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Injectable shear-thinning biomaterials (STBs) have attracted significant attention because of their efficient and localized delivery of cells as well as various molecules ranging from growth factors to drugs. Recently, electrostatic interaction-based STBs, including gelatin/LAPONITE® nanocomposites, have been developed through a simple assembly process and show outstanding shear-thinning properties and injectability. However, the ability of different compositions of gelatin and LAPONITE® to modulate doxorubicin (DOX) delivery at different pH values to enhance the effectiveness of topical skin cancer treatment is still unclear. Here, we fabricated injectable STBs using gelatin and LAPONITE® to investigate the influence of LAPONITE®/gelatin ratio on mechanical characteristics, capacity for DOX release in response to different pH values, and cytotoxicity toward malignant melanoma. The release profile analysis of various compositions of DOX-loaded STBs under different pH conditions revealed that lower amounts of LAPONITE® (6NC25) led to higher pH-responsiveness capable of achieving a localized, controlled, and sustained release of DOX in an acidic tumor microenvironment. Moreover, we showed that 6NC25 had a lower storage modulus and required lower injection forces compared to those with higher LAPONITE® ratios. Furthermore, DOX delivery analysis in vitro and in vivo demonstrated that DOX-loaded 6NC25 could efficiently target subcutaneous malignant tumors via DOX-induced cell death and growth restriction. This journal is

Various perivascular drug delivery techniques have been demonstrated for localized post-treatment of intimal hyperplasia: a vascular inflammatory response caused by endothelial damages. Although most perivascular devices have focused on controlling the delivery duration of anti-proliferation drug, the confined and unidirectional delivery of the drug to the target tissue has become increasingly important. In addition, careful attention should also be paid to the luminal stability and the adequate exchange of vascular protein or cell between the blood vessel and extravascular tissue to avoid any side effect from the long-term application of any perivascular device. Here, a highly flexible and porous silk fibroin microneedle wrap (Silk MN wrap) is proposed to directly inject antiproliferative drug to the anastomosis sites while ensuring sufficient vascular exchanges. Drug-embedded silk MNs were transfer-molded on a highly flexible and porous silk wrap. The enhanced cell compatibility, molecular permeability, and flexibility of silk MN wrap guaranteed the structural integrity of blood vessels. Silk wrap successfully supported the silk MNs and induced multiple MN penetration to the target tissue. Over 28 days, silk MN wrap significantly inhibited intimal hyperplasia with a 62.1% reduction in neointimal formation.

Background Flowable hemostatic agents are advantageous in that they can be applied to irregular wound surfaces and to areas that are difficult to approach directly. We sought to compare the effectiveness and safety of the flowable hemostatic sealants Collastat® (collagen hemostatic matrix, [CHM]) and Floseal® (gelatin hemostatic matrix, [GHM]) during off-pump coronary artery bypass (OPCAB). Methods In this prospective, randomized trial, 160 patients undergoing elective OPCAB surgery were enrolled between March 2018 and February 2020. After primary suture of the aortocoronary anastomosis, an area of hemorrhage was identified, and patients were double blind randomized to receive either CHM or GHM (n = 80, each). Study endpoints were the following: rate of successful intraoperative hemostasis and time required for hemostasis overall postoperative bleeding, rate of transfusion of blood products, rate of surgical revision for bleeding, postoperative morbidity, and intensive care unit stay. Results Of the total patients, 23% were female, and the mean age was 63 years (range: 42–81 years). Successful hemostasis within 5 min was achieved for 78 patients (97.5%) in the GHM group, compared to 80 patients (100%) in the CHM group (p = 0.497). Two patients receiving GHM required surgical revision to achieve hemostasis. There were no differences in the mean time required to obtain hemostasis (GHM vs. CHM, 1.49 ± 0.94 vs. 1.35 ± 0.60 min, p = 0.272), as confirmed by time-to-event analysis (p = 0.605). The two groups had similar amounts of mediastinal drainage for 24 h postoperatively (p = 0.298). The CHM group required less packed red blood cells, fresh frozen plasma, and platelets for transfusion than the GHM group (0.5 vs. 0.7 units per patient, p = 0.047; 17.5% vs. 25.0%, p = 0.034; 7.5% vs. 15.0%, p = 0.032; respectively). Conclusions CHM performed similarly to a commonly used hemostatic agent with regard to achieving effective and fast interoperative hemostasis during OPCAB. The topical flowable hemostatic agent, CHM, could be effectively used during cardiac surgery for intraoperative hemostasis of great vessels with high pressure. Trial registration : ClinicalTrials.gov, NCT 04310150

Over the decades, researchers have strived to synthesize and modify nature-inspired biomaterials, with the primary aim to address the challenges of designing functional biomaterials for regenerative medicine and tissue engineering. Among these challenges, biocompatibility and cellular interactions have been extensively investigated. Some of the most desirable characteristics for biomaterials in these applications are the loading of bioactive molecules, strong adhesion to moist areas, improvement of cellular adhesion, and self-healing properties. Mussel-inspired biomaterials have received growing interest mainly due to the changes in mechanical and biological functions of the scaffold due to catechol modification. Here, we summarize the chemical and biological principles and the latest advancements in production, as well as the use of mussel-inspired biomaterials. Our main focus is the polydopamine coating, the conjugation of catechol with other polymers, and the biomedical applications that polydopamine moieties are used for, such as matrices for drug delivery, tissue regeneration, and hemostatic control. We also present a critical conclusion and an inspired view on the prospects for the development and application of mussel-inspired materials.

Silk fibroin (SF) is a promising biomaterial for tendon repair, but its relatively rigid mechanical properties and low cell affinity have limited its usefulness and utility in regenerative medicine. Meanwhile, gelatin-based polymers have advantages in cell attachment and tissue remodeling, but have insufficient mechanical strength to regenerate tough tissue such as tendons. Taking these aspects into account, in this study, gelatin methacryloyl (GelMA) was combined with SF to create a mechanically strong and bioactive nanofibrous scaffold (SG). The mechanical properties of SG nanofibers could be flexibly modulated by varying the ratio of SF and GelMA. Compared to SF nanofibers, mesenchymal stem cells (MSCs) seeded on SG fibers with optimal composition (SG7) exhibited enhanced growth, proliferation, vascular endothelial growth factor (VEGF) production and tenogenic gene expression behavior. Conditioned media from MSCs cultured on SG7 scaffolds, compared to MSCs cultured on SF or GelMA alone nanofibers could greatly promote the migration and proliferation of tenocytes. Histological analysis and tenogenesis related immunofluorescence staining indicated SG7 scaffolds demonstrated enhanced in vivo tendon tissue regeneration compared to other groups. Therefore, rational combinations of SF and GelMA hybrid nanofibers may help to improve therapeutic outcomes and address the challenges of tissue-engineered scaffolds for tendon regeneration.

A hyaluronic acid (HA)-based one-pot hydrogel reactor with single syringe injection and immediate gelation was developed for starvation therapy (ST), chemodynamic therapy (CDT), ferroptosis, and photothermal therapy (PTT) against breast cancer. A rheologically tuned hydrogel network, composed of HA-phenylboronic acid (HP) and HA-dopamine (HD), was designed by introducing a boronate ester linkage (phenylboronic acid-dopamine interaction) and polydopamine bond (pH control). Ferrocene (Fc)-conjugated HP (Fc-HP) was synthesized to achieve ferroptosis, Fenton reaction-involved toxic hydroxyl radical (

Fluorescent nanomaterials have been widely used in biological imaging due to their selectivity, sensitivity, and noninvasive nature. These characteristics make the materials suitable for real-time and in situ imaging. However, further development of highly biocompatible nanosystems with long-lasting fluorescent intensity and photostability is needed for advanced bioimaging. We have used electrospraying to generate gelatin methacryloyl (GelMA)-based fluorescent nanoparticles (NPs) with chemically conjugated rhodamine B (RB). The extent of conjugation can be controlled by varying the mass ratio of RB and GelMA precursors to obtain RB-conjugated GelMA (RB-GelMA) NPs with optimal fluorescent properties and particle size. These NPs exhibited superior biocompatibility when compared with pure RB in in vitro cell viability and proliferation assays using multiple cell types. Moreover, RB-GelMA NPs showed enhanced cell internalization and improved brightness compared with unconjugated RB. Our experiments demonstrate that engineered RB-GelMA NPs can be used as a biocompatible fluorescent label for bioimaging.

Intravitreal injection (IVI) is a common technology which is used to treat ophthalmic diseases inside eyeballs by delivering various drugs into the vitreous cavity using hypodermic needles. However, in some cases, there are possible side effects such as ocular tissue damage due to repeated injection or eyeball infection through the hole created during the needle retraction process. The best scenario of IVI is a one-time injection of drugs without needle retraction, keeping the system of the eyeball closed. Microneedles (MNs) have been applied to ocular tissues over 10 years, and no serious side effects on ocular tissue due to MN injection have been reported. Therefore, a self-plugging MN (SPM) is developed to perform intraocular drug delivery and to seal the scleral puncture simultaneously. The SPMs are fabricated by a thermal drawing process and then coated with a polymeric carrier of drugs and a hydrogel-based scleral plugging component. Each coated functional layer is characterized and demonstrated by in vitro and ex vivo experiments. Finally, in vivo tests using a porcine model confirms prompt sealing of SPM and sustained intraocular drug delivery.

In this study, a coaxial electrospray process was used to produce nanoparticles, in which thymol was encapsulated in a core–shell of zein and shellac. We then investigated fluid velocity and solution concentrations on the electrospray. Scanning electron microscopy revealed that the thymol/zein/shellac particles prepared at a flow rate ratio of 0.6:0.3 mL/h were rounder with smaller diameters. The highest encapsulation efficiency of thymol was 81.34%, the average particle size was 606.53 nm, and the retention rate of thymol was 68.74% after 30 days. Moreover, we investigated the thermal stability, antimicrobial activity, and simulated gastrointestinal release curves of the nanoparticles. Finally, the nanoparticles were used as a coating for fresh-cut cantaloupe. Compared with the blank nanoparticle control group, the coating significantly extended the shelf life of cantaloupe to 16 days. Our results indicate that these nanoparticles have great potential for application in food preservation.

In this study, poly (e-caprolactone) (PCL)/zein/Ag nanoparticle (AgNP) fibrous membranes were prepared by ultrasonication-assisted electrospinning. The effects of the AgNP content and ultrasonication time on the membrane morphology, chemical structure, biodegradability, mechanical properties, antibacterial/antiviral activity, and air filtration performance were studied. The best-performing membrane (AgNP content = 1% (w/v), sonication time = 30 min) exhibited a bead-on-string morphology, an air permeability of 93.6 ± 1.5 mm s−1, and the Escherichia coli and Staphylococcus aureus removal efficiencies of 98.1 ± 1.2% and 97.4 ± 2.5%, respectively. In an experiment with E. coli phage, the above-mentioned membrane exhibited a 97.1 ± 2.1% virus removal efficiency after 60 min. The high performance of this bead-on-string membrane for air filtration was ascribed to the low packing density due to the presence of open interconnected beaded airflow channels and small beads.

Made available in DSpace on 2021-06-25T10:22:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 The skin serves a substantial number of physiological purposes and is exposed to numerous biological and chemical agents owing to its large surface area and accessibility. Yet, current skin models are limited in emulating the multifaceted functions of skin tissues due to a lack of effort on the optimization of biomaterials and techniques at different skin layers for building skin frameworks. Here, we use biomaterial-based approaches and bioengineered techniques to develop a 3D skin model with layers of endothelial cell networks, dermal fibroblasts, and multilayered keratinocytes. Analysis of mechanical properties of gelatin methacryloyl (GelMA)-based bioinks mixed with different portions of alginate revealed bioprinted endothelium could be better modeled to optimize endothelial cell viability with a mixture of 7.5% GelMA and 2% alginate. Matrix stiffness plays a crucial role in modulating produced levels of Pro-Collagen I alpha-1 and matrix metalloproteinase-1 in human dermal fibroblasts and affecting their viability, proliferation, and spreading. Moreover, seeding human keratinocytes with gelatin-coating multiple times proved to be helpful in reducing culture time to create multiple layers of keratinocytes while maintaining their viability. The ability to fabricate selected biomaterials for each layer of skin tissues has implications in the biofabrication of skin systems for regenerative medicine and disease modeling. Center for Minimally Invasive Therapeutics (C-MIT) University of California-Los Angeles Bioprocess and Biotechnology Department Sãao Paulo State University (Unesp) School of Pharmaceutical Sciences, Km 01 Araraquara-Jau Road São Paulo State University (Unesp) Institute of Chemistry, 55 Prof. Francisco Degni Street Terasaki Institute for Biomedical Innovation Department of Bioengineering Henry Samueli School of Engineering and Applied Sciences University of California-Los Angeles Department of Electrical and Electronic Engineering The University of Hong Kong College of Pharmacy Kangwon National University U.S. Air Force Research Laboratory 711th Human Performance Wing Airman Systems Directorate Bioeffects Division Molecular Bioeffects Branch (USAFRL/711HPW/RHDJ) Department of Radiological Sciences University of California-Los Angeles Department of Biomedical Engineering Michigan State University Department of Chemical and Biomolecular Engineering Henry Samueli School of Engineering and Applied Sciences University of California-Los Angeles Jonsson Comprehensive Cancer Centre University of California Bioprocess and Biotechnology Department Sãao Paulo State University (Unesp) School of Pharmaceutical Sciences, Km 01 Araraquara-Jau Road São Paulo State University (Unesp) Institute of Chemistry, 55 Prof. Francisco Degni Street

Infectious keratitis is mainly treated with topical antibiotics. To achieve and maintain the required therapeutic concentration in the cornea where the tear fluid continuously rinses the surface, the antibiotics must be frequently applied, even while the patient is sleeping, and oral medication is sometimes required. However, the inevitably poor compliance and avascular nature of the cornea decrease drug bioavailability. In this study, a single microneedle (MN) is injected into the cornea to substitute for the repeated application of eyedrops in the treatment of infectious keratitis. After comparing the mechanical integrity and drug release profiles of three different drug-tips, the drug-tip with the "high" drug concentration that releases 12.5 ng drug within 3 days is applied to a cornea to evaluate the transferability and in vivo drug release. In the treatment of infectious keratitis with repeated application of eyedrops for six consecutive days, a single MN injection is substituted for the initial 3 days of eyedrop applications. The progression remains similarly attenuated after 3 days without eyedrops, and comparable efficacy is achieved on day 6 when combined with delayed eyedrop treatment from day 3. Thus, the single administration of a biodegradable MN can substitute for the repeated application of eyedrops in the treatment of infectious keratitis.

Engineering of biomimetic tissue implants provides an opportunity for repairing volumetric muscle loss (VML), beyond a tissue’s innate repair capacity. Here, we present thick, suturable, and pre-vascularized 3D muscle implants containing human induced pluripotent stem cell-derived myogenic precursor cells (hiPSC-MPCs), which can differentiate into skeletal muscle cells while maintaining a self-renewing pool. The formation of contractile myotubes and millimeter-long fibers from hiPSC-MPCs is achieved in chemically, mechanically, and structurally tailored extracellular matrix-based hydrogels, which can serve as scaffolds to ultimately organize the linear fusion of myoblasts. Embedded multi-material bioprinting is used to deposit complex patterns of perfusable vasculatures and aligned hiPSC-MPC channels within an endomysium-like supporting gel to recapitulate muscle architectural integrity in a facile yet highly rapid manner. Moreover, we demonstrate successful graft-host integration and de novo muscle formation upon in vivo implantation of pre-vascularized constructs within a VML model. This work pioneers the engineering of large pre-vascularized hiPSC-derived muscle tissues toward next generation VML regenerative therapies.

Elaborately and serially pH-modulated hydrogels possessing optimized viscoelastic natures for short gelation time and single syringe injection were designed for peritumoral injection of an anticancer agent. Boronate ester bonds between phenylboronic acid (PBA) (installed in HA-PBA (HP)) and dopamine (included in HA-dopamine (HD)) along with self-polymerization of dopamine (via interactions between HD conjugates) were introduced as the main cross-linking strategies of a hyaluronic acid (HA) hydrogel. Considering pKa values (8.0-9.5) of PBA and dopamine, the pH of each polymer dispersion was controlled elaborately for injection through a single syringe, and the final pH was tuned nearby the physiological pH (pH 7.8). The shear-thinning behavior, self-healing property, and single syringe injectability of a designed hydrogel cross-linked nearby physiological pH may provide its convenient application to peritumoral injection and prolonged retention in local cancer therapy. Erlotinib (ERT) was encapsulated in a microsphere (MS), and it was further embedded in an HP/HD-based hydrogel for sustained and locoregional delivery. A rheologically tuned hydrogel containing an ERT MS exhibited superior tumor-suppressive efficiencies compared to the other groups in A549 tumor-bearing mice. A designed injectable hydrogel through a single syringe system may be efficiently applied to local cancer therapy with lower toxicities to healthy organs.

Polypseudorotaxane structure and polydopamine bond-based crosslinked hyaluronic acid (HA) hydrogels including donepezil-loaded microspheres were developed for subcutaneous injection. Both dopamine and polyethylene glycol (PEG) were covalently bonded to the HA polymer for catechol polymerization and inclusion complexation with alpha-cyclodextrin (α-CD), respectively. A PEG chain of HA-dopamine-PEG (HD-PEG) conjugate was threaded with α-CD to make a polypseudorotaxane structure and its pH was adjusted to 8.5 for dopamine polymerization. Poly(lactic-co-glycolic acid) (PLGA)/donepezil microsphere (PDM) was embedded into the HD-PEG network for its sustained release. The HD-PEG/α-CD/PDM 8.5 hydrogel system exhibited an immediate gelation pattern, injectability through single syringe, self-healing ability, and shear-thinning behavior. Donepezil was released from the HD-PEG/α-CD/PDM 8.5 hydrogel in a sustained pattern. Following subcutaneous injection, the weight of excised HD-PEG/α-CD/PDM 8.5 hydrogel was higher than the other groups on day 14. These findings support the clinical feasibility of the HD-PEG/α-CD/PDM 8.5 hydrogel for subcutaneous injection.

Monopotassium phosphate and pH modulation-reinforced hydrogel based on hyaluronic acid (HA) grafted with dopamine (dopa) was fabricated as one of subcutaneous injection formulations of donepezil (DPZ). Both incorporation of KH2PO4 and pH adjustment finally attributed to tuning viscoelastic and biodegradable properties of hydrogel system. Appropriate gelation time for in situ gel formation, single syringe injectability, self-healing capability, and viscoelastic features were accomplished with the optimization of KH2PO4 concentration in hydrogel systems. DPZ base (as a poorly water soluble drug) was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) and it was further embedded in the hydrogel structure for sustained drug release. Biodegradability of designed KH2PO4-incorporated HA-dopa/DPZ MS hydrogel system was assessed by optical imaging and the remained gel weight of crosslinked HA-dopa hydrogel group was 3.4-fold higher than that of unmodified HA-dopa mixture group on day 14 (p

Stem cells secrete trophic factors that induce angiogenesis. These soluble factors are promising candidates for stem cell-based therapies, especially for cardiovascular diseases. Mechanical stimuli and biophysical factors presented in the stem cell microenvironment play important roles in guiding their behaviors. However, the complex interplay and precise role of these cues in directing pro-angiogenic signaling remain unclear. Here, a platform is designed using gelatin methacryloyl hydrogels with tunable rigidity and a dynamic mechanical compression bioreactor to evaluate the influence of matrix rigidity and mechanical stimuli on the secretion of pro-angiogenic factors from human mesenchymal stem cells (hMSCs). Cells cultured in matrices mimicking mechanical elasticity of bone tissues in vivo show elevated secretion of vascular endothelial growth factor (VEGF), one of representative signaling proteins promoting angiogenesis, as well as increased vascularization of human umbilical vein endothelial cells (HUVECs) with a supplement of conditioned media from hMSCs cultured across different conditions. When hMSCs are cultured in matrices stimulated with a range of cyclic compressions, increased VEGF secretion is observed with increasing mechanical strains, which is also in line with the enhanced tubulogenesis of HUVECs. Moreover, it is demonstrated that matrix stiffness and cyclic compression modulate secretion of pro-angiogenic molecules from hMSCs through yes-associated protein activity.

Injectable shear-thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varying compositions of gelatin and SNPs to navigate their material, mechanical, rheological, and bioactive properties. All compositions (each component percentage; 1.5-4.5%/total solid ranges; 3-9%) tested are injectable through both 5 Fr general catheter and 2.4 Fr microcatheter by manual pressure. In the results, an increase in gelatin contents causes decrease in swellability, increase in freeze-dried hydrogel scaffold porosity, increase in degradability and injection force during iSTB fabrication. Meanwhile, the amount of SNPs in composite hydrogels is mainly required to decrease degradability and increase shear thinning properties of iSTB. Finally, in vitro and in vivo biocompatibility tests show that the 1.5-4.5% range gelatin-SNP iSTBs are not toxic to the cells and animals. All results demonstrate that the iSTB can be modulated with specific properties for unmet clinical needs. Understanding of mechanical and biological consequences of the changing gelatin-SNP ratios through this study will shed light on the biomedical applications of iSTB on specific diseases.

Thrombosis is a life-threatening pathological condition in which blood clots form in blood vessels, obstructing or interfering with blood flow. Thrombolytic agents (TAs) are enzymes that can catalyze the conversion of plasminogen to plasmin to dissolve blood clots. The plasmin formed by TAs breaks down fibrin clots into soluble fibrin that finally dissolves thrombi. Several TAs have been developed to treat various thromboembolic diseases, such as pulmonary embolisms, acute myocardial infarction, deep vein thrombosis, and extensive coronary emboli. However, systemic TA administration can trigger non-specific activation that can increase the incidence of bleeding. Moreover, protein-based TAs are rapidly inactivated upon injection resulting in the need for large doses. To overcome these limitations, various types of nanocarriers have been introduced that enhance the pharmacokinetic effects by protecting the TA from the biological environment and targeting the release into coagulation. The nanocarriers show increasing half-life, reducing side effects, and improving overall TA efficacy. In this work, the recent advances in various types of TAs and nanocarriers are thoroughly reviewed. Various types of nanocarriers, including lipid-based, polymer-based, and metal-based nanoparticles are described, for the targeted delivery of TAs. This work also provides insights into issues related to the future of TA development and successful clinical translation.

International audience; Active biodegradable packaging films were developed with polyvinyl alcohol (PVA), chitosan (CS) and D-Limonene (DL). The effect of various DL content levels (0%, 2.5%, 5%, 7.5%, and 10% w/w) on the structural, mechanical, biodegradable and antimicrobial properties of PVA/CS films was systematically studied. Good compatibility between DL and PVA/CS, and good dispersion of DL in the PVA/CS matrix were demonstrated by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). PVA/CS films greatly improved their antibacterial, mechanical and barrier properties, which are associated with the considerable biodegradability, after they were incorporated with DL. However, the overloading with DL may weaken hydrogen bonds between polymer chains, resulting in the negative effects on the physical performances of the film. Particularly, the PVA/CS/DL-5% film showed the highest water contact angle and transmittance value, and also showed effective preservations of packaged mango fruits during 10 day of storage at 20 +/- 2 degrees C, based on the characterization by fruits weight loss, decay rate, firmness, titratable acidity, soluble solids, and ascorbic acid. Consequently, DL/PVA/CS composite films may be a promising eco-friendly packaging material for food preservation. (C) 2018 Published by Elsevier B.V.

Cell separation is a key step in many biomedical research areas including biotechnology, cancer research, regenerative medicine, and drug discovery. While conventional cell sorting approaches have led to high-efficiency sorting by exploiting the cell's specific properties, microfluidics has shown great promise in cell separation by exploiting different physical principles and using different properties of the cells. In particular, label-free cell separation techniques are highly recommended to minimize cell damage and avoid costly and labor-intensive steps of labeling molecular signatures of cells. In general, microfluidic-based cell sorting approaches can separate cells using "intrinsic" (e.g., fluid dynamic forces) versus "extrinsic" external forces (e.g., magnetic, electric field, etc.) and by using different properties of cells including size, density, deformability, shape, as well as electrical, magnetic, and compressibility/acoustic properties to select target cells from a heterogeneous cell population. In this work, principles and applications of the most commonly used label-free microfluidic-based cell separation methods are described. In particular, applications of microfluidic methods for the separation of circulating tumor cells, blood cells, immune cells, stem cells, and other biological cells are summarized. Computational approaches complementing such microfluidic methods are also explained. Finally, challenges and perspectives to further develop microfluidic-based cell separation methods are discussed.

Minimally invasive biosensors are emerging as powerful tools to enable personalized healthcare and precision medicine. Recent advances in biotechnology, wireless communication, and flexible electronics have offered unprecedented opportunity to develop minimally invasive biosensors for commercial applications. In this chapter, we discuss emerging technologies of minimally invasive biosensing and their working principle, applications, and challenges. We also present areas where further endeavors are needed and future directions in this field.

To treat retinal diseases, intravitreal injection is commonly performed to deliver therapeutic agents to the eye. However, intravitreal injection poses potential risks of ocular complications such as endophthalmitis, retinal detachment, and ocular hemorrhage. Thus, it is desired to develop a minimally invasive and therapeutically effective ocular drug delivery system without full penetration into the sclera. Here, we studied the possibility of precisely-controlled insertion of microneedles (MNs) into the sclera to different levels of depths and how different insertion depths could affect drug delivery into the sclera and to the back of the eye. A microneedle pen (MNP) was developed for depth-controlled scleral delivery by controlling insertion speeds, and it was confirmed that the insertion depths of MNs could be finely controlled by insertion speeds in ex vivo studies. Finite element modeling analyses were also conducted to understand how the depth-controlled insertion of MNs could significantly influence the diffusion distances of drug molecules. Finally, in vivo experiments demonstrated that this MNP system could be applied to the beagle eyes comparable to human ones for the scleral administration of therapeutic agents through the scleral tissues.

There are increasing demands for long-term and controlled corneal drug delivery to treat various ocular diseases. Although biodegradable ocular inserts or contact lenses have been developed, the invasiveness and inefficiency of the approaches still need to be improved. Microneedle (MN) technology can deliver therapeutic molecules to the eye in a minimally invasive manner. However, the current ocular MN technology is limited to either short-term corneal drug delivery or retinal drug delivery by suprachoroidal injection. For long-term and minimally invasive corneal drug delivery, we have developed a detachable biodegradable MN that can be delivered to the inside of the cornea for sustained drug release. The detachable and biodegradable MN is a hybrid MN consisting of a drug-loaded biodegradable tip and a supporting base. The hybrid MN can be applied to the cornea by impact insertion, and it leaves only the drug-loaded biodegradable tip within the corneal tissue so that it can release the drug for a certain period. By concentration-controlled molding, the dimension of drug-loaded MN tips was precisely controlled and their detachability was optimized. The detachable tip and a supporting base were assembled to form a hybrid MN by pressure-assisted transfer molding. We carefully optimized the dimension of the drug-tip, injection dwell time, and insertion depth to achieve effective intracorneal injection of the drug-tip. The detachable hybrid MN was applied to an Acanthamoeba keratitis model wherein a biodegradable drug-tip was successfully delivered to the inside of the mouse cornea in vivo. Follow-up of the MN-treated cases for 7 days confirmed the therapeutic efficacy of the detachable biodegradable MN tips. Statement of Significance For the treatment of infectious diseases in the cornea, such as keratitis, eye drops need to be applied topically every hour for a couple of days. This is extremely uncomfortable, and poor compliance to such tightly scheduled drug administration can result in permanent scar formation in the cornea. In this work, we demonstrate a simple and rapid injection of biodegradable microneedle tips in the corneal tissue wherein the tips can deliver antibacterial drugs for 4 days to treat keratitis. Unlike other patch-style microneedle technologies, this approach allows for insertion depth-controlled and highly localized injection of detachable individual microneedle tips to the diseased tissue for sustained drug delivery. This overcomes the limitations of patch-style microneedles such as short-term drug delivery and unnecessary blockage of tissue.

In this study, potassium persulfate, N,N'-methylene bisacrylamide (MBA), and soluble starch (ST) were in situ cross-linked into porous antimicrobial starch particles containing N-halamine functional groups (PST–MBA–Cl). Then, polyacrylonitrile (PAN)/silica aerogel (SA)/zinc oxide (ZnO) beaded fibers containing PST–MBA–Cl particles were prepared by electrospinning. Scanning electron microscopy results demonstrated the uniform dispersion of the PST–MBA–Cl particles and ZnO on the surface and interior of the beaded fiber when the concentration of the PST–MBA–Cl particles was 15%. The composite beaded fibers prepared after chlorination and soaking in zinc salt solutions of different pH values had a higher degree of interior fluffiness. For the analysis of the effectivity of the prepared particles using 108 CFU/mL gram-positive (S. aureus) and gram-negative (E. coli) bacterial human pathogens, the inhibition zone was 15.97 ± 0.12 and 17.81 ± 0.23 mm, respectively. Meanwhile, the degradation efficiency of PAN and SA for the cationic dye methylene blue (MB) was 88.00% ± 1.83%. The PAN/SA/PST–MBA–Cl/ZnO composite beaded fiber showed good antibacterial properties and a fast recovery rate, and its degradation efficiency for MB was retained at ~80% after five cycles. Thus, the PAN/SA/ PST–MBA–Cl/ZnO beaded fibers can be used as an environment-friendly and reusable adsorbing material for the removal of dyes from industrial wastewater.

In this study, we prepared a composite of chitosan (CS), halloysite nanotubes (HNTs), and tea polyphenols (TP) using 3D printing technology. The intermolecular interactions between the components and the printability of the ink were analyzed via Fourier transform infrared (FTIR) spectroscopy and rheological properties. The prepared CS/HNTs-TP composite container exhibited high fidelity and precision. The effects of printing parameters, such as nozzle diameter, air pressure, nozzle height, printing speed, and layer height, on the precision of printed CS/HNTs-TP composite containers were examined. The optimal parameters for printing 3D constructs were found to be 0.8-mm nozzle diameter, 0.4-MPa air pressure, 0.5-mm nozzle height, 30-mm/s printing speed, and 0.3-mm layer height, matching the target model with fine resolution, smooth surface texture, and high precision. The printed CS/HNTs-TP composite container was used for storing blueberries. After 12 days of storage, the blueberries preserved in the CS/HNTs-TP composite maintained a 41.87% weight loss ratio, a 59% decay rate, 9.1% total soluble solids (TSS), 4.1 N firmness, 0.43% titratable acidity (TA), and 14.27% ascorbic acid when compared with those of the control group and CS group. The results indicate that CS/ HNTs-TP composites are highly effective in maintaining the quality of blueberries.

Increasing evidence from cancer cell fusion with different cell types in the tumor microenvironment has suggested a probable mechanism for how metastasis-initiating cells could be generated in tumors. Although human mesenchymal stem cells (hMSCs) have been known as promising candidates to create hybrid cells with cancer cells, the role of hMSCs in fusion with cancer cells is still controversial. Here, we fabricated a liver-on-a-chip platform to monitor the fusion of liver hepatocellular cells (HepG2) with hMSCs and study their invasive potential. We demonstrated that hMSCs might play dual roles in HepG2 spheroids. The analysis of tumor growth with different fractions of hMSCs in HepG2 spheroids revealed hMSCs’ role in preventing HepG2 growth and proliferation, while the hMSCs presented in the HepG2 spheroids led to the generation of HepG2-hMSC hybrid cells with much higher invasiveness compared to HepG2. These invasive HepG2-hMSC hybrid cells expressed high levels of markers associated with stemness, proliferation, epithelial to mesenchymal transition, and matrix deposition, which corresponded to the expression of these markers for hMSCs escaping from hMSC spheroids. In addition, these fused cells were responsible for collective invasion following HepG2 by depositing Collagen I and Fibronectin in their surrounding microenvironment. Furthermore, we showed that hepatic stellate cells (HSCs) could also be fused with HepG2, and the HepG2-HSC hybrid cells possessed similar features to those from HepG2-hMSC fusion. This fusion of HepG2 with liver-resident HSCs may propose a new potential mechanism of hepatic cancer metastasis.

The physiological and toxicological evaluation of nano-silicon dioxide (nano-SiO2) particles in food is important for ensuring food safety. In this study, nano-SiO2 particles isolated from five brands of instant coffee, were structurally characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential analyses. Their toxicity was assessed by measuring cell viability, membrane integrity, and reactive oxygen species (ROS) levels in model gastrointestinal cells (GES-1 and Caco-2). Additionally, mortality, deformity rate, heart rate and death of whole zebra fish embryos were measured. The five types of nano-SiO2 samples comprised amorphous particles with a purity of approximately 99%, which met the food additive standard. Considering that the original particle size ranged from 10 to 50 nm, the samples were classified as nano-SiO2 food additives. Nano-SiO2 did not significantly impact the activity of GES-1 or Caco-2 cells, and no significant cell membrane damage was observed (Caco-2 cells exhibited mild micro damage); however, a slight increase in intracellular RPS levels was detected. Moreover, nano-SiO2 was found to cause head deformity, pericardial edema, yolk sac edema and tail bending. Collectively, the results show that nano-SiO2 time- and dose-dependently affects GES-1 and Caco-2 cell viability, as well as the mortality, heart rate, and abnormality rate of zebra fish embryos. Specifically, a high concentration (≥ 200 μg/mL) and long exposure time (≥ 48 h) of food additive nano-SiO2 affected GES-1, Caco-2 cells, and the gastrointestinal tract in zebra fish embryos.

Polyvinyl alcohol (PVA)/titanium dioxide nanoparticles (TiO2 NPs)/3,3′,4,4′-Benzophenone tetracarboxylic acid (BPTA) antibacterial films were prepared by solvent casting and chemical grafting using PVA as the base material and TiO2 NPs and BPTA as antibacterial materials. Scanning electron microscopy results showed that the distribution of TiO2 NPs inside the polymer matrix was substantially uniform. X-ray diffraction (XRD) and FTIR-ATR spectroscopy were used to demonstrate the successful embedding of NPs and the formation of ester bonds in the grafting process, respectively. In the antibacterial experiment, the PVA/1%TiO2 NPs/BPTA film exhibited higher antibacterial activity than other films. Compared with the control group, the surviving population of S. aureus and E. coli decreased by 99.62 ± 0.38% and 98.27 ± 1.47%, respectively. The mechanism of reactive oxygen species (ROS) production was discussed, and the amount of ROS produced by the composite films under light and dark conditions was quantitatively measured. A cycling experiment after quenching ROS showed that the PVA/1%TiO2 NPs/BPTA composite film retained 81.01% and 66.12% of the original charging capacity of the OH• radical and H2O2 after seven cycles. In terms of biodegradability, the degradation performance of the PVA/TiO2 NPs/BPTA composite film was stronger than that of the pure PVA film. Thus, the PVA/TiO2 NPs/BPTA film is considered a promising antibacterial material with superior characteristics of structural stability, reusability, and functionality under both light and dark conditions.

After surgical procedures such as coronary/peripheral bypass grafting or endarterectomy for the treatment of organ ischemia derived from atherosclerosis, intimal hyperplasia (IH) which leads to restenosis or occlusion at the site of graft anastomosis frequently occurs. In order to inhibit IH caused by abnormal growth of smooth muscle cells (SMCs) in tunica media, various perivascular drug delivery devices are reported for delivery of anti-proliferation drugs into vascular tissue. However, there still remain conflicting requirements such as local and unidirectional delivery vs device porosity, and conformal tight device installation vs pulsatile expansion and constriction of blood vessels. In this study, a biodegradable microneedle (MN) array is developed on a flexible woven surgical mesh using a transfer molding method. Mechanical properties of 'wrappable' MN meshes are investigated and compared to the properties of blood vessels. Ex vivo and in vivo animal studies demonstrate enhanced drug delivery efficiency, efficacy for IH reduction, and safety of MN mesh. In particular, MN mesh showed significantly reduced neointiamal formation (11.1%) compared to other competitive groups (23.7 and 22.2%) after 4-week in vivo animal study. Additionally, wrappable MN meshes effectively suppressed side effects such as IH due to mechanical constriction, loss of toxic drug to the surroundings, and cell death that were frequently observed with other previous perivascular drug delivery devices.

Microneedles (MNs) have been used to deliver drugs for over two decades. These platforms have been proven to increase transdermal drug delivery efficiency dramatically by penetrating restrictive tissue barriers in a minimally invasive manner. While much of the early development of MNs focused on transdermal drug delivery, this technology can be applied to a variety of other non-transdermal biomedical applications. Several variations, such as multi-layer or hollow MNs, have been developed to cater to the needs of specific applications. The heterogeneity in the design of MNs has demanded similar variety in their fabrication methods; the most common methods include micromolding and drawing lithography. Numerous materials have been explored for MN fabrication which range from biocompatible ceramics and metals to natural and synthetic biodegradable polymers. Recent advances in MN engineering have diversified MNs to include unique shapes, materials, and mechanical properties that can be tailored for organ-specific applications. In this review, we discuss the design and creation of modern MNs that aim to surpass the biological barriers of non-transdermal drug delivery in ocular, vascular, oral, and mucosal tissue.

High rates of restenosis and neointimal formation have driven increasing interest in the application of drug eluting balloons (DEB) as counteractive measures for intraluminal drug delivery. The use of DEBs eliminates the need for stents so that serious side effects including in-stent restenosis and stent thrombosis can be avoided and long-term medication of anti-platelet agent is not needed. Despite their benefits, DEBs have poor drug delivery efficiency due to short balloon inflation times (30–60 s) that limit the passive drug diffusion from the balloon surface to the luminal lesion. To increase drug delivery efficiency, a microneedle DEB (MNDEB) was developed by a conformal transfer molding process using a thin polydimethylsiloxane mold bearing a negative array of MNs of 200 μm in height. A MN array composed of UV curable resin was formed onto the surface of DEB, and drugs were coated onto the structure. The mechanical properties of the MN array were investigated and MN penetration into luminal vasculature was confirmed in vivo. An increase in drug delivery efficiency compared to a standard DEB was demonstrated in an in vivo test in a rabbit aorta. Finally, the superior therapeutic efficacy of MNDEBs was evaluated using an atherosclerosis rabbit model.

Multicomponent biomaterials using a high-throughput system regulate hyaline or hypertrophic chondrogenesis of hMSCs., Despite great progress in biomaterial design strategies for replacing damaged articular cartilage, prevention of stem cell-derived chondrocyte hypertrophy and resulting inferior tissue formation is still a critical challenge. Here, by using engineered biomaterials and a high-throughput system for screening of combinatorial cues in cartilage microenvironments, we demonstrate that biomaterial cross-linking density that regulates matrix degradation and stiffness—together with defined presentation of growth factors, mechanical stimulation, and arginine-glycine-aspartic acid (RGD) peptides—can guide human mesenchymal stem cell (hMSC) differentiation into articular or hypertrophic cartilage phenotypes. Faster-degrading, soft matrices promoted articular cartilage tissue formation of hMSCs by inducing their proliferation and maturation, while slower-degrading, stiff matrices promoted cells to differentiate into hypertrophic chondrocytes through Yes-associated protein (YAP)–dependent mechanotransduction. in vitro and in vivo chondrogenesis studies also suggest that down-regulation of the Wingless and INT-1 (WNT) signaling pathway is required for better quality articular cartilage-like tissue production.

Three-dimensional (3D) printing technology has received great attention in the past decades in both academia and industry because of its advantages such as customized fabrication, low manufacturing cost, unprecedented capability for complex geometry, and short fabrication period. 3D printing of metals with controllable structures represents a state-of-the-art technology that enables the development of metallic implants for biomedical applications. This review discusses currently existing 3D printing techniques and their applications in developing metallic medical implants and devices. Perspective about the current challenges and future directions for development of this technology is also presented. Keywords: 3D printing, Biometals, Biocompatibility, Medical devices, Clinical application

The liver possesses a unique microenvironment with a complex internal vascular system and cell-cell interactions. Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease, and although much effort has been dedicated to building models to target NAFLD, most in vitro systems rely on simple models failing to recapitulate complex liver functions. Here, an in vitro system is presented to study NAFLD (steatosis) by coculturing human hepatocellular carcinoma (HepG2) cells and umbilical vein endothelial cells (HUVECs) into spheroids. Analysis of colocalization of HepG2-HUVECs along with the level of steatosis reveals that the NAFLD pathogenesis could be better modeled when 20% of HUVECs are presented in HepG2 spheroids. Spheroids with fat supplements progressed to the steatosis stage on day 2, which could be maintained for more than a week without being harmful for cells. Transferring spheroids onto a chip system with an array of interconnected hexagonal microwells proves helpful for monitoring functionality through increased albumin secretions with HepG2-HUVEC interactions and elevated production of reactive oxygen species for steatotic spheroids. The reversibility of steatosis is demonstrated by simply stopping fat-based diet or by antisteatotic drug administration, the latter showing a faster return of intracellular lipid levels to the basal level.