Emerging SERS and TERS MoS2 platforms for the characterization of plasma-derived extracellular vesicles

Extracellular vesicles (EVs) play a crucial role in intercellular communication processes. In addition, their biomolecular cargoes such as lipids, proteins, and nucleic acids are useful for identifying potential biomarkers related to different stages of cancer disease. However, the small size and heterogenicity of tumor-related EVs represent a major challenge in properly identifying the content of EVs' cargoes with common characterization protocols. To address these issues, surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) are powerful alternatives to assign the vibrational fingerprints to the biomolecules contained in cancer EVs, providing high specificity and spatial resolution. Transition metal dichalcogenides are particularly interesting as SERS and TERS substrates due to the high sensitivity of their 2D surface through coulombic and van der Waals interactions when in contact with an analyte or small object such as the charged membranes of EVs. These interactions induce subtle changes in the work function of the flakes which can be measured through drastic changes of optical processes. We investigate the use of MoS2 flakes synthesized by atmospheric pressure chemical vapor deposition as a potential label-free SERS and TERS platform for the identification of plasma EVs. To exemplify this technology, we isolated plasma EV samples from donors with early-stage [FIGO (I/II)] with high-grade serous carcinoma (HGSC) by size exclusion chromatography (SEC). Both surface- and tip-enhanced measurements were conducted individually, enabling the identification of a series of markers from ovarian cancer donors, highlighting the complementarity of SERS and TERS measurements.

Additive-manufactured paper-PMMA hybrid microfluidic chip for simultaneous monitoring of creatinine and pH in artificial urine

Nowadays, kidney dysfunction is a common health issue due to the modernized lifestyle. Even though medications are commercially available to treat kidney diseases, early diagnosis is crucial and challenging. Clinically, measuring urine creatinine and pH has gained significant interest as a way to diagnose kidney diseases early. In the present work, we attempted to develop a low-cost, robust, accurate and naked-eye colorimetric method to determine both creatinine levels and pH variations in artificial urine samples using a simple 3D-printed hybrid microfluidic device. Creatinine was detected by the incorporation of the traditional Jaffe test onto the hybrid paper-PMMA microfluidic device and pH (4-8) was measured by a simple anthocyanin test. Notably, the tests were established without employing any sophisticated or costly instrument clusters. The developed 3D-printed microfluidic probe showed a limit of detection (LOD) of 0.04 mM for creatinine over a concentration range of 1-10 mM, with a regression coefficient (R2) of 0.995 in laboratory conditions. Interestingly, the experimental data obtained with artificial urine exhibited a wide linear range from 0.1 mM to 5 mM under different pH values ranging from 4 to 8 in the presence of matrices commonly found in urine samples other than proteins, indicating the potential use of this method in pre-clinical analysis. Since the wide linear range of urine creatinine in artificial urine samples falls well below the clinically relevant concentrations in humans (0.07-0.27 mM), the developed lab-on-chip device is further suitable for clinical evaluation with proper ethical clearance. This 3D-printed hybrid microfluidic colorimetry-based creatinine detection and pH indicator platform can be beneficial in the healthcare sector due to the on-site testing capability, cost-effectiveness, ease of use, robustness, and instrument-free approach.

Transformative applications of additive manufacturing in biomedical engineering: bioprinting to surgical innovations

This paper delves into the diverse applications and transformative impact of additive manufacturing (AM) in biomedical engineering. A detailed analysis of various AM technologies showcases their distinct capabilities and specific applications within the medical field. Special emphasis is placed on bioprinting of organs and tissues, a revolutionary area where AM has the potential to revolutionize organ transplantation and regenerative medicine by fabricating functional tissues and organs. The review further explores the customization of implants and prosthetics, demonstrating how tailored medical devices enhance patient comfort and performance. Additionally, the utility of AM in surgical planning is examined, highlighting how printed models contribute to increased surgical precision, reduced operating times, and minimized complications. The discussion extends to the 3D printing of surgical instruments, showcasing how these bespoke tools can improve surgical outcomes. Moreover, the integration of AM in drug delivery systems, including the development of innovative drug-loaded implants, underscores its potential to enhance therapeutic efficacy and reduce side effects. It also addresses personalized prosthetic implants, regulatory frameworks, biocompatibility concerns, and the future potential of AM in global health and sustainable practices.

Multiscale Mechanical Characterization of Polyether-2-ketone (PEKK) for Biomedical Application

Polyether-ether-2-ketone (PEKK) is a high-performance thermoplastic polymer used in various fields, from aerospace to medical applications, due to its exceptional mechanical and thermal properties. Nonetheless, the mechanical behavior of 3D-printed PEKK still deserves to be more thoroughly investigated, especially in view of its production by 3D printing, where mechanical properties measured at different scales are likely to be correlated to one another and to all play a major role in determining biomechanical properties, which include mechanical strength on one side and osteointegration ability on the other side. This work explores the mechanical behavior of 3D-printed PEKK through a multiscale approach, having performed both nanoindentation tests and standard tensile and compression tests, where a detailed view of strain distribution was achieved through Digital Image Correlation (DIC) techniques. Furthermore, for specimens tested up to failure, their fractured surfaces were analyzed through Scanning Electron Microscopy (SEM) to clearly outline fracture modes. Additionally, the internal structure of 3D-printed PEKK was explored through Computed Tomography (CT) imaging, providing a three-dimensional view of the internal structure and the presence of voids and other imperfections. Finally, surface morphology was analyzed through confocal microscopy. The multiscale approach adopted in the present work offers information about the global and local behavior of the PEKK, also assessing its material properties down to the nanoscale. Due to its novelty as a polymeric material, no previous studies have approached a multiscale analysis of 3D-printed PEKK. The findings of this study contribute to a comprehensive understanding of 3D-printed PEKK along with criteria for process optimization in order to customize its properties to meet specific application requirements. This research not only advances the knowledge of PEKK as a 3D-printing material but also provides insights into the multifaceted nature of multiscale material characterization.

Nanomaterials-incorporated hydrogels for 3D bioprinting technology

In the field of tissue engineering and regenerative medicine, various hydrogels derived from the extracellular matrix have been utilized for creating engineered tissues and implantable scaffolds. While these hydrogels hold immense promise in the healthcare landscape, conventional bioinks based on ECM hydrogels face several challenges, particularly in terms of lacking the necessary mechanical properties required for 3D bioprinting process. To address these limitations, researchers are actively exploring novel nanomaterial-reinforced ECM hydrogels for both mechanical and functional aspects. In this review, we focused on discussing recent advancements in the fabrication of engineered tissues and monitoring systems using nanobioinks and nanomaterials via 3D bioprinting technology. We highlighted the synergistic benefits of combining numerous nanomaterials into ECM hydrogels and imposing geometrical effects by 3D bioprinting technology. Furthermore, we also elaborated on critical issues remaining at the moment, such as the inhomogeneous dispersion of nanomaterials and consequent technical and practical issues, in the fabrication of complex 3D structures with nanobioinks and nanomaterials. Finally, we elaborated on plausible outlooks for facilitating the use of nanomaterials in biofabrication and advancing the function of engineered tissues.

Effect of stem cell secretome in skin rejuvenation: a narrative review

PURPOSE

Cutaneous aging is an inevitable biological process that develops over time due to cumulative cellular and molecular changes caused by exposure to intrinsic (chronological aging) and extrinsic (photo-aging) factors on the skin. Skin aging is characterized by a decline in the body's capability to sustain senescence, dermal cell apoptosis, and homeostasis. Stem cell secretions (secretome) are defined as the total set of dynamically overlapping paracrine soluble growth factors, cytokines, chemokines, angiogenic factors, extracellular matrix proteins, and antimicrobial peptides known to be responsible for tissue rejuvenation, regeneration, homeostasis, and immunomodulation.

METHODS

In this review, we summarized the molecular and regulatory mechanism of the secretome in preventing the skin aging process, as well as its capacity in inducing skin rejuvenation. Furthermore, we illustrated secretome efficiency as an anti-aging therapeutic strategy based on in vitro and in vivo published studies.

RESULTS

In all reviewed publications, the secretome has been proven to be the most effective treatment for aged skin, capable of reversing the aging process through the action of cytokines, growth factors, and collagen, which are its primary components. The reported mechanism of action involves modulating the signaling pathways of aging and replenishing the skin with collagen, fibronectin, and elastin, ultimately resulting in skin renewal and rejuvenation.

CONCLUSION

In conclusion, compared to available treatments, the secretome shows great promise as an anti-aging therapy.

Comparative culture of human corneal endothelial cells following treatment with human platelet lysate/fibrin hydrogel versus Y-27632 ROCK inhibitor: in vitro and ex vivo study

PURPOSE

The advancement of tissue engineering and cell therapy research has resulted in innovative therapeutic options for patients with corneal endothelial diseases. The aim of this study was to compare the potential effect of using human platelet lysate (HPL)/Fibrin hydrogel versus using a Y-27632 ROCK inhibitor, on the culture of human corneal endothelial cells (HCECs) under in vitro and ex vivo conditions.

METHODS

HCECs were isolated from human donors and treated separately with HPL/Fibrin hydrogel, a Y-27632 ROCK inhibitor, and fetal bovine serum (FBS). MTT viability assay and cell counting were performed on the treated cells. Subsequently, we prepared ex vivo models of human corneal endothelial dysfunction and incubated them with DiI-labeled-HCECs. Specular and fluorescence microscopy were then performed on each of the ex vivo models.

RESULTS

In comparison, similar viability results were achieved in the cells treated with HPL/Fibrin hydrogel versus those treated with the Y-27632 ROCK inhibitor, but both treatments showed higher viability than the control group (FBS). More importantly, based on the specular and fluorescence microscopic results, the HPL/Fibrin hydrogel and the Y-27632 ROCK inhibitor treatments showed similar inducible effects on the attachment of the cells to the Descemet membranes of the ex vivo models.

CONCLUSION

HPL/Fibrin hydrogel and Y-27632 ROCK inhibitor have similar inducible effects on the viability and attachment of the HCECs. A definite advantage of treating cells with HPL/Fibrin hydrogel is that it serves as a xeno-free and biocompatible material which can have autologous applications in future usage by clinics.

An Isolation System to Collect High Quality and Purity Extracellular Vesicles from Serum

Purpose

Extracellular vesicles (EVs) are membrane-encapsulated nanoparticles that function as carriers and play a role in intercellular communication. There are a large number of EVs in the blood and serve as an indicator of pathophysiological conditions. Studies on the basics and application of EVs are hampered by the limitations of current protocols to isolate EVs from blood. However, current isolation methods are difficult to achieve a balance between yield and purity.

Methods

Firstly, we use Sepharose-4B to build a self-made size exclusion chromatography (SEC) column and perform separation and characteristics. Then, we use the SEC column to systematically compare the efficiency with the most common EV isolation methods: Ultracentrifugation (UC) and total exosomes isolation commercial kit (TEI). The EVs isolated through different methods were characterized the yield and size of EVs, analyzed their protein profiles, the morphology and purity were observed under the transmission electron microscope. To further improve the quality and purity, we combined SEC and UC methods and established a two-steps method to isolated EVs from serum.

Results

Self-made SEC column can well separate EVs from complex serum protein, and EVs enriched in the 8–13 fractions with good morphology and yield. By systematically compare SEC with the commonly used UC and TEI kit, SEC is outstanding in all aspects and balances both isolation purity and yield. However, using the SEC method alone still has certain limitations and residual impurities. The SEC+UC combined method can cleverly solve the shortcomings of SEC and optimize the quality and purity of EVs from serum, which is much better than using one method alone.

Conclusion

Our study presents the combination of size-exclusion chromatography and ultracentrifugation as a feasible and time-saving method to isolate high-quality and purity extracellular vesicles from serum.

Effect of different fabrication methods of occlusal devices on periradicular stress distribution: A photoelastic analysis

STATEMENT OF PROBLEM

Investigations on the effectiveness of new methods for optimizing the fabrication of oral devices are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate stress distribution with photoelastic analysis in the periradicular area of teeth supporting occlusal devices fabricated by 5 different processes.

MATERIAL AND METHODS

The occlusal devices were fabricated by vacuum thermoforming, heat-polymerized acrylic resin, chemical polymerized acrylic resin, 3-dimensional printing, and milling (computer-aided manufacturing). The devices were evaluated regarding initial fit, number of adjustments for passive fit, and stress distribution under 100-N and 400-N loads in the periradicular locations of posterior teeth.

RESULTS

The 3-dimensional printing device did not require any adjustment for initial adaptation to the photoelastic model and presented a little friction with the model. The heat-polymerized acrylic resin device did not seat initially, requiring more sites of adjustment until passive adaptation. At 100-N and 400-N loads, the use of the computer-aided manufacturing occlusal device resulted in the lowest stresses in periradicular areas (0.744 and 1.583, respectively), and the 3-dimensional printing occlusal device produced the highest stresses with a 400-N load application (2.427). The lowest mean of fringe pattern was observed for the computer-aided manufacturing device, and the highest mean of fringe pattern was observed for the vacuum thermoforming device.

CONCLUSIONS

The computer-aided design and computer-aided manufacturing milled occlusal device presented the best initial adaptation and transferred lower stresses to the periradicular areas than the other evaluated devices.

Additive Manufacturing of Polymer Materials: Progress, Promise and Challenges

The use of additive manufacturing (AM) has moved well beyond prototyping and has been established as a highly versatile manufacturing method with demonstrated potential to completely transform traditional manufacturing in the future. In this paper, a comprehensive review and critical analyses of the recent advances and achievements in the field of different AM processes for polymers, their composites and nanocomposites, elastomers and multi materials, shape memory polymers and thermo-responsive materials are presented. Moreover, their applications in different fields such as bio-medical, electronics, textiles, and aerospace industries are also discussed. We conclude the article with an account of further research needs and future perspectives of AM process with polymeric materials.

The Emerging Potential of Extracellular Vesicles in Cell-Free Tissue Engineering and Regenerative Medicine

Extracellular vesicles (Evs) are membrane-enclosed vesicles secreted by all cell types that mediate cell-cell communication via their protein, lipid, carbohydrate, and nucleic acid (RNA, DNA) cargo. EVs are involved in a multitude of physiological processes, including development, cell differentiation, and angiogenesis, and have been implicated in tissue repair. Thus, they have been suggested to offer opportunities for the development of novel cell-free tissue engineering (TE) approaches. In this review, we provide an overview of current understanding and emerging applications of EVs in TE and address opportunities and challenges for clinical translation. In addition, we discuss systemic and local routes of delivery of EVs and the advantages and disadvantages of different biomaterials in providing a substrate for the sustained release of EVs in vivo. Impact statement Extracellular vesicles (EVs) are nanoscale, membrane-bound vesicles released by most, if not all, cells in the body. They are implicated in a wide range of physiological processes and diseases ranging from cancer to neurodegeneration, and hold huge potential as mediators of tissue regeneration. This has led to an explosion of interest in using EVs in a variety of tissue engineering applications. In this review, we provide an overview of current progress in the field and highlight the opportunities and challenges of harnessing the potential of EVs in regenerative medicine.