like approach, combining aspects of electrospinning and fused deposition modeling [3,4]. The composite scaffold design leverages the mechanical integrity and tunable architecture of the fibrous layers, while the hydrogel phase provides a highly hydrated, bioactive environment with favorable transport properties for cell proliferation and nutrient diffusion. This strategy aims to overcome the inherent limitations of each component, particularly the hydrophobicity of PCL and the poor mechanical strength of conventional hydrogels. To optimize the performance of the hydrogel phase, we aim to enhance its internal porosity. Two main strategies are under consideration: (1) cryogelation, which involves crosslinking at sub-zero temperatures to form macroporous structures, and (2) the use of porogens, removable particles or agents that generate pores upon leaching. While the first method has already been thoroughly investigated, we now intend to explore and optimize the porogen-based approach. A critical step will be identifying porogens that are compatible with the hydrogel environment and application. Once both methods have been evaluated, we plan to characterize and compare the resulting pore architecture under hydrated conditions. Recent findings suggest that the internal morphology of hydrogels, specifically pore size and distribution, can be visualized using fluorescent dyes such as fluorescein isothiocyanate (FITC) [5,6], providing a non-destructive and reproducible method for assessing pore structure. The aim of this study is to engineer and characterize a composite scaffold that closely mimics the structural and functional properties of native articular cartilage. A particular focus will be placed on optimizing hydrogel porosity and fiber architecture to support chondrocyte viability, integration, and matrix production under physiologically relevant conditions.

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Published since: 2025-07-15 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa

Topics Engineering and Technology

Enhancing Interlayer Integration and Mechanical Properties in Electrospun and Melt-Electrowritten Scaffolds

This project focuses on improving the mechanical performance and interlayer integration of multiscale scaffolds for articular cartilage tissue engineering. By combining solution electrospinning (SES) and melt electrowriting (MEW), the study aims to fabricate layered fibrous constructs with enhanced structural integrity. A key objective is to explore annealing as a post-processing technique to strengthen the interface between electrospun and MEW layers, addressing a common limitation in scaffold delamination. Morphological and mechanical properties will be assessed through scanning electron microscopy and mechanical testing, with optional biological evaluation using bovine chondrocytes. We are seeking a motivated master's student to contribute to scaffold fabrication, characterization, and cell-based studies within this interdisciplinary research project.

Keywords

Cartilage Tissue engineering Solution Electrospinning Meltelectrowriting Biofabrication Biomaterials

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Semester Project , Internship , Master Thesis

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Published since: 2025-07-10 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa

Topics Engineering and Technology

Optimization of Electrospinning and Melt-Electrowriting Parameters with a new triblock copolymer

Osteoarthritis (OA), the most prevalent musculoskeletal disorder, leads to degeneration of synovial joints, including articular cartilage. While solution electrospinning (SES) and melt electrowriting (MEW) of poly(ε-caprolactone) (PCL) have shown promise for fabricating fibrous scaffolds for cartilage repair, PCL's low elasticity and slow degradation hinder clinical translation. This project explores a new triblock copolymer, PLLA-b-PCL-b-PLLA, to overcome these limitations. The research aims to optimize SES and MEW parameters and enhance mechanical integrity through annealing of multiscale scaffolds. Scaffold morphology and mechanics will be assessed via SEM and mechanical testing, while biological performance will be evaluated using bovine chondrocytes. The project offers a master's student the opportunity to contribute to the development of improved biomimetic scaffolds for cartilage regeneration.

Keywords

Cartilage Tissue Engineering Solution Electrospinning Meltelectrowriting Biomaterials Biofabrication

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Semester Project , Internship , Master Thesis

Description

Osteoarthritis (OA) affects over 32.5 million US adults and is the most common musculoskeletal condition worldwide. It is also known as degenerative joint disease or “wear and tear” arthritis [1]. OA is a multifactorial, usually slow-progressing, and non-inflammatory disorder of the synovial joints that results from abnormalities in any of the synovial joint tissues, including articular cartilage, subchondral bone, ligaments, periarticular muscles, peripheral nerves, or synovium. This leads to the breakdown of cartilage and bone, resulting in pain, stiffness, and functional disability [1]. Solution Electrospinning (SES) and Melt-Electrowriting (MEW) are well-established methods for fabricating nanofibrous constructs for articular cartilage regeneration [2]. Solution electrospinning typically produces matrices characterized by stochastic fibers, limiting control over fiber deposition. Achieving precise control over the alignment and arrangement of fibers is critical for tissue engineering applications that require the guided release of proteins and growth factors [3,4]. Scaffolds are materials that cannot recapitulate the full complexity of tissue. By combining multiple biofabrication techniques, appropriate biomechanical/biophysical cues might improve tissue remodeling and thus the applicability of scaffolds for complex tissue. The gold standard for both the above-mentioned techniques is Poly(ε-caprolactone) (PCL) due to its low melting temperature, excellent melt flow properties and thermal stability. In addition, PCL is semicrystalline, biocompatible, biodegradable, and has also been approved by the U.S. Food and Drug Administration (FDA) for certain clinical purposes. All off the above makes the use of this polymer interesting for biomedical applications. While the use of PCL has yielded promising outcomes in the field of biomedical research, its translation into the clinic is not without challenges. Particularly when integrated in a dynamic environment or in soft tissue applications, PCL shows limitations characterized by low elasticity and especially slow in vivo biodegradation kinetics, increasing the possible risk of inflammation [5]. Therefore the utilization of a triblock-copolymer composed of PCL and PLLA, denoted as PLLA-b-PCL-b-PLLA is proposed.

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Published since: 2025-07-10 , Earliest start: 2025-09-01

Organization Tissue Mechanobiology

Hosts Bissacco Elisa

Topics Engineering and Technology

Pre-clinical mechanical evaluation of a novel spinal implant

Lower back pain is one of the most prevalent health issues in Switzerland, with severe socio-economic consequences and a leading cause of reduced work performance. Approximately 20% of spinal fusion surgeries performed using off-the-shelf implants result in the surgical outcome being compromised post-operatively, often requiring one or more revision surgeries to address the associated pain. The Laboratory of Orthopedic Technology has recently developed a novel spinal implant using topology optimization, which is currently undergoing a feasibility study for clinical applications. We are seeking a master’s student who is passionate about medical devices and mechanical design and testing to join us for a master thesis. In this role, you will gain insight into the spinal surgery process, receive input from surgeons, and contribute to the mechanical testing of the implant on human cadaveric spine. Objectives: • Perform the CT scan on human cadaveric vertebrae • Evaluate the influence of implant placement/location variability • Mechanical testing on the implant and failure mode analysis • Develop surgical tools if needed • Write related SOPs and testing report Your Profile: • Hands-on and detail-oriented, need to work with human cadaveric bones. • Experience with SolidWorks or Fusion 360, as well as Python or Matlab. • Need to have Hepatitis B Vaccine to be able to work in BSL 2 level labs

Keywords

implant, medical device, mechanical testing, clinical application

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Master Thesis

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Published since: 2025-06-10 , Earliest start: 2025-06-23 , Latest end: 2026-01-30

Organization Bone Pathologies and Treatment

Hosts Du Xiaoyu

Topics Medical and Health Sciences