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Tailoring the collagen film structural properties via direct laser crosslinking of star-shaped polylactide for robust scaffold formation
摘要： Application of restructured collagen-based biomaterials is generally restricted by their poor mechanical properties, which ideally must be close to those of a tissue being repaired. Here, we present an approach to the formation of a robust biomaterial using laser-induced curing of a photosensitive star-shaped polylactide. The created collagen-based structures demonstrated an increase in the Young’s modulus by more than an order of magnitude with introduction of reinforcing patterns (from 0.15±0.02 MPa for the untreated collagen to 51.2±5.6 MPa for the reinforced collagen). It was shown that the geometrical configuration of the created reinforcing pattern affected the scaffold’s mechanical properties only in the case of a relatively high laser radiation power density, when the effect of accumulated thermomechanical stresses in the photocured regions was significant. Photo-crosslinking of polylactide did not compromise the scaffold’s cytotoxicity and provided fluorescent regions in the collagen matrix, that create a potential for noninvasive monitoring of such materials’ biodegradation kinetics in vivo.
关键词： mechanical properties,collagen,reinforcements,photopolymerization,biocompatible polymers,riboflavin
更新于2025-11-21 11:24:58
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Effect of Er:YAG laser irradiation and chitosan biomodification on the stability of resin/demineralized bovine dentin bond
摘要： Objective: The purpose of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan on the microtensile bond strength (μTBS), adhesive interface, dry mass loss and hydroxyproline release (HYP). Methods: Artificial lesions were created in 104 bovine dentin blocks. Blocks were divided according to caries removal method: bur or Er:YAG laser. Seventy-six blocks were acid etched and subdivided according to dentin biomodification: no chitosan and 2.5% chitosan. Composite resin restorations were performed. Blocks were sectioned into beams and stored in water. After 24 h, 6 and 12 months, beams were submitted to μTBS test (n = 10) and analysis of adhesive interface by SEM (n = 3). The other 28 blocks were sectioned into beams and initial dry mass (DM) was determined (n = 7). Beams were stored and after 7 days, DM was redetermined. HYP release (n = 7) was evaluated by ELISA. Data were analyzed by ANOVA and Bonferroni's tests (α = 0.05). Results: After 24 h, the highest μTBS was found for bur (p < 0.001). After 6 months, methods were similar (p = 0.432). After 12 months, laser-irradiated dentin showed the highest μTBS values (p = 0.025). Chitosan promoted higher μTBS values after 6 (p = 0.011) and 12 months (p < 0.001) preserving adhesive interface. Dry mass loss and HYP release were not influenced (p > 0.05) by caries removal method or by dentin biomodification. Conclusion: The bond strength to demineralized dentin reduced over 50% in all groups after water storage. From 6 months of water storage, Er:YAG laser irradiation and biomodification with chitosan maintained the stability of the resin-dentin bonds, but did not influence dry mass loss and HYP release.
关键词： μTBS,Hydroxyproline,Lasers,Demineralized dentin,Collagen
更新于2025-11-21 11:18:25
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Quantification of collagen fiber structure using second harmonic generation imaging and two-dimensional discrete Fourier transform analysis: Application to the human optic nerve head
摘要： Second Harmonic Generation (SHG) microscopy is widely used to image collagen fiber microarchitecture due to its high spatial resolution, optical sectioning capabilities and relatively non-destructive sample preparation. Quantification of SHG images requires sensitive methods to capture fiber alignment. This paper presents a 2D Discrete Fourier Transform (DFT) based method for collagen fiber structure analysis from SHG images. The method includes integrated Periodicity Plus Smooth Image Decomposition (PPSID) for correction of DFT edge discontinuity artefact, avoiding the loss of peripheral image data encountered with more commonly used windowing methods. Outputted parameters are: the collagen fiber orientation distribution, aligned collagen content and the degree of collagen fiber dispersion along the principal orientation. We demonstrate its application to determine collagen microstructure in the human optic nerve head, showing its capability to accurately capture characteristic structural features including radial fiber alignment in the innermost layers of the bounding sclera and a circumferential collagen ring in the mid-stromal tissue. Higher spatial resolution rendering of individual lamina cribrosa beams within the nerve head is also demonstrated. Validation of the method is provided in the form of correlative results from wide-angle X-ray scattering (WAXS) and application of the presented method to other fibrous tissues.
关键词： Second Harmonic Generation,edge effect artefact correction,Discrete Fourier Transform,optic nerve head,collagen fiber structure,Non-linear microscopy
更新于2025-09-23 15:23:52
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Luminescent Lanthanide–Collagen Peptide Framework for pH-Controlled Drug Delivery
摘要： Collagen mimetic scaffolds play a pivotal role in regenerative medicine and tissue engineering due to their extraordinary structural and biological features. We have herein for the first time reported the construction of luminescent lanthanide-collagen peptide hybrid three-dimensional nanofibrous scaffolds, which well mimic the characteristic architectural structure of native collagen. Three collagen mimetic peptides composed of repetitive central (GPO)7 sequences and altered terminal amino acids, have been shown to consistently self-assemble to form biocompatible nanofibers under the trigger of a variety of lanthanide ions, which also functionalize the assembled materials with easily tunable photoluminescence. Furthermore, the collagen peptide-lanthanide hybrid scaffolds possess programmable pH-responsive features. The lanthanide ion-mediated assembly of all the three collagen peptides are conveniently and reversibly regulated by pH, while their pH-dependent patterns are finely tuned by the identity of terminal amino acids. Using camptothecin and cefoperazone sodium as two model drugs, the drug-loading and releasing efficiency of the collagen peptide-lanthanide scaffolds are nicely modulated by pH, demonstrating the efficacy of these nanofibrous scaffolds as pH-responsive drug carriers. These novel luminescent collagen peptide-lanthanide scaffolds provide a facile system for pH-controlled drug delivery, suggesting promising applications in the development of therapies for many diseases.
关键词： self-assembly,scaffold,pH-responsive,Collagen mimetic peptides,drug delivery
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE XXV International Conference on Electronics, Electrical Engineering and Computing (INTERCON) - Lima (2018.8.8-2018.8.10)] 2018 IEEE XXV International Conference on Electronics, Electrical Engineering and Computing (INTERCON) - An Algorithm for The Quantification of Lipids, Collagen and Muscle Cells in Coronary Arteries Based on Digital Image Processing
摘要： The present study presents a method to quantify lipids, collagen and muscle cells, to help diagnose atherosclerosis using digital image processing techniques. The relative concentrations of these three indicators are crucial in diagnosing atherosclerosis in patients. Digital image processing techniques such as object detection, color enhancement, and shape and texture analysis were used to quantify cells. The objective of the algorithm is to analyze high definition images of coronary arteries and to provide an objective outcome on the atherosclerotic tissue stage. The algorithm presented outstanding results and an innovative method to diagnose atherosclerosis when compared to existing procedures in the literature.
关键词： coronary heart tissue,lipids,quantification,muscle cells,Digital Image Processing,collagen
更新于2025-09-23 15:23:52
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Monitoring dynamic collagen reorganization during skin stretching with fast polarization-resolved SHG imaging
摘要： The mechanical properties of biological tissues are strongly correlated to the specific distribution of their collagen fibers. Monitoring the dynamic reorganization of the collagen network during mechanical stretching is however a technical challenge because it requires mapping orientation of collagen fibers in a thick and deforming sample. In this work, a fast polarization-resolved SHG microscope is implemented to map collagen orientation during mechanical assays. This system is based on line-to-line switching of polarization using an electro-optical modulator and works in epidetection geometry. After proper calibration, it successfully highlights the collagen dynamic alignment along the traction direction in ex vivo murine skin dermis. This microstructure reorganization is quantified by the entropy of the collagen orientation distribution as a function of the stretch ratio. It exhibits a linear behavior, whose slope is measured with a good accuracy. This approach can be generalized to probe a variety of dynamic processes in thick tissues.
关键词： biomechanics,multiphoton microscopy,skin,polarization,collagen
更新于2025-09-23 15:23:52
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Changes in the Collagen Structure of Thyroid Nodule Capsules Determined by Polarization-Resolved Second Harmonic Generation Microscopy
摘要： Thyroid carcinomas represent a challenging problem as their differentiation from the much more frequent benign pathologies can be sometimes difficult. Automatic diagnostic approaches that can differentiate between malignant and benign thyroid nodules would be of great benefit for addressing thyroid pathologies. In this study we have used polarization-resolved second harmonic generation microscopy to investigate collagen organization in the fibrillar capsules surrounding human thyroid nodules. We demonstrate that imaging the collagen capsules at different laser beam polarization angles and fitting the second harmonic generation intensity with a theoretical curve can yield information on the nonzero components of the second order susceptibility tensor and the orientation of the collagen fibres. We have used this approach to differentiate between capsules surrounding the thyroid follicular adenoma and papillary carcinoma nodules. These results indicate that polarization-resolved second harmonic generation microscopy can provide additional information about the collagenous capsule surrounding thyroid nodules, which may complement intensity-based quantitative second harmonic generation microscopy and eventually traditional histopathologic examination.
关键词： second harmonic generation,thyroid nodules,collagen
更新于2025-09-23 15:22:29
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Six-month outcomes of corneal crosslinking with dextran-free isotonic riboflavin solution
摘要： Purpose: To analyze the short-term clinical and topographic outcomes in patients with keratoconus after corneal collagen cross-linking treatment (CXL) with dextran-free isotonic riboflavin solution. Methods: In this retrospective case series, 26 eyes from 26 patients with keratoconus were studied. The best corrected visual acuity (BCVA) and refractive and topographic findings were analyzed at a 6-month follow-up. Results: The mean BCVA (Snellen lines) values before and 1, 3, and 6 months after CXL were 0.51 ± 0.2, 0.48 ± 0.2, 0.57 ± 0.2, and 0.64 ± 0.2, respectively, and the difference between the preoperative and 6-month values was statistically significant (p=0.006). The mean spherical equivalent refraction decreased from -5.6 ± 2.4 diopters (D) preoperatively to -5.0 ± 2.1 D, and mean simulated keratometry decreased from 48.5 ± 2.5 D to 47.8 ± 2.6 D at 6 months. (p=0.145 and p=0.001, respectively). In addition, the maximum keratometry decreased progressively and significantly from the preoperative value during follow-up (p=0.003). The central and minimal corneal thicknesses, including those of the epithelium, also decreased from 442.8 ± 25.6 μm and 430.5 ± 23.9 μm preoperatively to 420.7 ± 31.8 μm and 409.3 ± 28.7 μm at the most recent follow-up (p<0.001), respectively. No intraoperative or postoperative complications were observed. Conclusions: CXL with dextran-free isotonic riboflavin solution appears to be a safe treatment alternative for keratoconus and yields sustained short-term improvements in visual acuity, keratometric readings, and corneal thickness. However, long-term results are needed to confirm these outcomes.
关键词： Dextrans,Riboflavin/therapeutic use,Collagen,Visual acuity,Ultraviolet rays,Cornea,Cross-linking reagents
更新于2025-09-23 15:22:29
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Maturation of the Meniscal Collagen Structure Revealed by Polarization-Resolved and Directional Second Harmonic Generation Microscopy
摘要： We report polarization-resolved Second Harmonic Generation (p-SHG) and directional SHG (forward and backward, F/B) measurements of equine foetal and adult collagen in meniscus, over large field-of-views using sample-scanning. Large differences of collagen structure and fibril orientation with maturation are revealed, validating the potential for this novel methodology to track such changes in meniscal structure. The foetal menisci had a non-organized and more random collagen fibrillar structure when compared with adult using P-SHG. For the latter, clusters of homogeneous fibril orientation (inter-fibrillar areas) were revealed, separated by thick fibers. F/B SHG showed numerous different features in adults notably, in thick fibers compared to interfibrillar areas, unlike foetal menisci that showed similar patterns for both directions. This work confirms previous studies and improves the understanding of meniscal collagen structure and its maturation, and makes f/B and p-SHG good candidates for future studies aiming at revealing structural modifications to meniscus due to pathologies.
关键词： Second Harmonic Generation,meniscus,directional SHG,polarization-resolved,collagen
更新于2025-09-23 15:21:01
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Stimulation of collagen and elastin production in-vivo using 1,540??nm Er:Glass laser: assessment of safety and efficacy
摘要： Introduction: Induction of collagen and elastin remodeling in the human skin can be achieved by non-ablative fractional laser (NAFXL) and ablative fractional laser (AFXL). Our objective was to compare the safety, efficacy, tolerability, and ability to induce collagen and elastin remodeling of NAFXL versus AFXL in a series of treatments over time. Materials and Methods: In this prospective, proof of principle, single-case study, the safety, tolerability and efficacy of the laser systems were assessed via histopathology and clinical evaluations including photographs. Optical biopsies by means of multiphoton tomography (MPT) were used to evaluate the induction of collagen and elastin remodeling. Results: Treatments by both NAFXL and AFXL were well tolerated. The NAFXL system was found to be less painful and resulted in a shorter down- and healing times. MPT findings showed the superior capability of the AFXL procedure to induce collagen; on the other hand, elastin induction was more pronounced after NAFXL treatments. Conclusions: While NAFXL is as effective and safe as the traditional AFXL, it is better tolerated and has a shorter downtime. Serial optical biopsies over time over time can be a useful tool to assess the induction of collagen and elastin remodeling in the human skin.
关键词： remodeling,optical biopsy,10600 nm,ablative,collagen,multi-photon tomography,non-ablative,fractional,elastin,140 nm,Laser
更新于2025-09-23 15:21:01