3D high-resolution two-photon crosslinked hydrogel structures for biological studies

Brigo, Laura; Urciuolo, Anna; Giulitti, Stefano; Giustina, Gioia Della; Tromayer, Maximilian; Liska, Robert; Elvassore, Nicola; Brusatin, Giovanna

doi:10.1016/j.actbio.2017.03.036

Cited by 76 publications

(73 citation statements)

References 22 publications

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“…The peptide chain can be easily modified to insert (metha)acrylate functionalities that can undergo 2PP in the presence of a photoinitiator. Different groups prepared 3D structures using only modified Gelatin, as a blend with a crosslinker (to achieve a better resolution), or even as composite matrix . The scaffolds produced with such methodologies retained their biocompatibility and promoted cells attachment and differentiation …”

Section: Biomaterial‐based Resinsmentioning

confidence: 99%

Functional Materials for Two‐Photon Polymerization in Microfabrication

Carlotti

Mattoli

2019

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The creation of 3D micro and nanostructures is of particular interest in the fields of photonics, [3] microelectromechanical systems (MEMS), [4] metamaterials, [5] micro/ nanofluidics, [6] cellular proliferation, and differentiation. [7] To create 3D objects of arbitrary shape, 3D printing techniques offer many versatile solutions. [8] Among these, direct laser writing (DLW) allows for the simple preparation of (sub)micrometric objects and patterns with a resolution that can go below 100 nm. [9][10][11] DLW is an additive manufacturing technique based on twophoton polymerization (2PP). To produce a structure, a fs-pulsed long-wavelength laser is focused, by means of optical elements, in a photosensitive resin which is able to crosslink (negative photoresist) or decompose (positive photoresist) under an energetic radiation but that is also transparent at the laser wavelength: if the intensity of the excitation radiation is high enough-as it is the case in the focus-the resin can undergo two (or more)-photon absorption and polymerize (or decompose). [12] Such multiphotons absorption phenomena are nonlinear and the cross-section of the different materials scales with the square (or higher) of the intensity of the radiation. For these reasons, the laser beam can enter the photoresist without being absorbed and trigger the photochemical process(es) only in a small volume around the focus. This volume is named "voxel" being the 3D analogue of a 2D pixel. [13] The absorption probability outside of the voxel is small, thus suppressing the propagation of the reaction and resulting in fine resolution. By moving around the voxel, one can obtain complex 3D structures that can be isolated after developing. [14,15] More than two decades have passed since DLW was proposed [16] and much progress has been made in terms of improving feature size and resolution, [9,[17][18][19][20][21] enlarging the library of materials that can be used, [22][23][24][25] and the possible applications of these finely controlled structures. [6,[25][26][27][28] The research on functional materials-here intended as materials that can be employed in 2PP and show peculiar features that encourage their use in particular applications-has propelled the field of micro/nanostructuring forward by promoting the interdisciplinarity between chemistry, physics, biology, and material science. [26] In this review, we will summarize and critically discuss the different functional materials proposed in the literature, dividing them and confronting them according to their preparation and their application (Figure 1; Table 1). We start the main body discussing the properties and applications of nanocomposite resists used in 2PP. In the second part, Direct laser writing methods based on two-photon polymerization (2PP) are powerful tools for the on-demand printing of precise and complex 3D architectures at the micro and nanometer scale. While much progress was made to increase the resolution and the feature size throughout the years, by carefully designing a material, one...

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Section: Biomaterial‐based Resinsmentioning

confidence: 99%

Functional Materials for Two‐Photon Polymerization in Microfabrication

Carlotti

Mattoli

2019

Small

176

126

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“…Cylindrical gyroidal structures (50 % external porosity, 500 µm wall thickness) were printed and then dehydrated in 70 %, 80 %, 90 % and 100 % ethanol, with each step performed three times for 10 min. The gyroids were then transferred to HMDS for 2 min, HMDS was then removed and samples were left to dry [28,29]. Subsequently, the cylinders were immersed in liquid nitrogen and snapped into halves, gold sputter coated and SEM imaged.…”

Section: Qualitative Characterisation Of Porous Networkmentioning

confidence: 99%

Direct 3D printing of monolithic ion exchange adsorbers

Simon

Dimartino

2019

Journal of Chromatography A

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Monolithic adsorbers with anion exchange (AEX) properties have been 3D printed in an easy one-step process, i.e. not requiring post-functionalization to introduce the AEX ligands. The adsorber, 3D printed using a commercial digital light processing (DLP) printer, was obtained by copolymerisation of a bifunctional monomer bearing a positively charged quaternary amine as well as an acrylate group, with the biocompatible crosslinker polyethylene glycol diacrylate (PEGDA). To increase the surface area, polyethylene glycol was introduced into the material formulation as pore forming agent. The influence of photoinitiator (Omnirad 819) and photoabsorber (Reactive Orange 16, RO16) concentration was investigated in order to optimize printing resolution, allowing to reliably 3D print features as small as 200 µm and of highly complex Schoen gyroids. Protein binding was measured on AEX adsorbers with a range of ligand densities (0.00, 2.03, 2.60 and 3.18 mmol/mL) using bovine serum albumin (BSA) and c-phycocyanin (CPC) as model proteins. The highest equilibrium binding capacity was found for the material presenting the lowest ligand density analysed (2.03 mmol/mL), adsorbing 73.7 ± 5.9 mg/mL and 38.0 ± 2.2 mg/mL of BSA and CPC, respectively. This novel 3D printed material displayed binding capacities in par or even higher than commercially available chromatographic resins. We expect that the herein presented approach of using bifunctional monomers, bearing commonly used chromatography ligands, will help overcome the material limitations currently refraining 3D printing applications in separation sciences.

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“… 4 , 13 − 22 ( Figure 1 A) As a result, a photo-cross-linkable derivative is obtained that is suitable for laser-based rapid prototyping techniques including two photon polymerization (2PP). 5 , 6 , 23 − 25 Important material limitations remain, however, in terms of mechanical and swelling properties after cross-linking. Consequently, several strategies were proposed to tackle this issue: varying the degree of substitution, grafting of other biomolecules, 26 the formation of interpenetrating networks, 27 or combining the gelatin with a second (synthetic) material (e.g., polyesters) to increase the overall stiffness of the final construct.…”

Section: Introductionmentioning

confidence: 99%

Cross-Linkable Gelatins with Superior Mechanical Properties Through Carboxylic Acid Modification: Increasing the Two-Photon Polymerization Potential

et al. 2017

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The present work reports on the development of photo-cross-linkable gelatins sufficiently versatile to overcome current biopolymer two-photon polymerization (2PP) processing limitations. To this end, both the primary amines as well as the carboxylic acids of gelatin type B were functionalized with photo-cross-linkable moieties (up to 1 mmol/g) resulting in superior and tunable mechanical properties (G′ from 5000 to 147000 Pa) enabling efficient 2PP processing. The materials were characterized in depth prior to and after photoinduced cross-linking using fully functionalized gelatin-methacrylamide (gel-MOD) as a benchmark to assess the effect of functionalization on the protein properties, cross-linking efficiency, and mechanical properties. In addition, preliminary experiments on hydrogel films indicated excellent in vitro biocompatibility (close to 100% viability) both in the presence of MC3T3 preosteoblasts and L929 fibroblasts. Moreover, 2PP processing of the novel derivative was superior in terms of applied laser power (≥40 vs ≥60 mW for gel-MOD at 100 mm/s) as well as post-production swelling (0–20% vs 75–100% for gel-MOD) compared to those of gel-MOD. The reported novel gelatin derivative (gel-MOD-AEMA) proves to be extremely suitable for direct laser writing as both superior mimicry of the applied computer-aided design (CAD) was obtained while maintaining the desired cellular interactivity of the biopolymer. It can be anticipated that the present work will also be applicable to alternative biopolymers mimicking the extracellular environment such as collagen, elastin, and glycosaminoglycans, thereby expanding current material-related processing limitations in the tissue engineering field.

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3D high-resolution two-photon crosslinked hydrogel structures for biological studies

Cited by 76 publications

References 22 publications

Functional Materials for Two‐Photon Polymerization in Microfabrication

Functional Materials for Two‐Photon Polymerization in Microfabrication

Direct 3D printing of monolithic ion exchange adsorbers

Cross-Linkable Gelatins with Superior Mechanical Properties Through Carboxylic Acid Modification: Increasing the Two-Photon Polymerization Potential

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