Increase In Adhesion Force Research Articles

Optimizing Subretinal Bleb Formation for Visual Streak Involvement in a Porcine Model for Retinal Gene Therapy.

Subretinal (SR) injection in porcine models is a promising avenue for preclinical evaluation of cell and gene therapies. Targeting of the subretinal fluid compartment (bleb) is critical to the procedure, especially if treatment of the cone-rich area centralis is required (i.e., visual streak [VS] in pigs). To our knowledge, this study is the first to investigate the influence of injection site placement on VS involvement in the pig eye. We performed 23-gauge pars plana vitrectomy followed by SR injection in 41 eyes of 21 animals (Sus scrofa domesticus). In 27 eyes (65.9%), the injection site was placed superior to the VS, and in 14 eyes (34.1%) it was placed inferior to it. Using intraoperative imaging, blebs were classified based on their propagation behavior relative to the VS. In 79% of cases, blebs from inferior injection sites developed away from the VS, exhibiting a mean ± SEM vertical anisotropy (AP) of 0.67 ± 0.11. In contrast, blebs from superior injection sites tended to develop toward the VS with an AP of 1.27 ± 0.18 (P = 0.0070). Blebs developed away from the VS in only 41% of injections (P = 0.0212). Inferior blebs were orientated close to 0° (horizontal), whereas superior blebs displayed varied orientations with a mean angle of 56° (P = 0.0008). Bleb propagation was anisotropic (i.e., directionally biased) and dependent on injection site placement. Superior injection sites led to superior VS detachment. Morphological analysis suggested increased adhesion forces at the VS and superior vascular arcades. This study will aid the planning of surgeries for targeted subretinal delivery in pig models.

Zinc and copper effect mechanical cell adhesion properties of the amyloid precursor protein.

The amyloid precursor protein (APP) can be modulated by the binding of copper and zinc ions. Both ions bind with low nanomolar affinities to both subdomains (E1and E2) in the extracellular domain of APP. However, the impact of ion binding on structural and mechanical trans-dimerization properties is yet unclear. Using a bead aggregation assay (BAA), we found that zinc ions increase the dimerization of both subdomains, while copper promotes only dimerization of the E1 domain. In line with this, scanning force spectroscopy (SFS) analysis revealed an increase in APP adhesion force up to three-fold for copper and zinc. Interestingly, however, copper did not alter the separation length of APP dimers, whereas high zinc concentrations caused alterations in the structural features and a decrease of separation length. Together, our data provide clear differences in copper and zinc mediated APP trans-dimerization and indicate that zinc binding might favor a less flexible APP structure. This fact is of significant interest since changes in zinc and copper ion homeostasis are observed in Alzheimer's disease (AD) and were reported to affect synaptic plasticity. Thus, modulation of APP trans-dimerization by copper and zinc could contribute to early synaptic instability in AD.

Mussel-inspired biomimetic modification to enhance adhesion properties between granite and asphalt: Multi-scales characterizations and molecular mechanisms

Mussel-inspired biomimetic modifiers and amine surface modifiers were used to biomimetic modify granite surface to improve adhesion properties of granite with asphalt. Adhesion properties of granite were characterized at multi-scales, where the fire-scouring effect during hot mixing on adhesion properties of surface modified granite was considered. Meanwhile, adhesion mechanism between surface modified granite and asphalt was explored based on molecular simulation. The results of study were as follows: (1) Mussel-inspired biomimetic surface modification of granite could significantly enhance adhesion properties of granite with asphalt, as demonstrated by 115.59 % increase in tensile fracture strength, 81.18 % increase in surface energy, and 82.77 % increase in adhesion force. (2) Mussel-inspired surface biomimetic modification of granite had better resistance fire-scorching effect. Adhesion properties of surface modification by SCA after fire-scorching decreased by 18.51 %, 34.14 %, and 20.07 % at multi-scales, while adhesion properties of mussel-inspired biomimetic modification after fire-scouring decreased by 14.29 %, 9.14 %, and 12.27 % at multi-scales. (3) Molecular simulations showed that surface modified granite could enhance adhesion properties not only by increasing electrostatic interactions, but also by improving granite-asphalt interaction and attracting heavy components of asphalt to rearrangement. Among them, polarity adhesion induced by mussel-inspired biomimetic modification plays dominant role in enhancing adhesion properties.

Mrlac1, an extracellular laccase, is required for conidial morphogenesis as well as the well adaptability in field of Metarhizium rileyi

Acting as an extremely promising fungal pesticide, Metarhizium rileyi exhibits robust insecticidal activity against Lepidoptera pests, particularly the larvae. Though there is a slight delay in efficacy, biopesticides offer salient advantages over traditional chemical pesticide especially in environmental safety, cyclic infection and resistant inhibition. In this study, an exterior T-DNA was randomly inserted into the genome of M. rileyi, resulting in the acquisition of a mutant strain that displayed a colour transition from green to yellow within its conidia. The disruption of Mrlac1, a laccase, has been confirmed to attribute to the epigenetic alterations. Mrlac1 is a secreted protein harboring an N-terminal signaling peptide that undergoes in vivo synthesis and accumulates on the cell wall of M. rileyi. Targeted knock-out mutant exhibited alterations not just in conidia coloration, but significantly diminished capacity to withstand external stressors, particularly non-biological factors such as high humidity, Congo red exposure, and UV radiation. The disruptant suffered a constraint on hyphal polar growth, alteration in conidial surface structure, as well as noticeable increase in adhesion forces between conidia, the core infection factors. There is a remarkable diminution in virulence of Mrlac1 deletion variant against larvae of Spodoptera litura by topical inoculation, but not hemolymph injection. Our findings suggest that Mrlac1 acts as a positive regulator in the normal morphogenesis of fungal conidia, encompassing pigment production, inter-conidia adhesion, and conidial cell wall integrity, while the preservation of these structures holds paramount importance for the survival and infection of M. rileyi in the field.

Comparison of contact time dependence of adhesion force between silica/DLC and silica/graphene interfaces by AFM at different humidities

Abstract Understanding adhesion mechanisms is one way to address failures in micro-nano devices. In this paper, the adhesion forces of diamond-like carbon film (DLC) and graphene were measured, and the differences between them were compared. The results show that the adhesion forces on the DLC are dependent on the contact time, but this dependence is disrupted by repeated contacts. The impact of repeated contacts is inevitable. With the increase of repeated contacts, the size of the liquid bridge was changed, and the time to reach saturation became shorter. Finally, at low relative humidity (RH), the adhesion behaviors become independent. In contrast, the adhesion forces of graphene had no contact time dependence under each RH. The adhesion forces remained stable at low and medium RH, and the influence of repeated contacts was weak. At high RH, a sudden increase in adhesion forces caused by repeated contacts can be observed. The adhesion behaviors under different RHs are attributed to the size change of the liquid bridge. The results help people understand the adhesion mechanisms and provide some help in solving the failure problem of micro-nano devices.

Nature-inspired parylene/SiO2 core-shell micro-nano pillars: Effect of topography and surface chemistry

We investigated the synergy of surface topography and chemistry in micro/nanostructured pillars inspired by nature, specifically mimicking tokay gecko (Gekko gecko Linnaeus, 1758) feet and sacred lotus (Nelumbo nucifera Gaertn., 1788) leaves. The aim is to understand and replicate their adhesive and self-cleaning properties for diverse applications. Through a detailed fabrication process and chemical modifications, the surfaces exhibit superhydrophobic characteristics. The research precisely examines the fabrication of surfaces with well-defined micropillars using lithography and deep silicon substrate etching. Diverse surface treatments, including silanization and O2 plasma, are applied to tailor the chemical composition of microstructured surfaces. Utilizing a ≈ 5 nm thin SiO2 interface layer, the study reveals superhydrophobic properties post-silanization and an eightfold increase in adhesion force (FA) between the studied surface and reference surfaces. FA measurements using atomic force microscopy reveal an eightfold increase in adhesion on both flat and microstructured surfaces, emphasizing the transformative effects of microstructures on surface morphology. The findings highlight the potential for multifunctional surface designs, elucidating that superhydrophobic properties correlate with structure topography while FA amplitude is predominantly determined by surface termination. Inspired by nature, this research unveils novel possibilities in functional materials and surface engineering, with broad implications across various applications.

Single-cell fluid-based force spectroscopy reveals near lipid size nano-topography effects on neural cell adhesion.

Nano-roughness has shown great potential in enhancing high-fidelity electrogenic cell interfaces, owing to its characteristic topography comparable to proteins and lipids, which influences a wide range of cellular mechanical responses. Gaining a comprehensive understanding of how cells respond to nano-roughness at the single-cell level is not only imperative for implanted devices but also essential for tissue regeneration and interaction with complex biomaterial surfaces. In this study, we quantify cell adhesion and biomechanics of single cells to nano-roughened surfaces by measuring neural cell adhesion and biomechanics via fluidic-based single-cell force spectroscopy (SCFS). For this, we introduce nanoscale topographical features on polyimide (PI) surfaces achieving roughness up to 25 nm without chemical modifications. Initial adhesion experiments show cell-specific response to nano-roughness for neuroblastoma cells (SH-SY5Y) compared to human astrocytes (NHA) around 15 and 20 nm surface roughness. In addition, our SCFS measurements revealed a remarkable 2.5-fold increase in adhesion forces (150-164 nN) for SH-SY5Y cells cultured on roughened PI (rPI) surfaces compared to smooth surfaces (60-107 nN). Our data also shows that cells can distinguish changes in nano-roughness as small 2 nm (close to the diameter of a single lipid) and show roughness dependence adhesion while favoring 15 nm. Notably, this enhanced adhesion is accompanied by increased cell elongation upon cell detachment without any significant differences in cell area spreading. The study provides valuable insights into the interplay between nano-topography and cellular responses and offers practical implications for designing biomaterial surfaces with enhanced cellular interactions.

Ag2O-Containing Biocidal Interpolyelectrolyte Complexes on Glass Surfaces-Adhesive Properties of the Coatings.

Biocidal coatings are of great interest to the healthcare system. In this work, the biocidal activity of coatings based on a complex biocide containing polymer and inorganic active antibacterial components was studied. Silver oxide was distributed in a matrix of a positively charged interpolyelectrolyte complex (IPEC) of polydiallyldimethylammonium chloride (PDADMAC) and sodium polystyrene sulfonate (PSS) using ultrasonic dispersion, forming nanoparticles with an average size of 5-6 nm. The formed nanoparticles in the matrix are not subject to agglomeration and changes in morphology during storage. It was found that the inclusion of silver oxide in a positively charged IPEC allows a more than 4-fold increase in the effectiveness of the complex biocide against E. coli K12 in comparison with the biocidal effect of PDADMAC and IPEC. Polycation, IPEC, and the IPEC/Ag2O ternary complex form coatings on the glass surface due to electrostatic adsorption. Adhesive and cohesive forces in the resulting coatings were studied with micron-scale coatings using dynamometry. It was found that the stability of the coating is determined primarily by adhesive interactions. At the macro level, it is not possible to reliably identify the role of IPEC formation in adhesion. On the other hand, use of the optical tweezers method makes it possible to analyze macromolecules at the submicron scale and to evaluate the multiple increase in adhesive forces when forming a coating from IPEC compared to coatings from PDADMAC. Thus, the application of ternary IPEC/Ag2O complexes makes it possible to obtain coatings with increased antibacterial action and improved adhesive characteristics.

Insights into the effect of ethyl xanthate on the adhesion and biofilm formation by Acidianus manzaensis on chalcopyrite

Adhesion and biofilm formation play important roles in the bio-dissolution of metal sulfides, which can initiate dissolution and enhance bioleaching. Ethyl xanthate, a commonly used flotation reagent, remained in flotation concentrates of metal sulfides and may have an impact on the bioleaching of metal sulfides. Therefore, it is important to analyze the effect of ethyl xanthate on microbial initial adhesion and biofilm formation. The results showed that the adhesion percentage of Acidianus manzaensis on chalcopyrite decreased with increasing ethyl xanthate concentration after adsorption equilibrium, due to the toxicity of ethyl xanthate to A. manzaensis. However, a low concentration (0.01 mg/L) of ethyl xanthate had little effect on the growth of A. manzaensis. The hydrophobicity of chalcopyrite increased after the addition of ethyl xanthate, leading to an increase in total interaction energy and adhesion force. The presence of ethyl xanthate inhibited the early growth of biofilm and delayed the formation of microcolonies on chalcopyrite. While biofilm coverage was larger with the addition of ethyl xanthate than that of the control when biofilm was mature. Furthermore, in the presence of ethyl xanthate, more and larger microcolonies were observed on the chalcopyrite surface when biofilm was matured, resulting in an increased corrosion degree and more jarosite produced on the chalcopyrite surface. This study suggested that a low concentration (0.01 mg/L) of ethyl xanthate could promote the dissolution of chalcopyrite, which could be significant for bioleaching of flotation reagent-bearing flotation concentrates.

Improvement of the durability of concrete by substitution of raw ground colemanite

This study investigated the effects of raw ground colemanite (GC) mineral on concrete strength and durability. Concrete mixtures were prepared at six replacement levels of GC (0%, 1%, 2%, 3%, 4% and 5%, by weight of cement). Fresh state properties of concrete samples were measured. Schmidt Hammer, ultrasound pulse velocity, abrasion, flexural, and compressive strength tests were performed on the cube, cylinder and prismatic concrete samples on the 7th, 28th, and 90th days. As concrete durability has a negative impact on many physical and chemical factors, the durability properties of the samples after wet-dry, freeze-thaw, sulphate, and chloride exposure were investigated, resulting in the finding that GC substitution up to 5% yields the desired compressive strength for the C30/37 concrete class. The optimal GC substitution ratio was determined to be 3%, as this ratio increases the strength and durability probabilities. It was decided that raw GC mineral substitution with an average particle size of 12 µm and increasing adhesion force in concrete production is convenient, particularly in the context of improving material properties against environmental circumstances, saving cement, and utilizing boron minerals.

Mussel-inspired anti-permeation hybrid sunscreen with reinforced UV-blocking and safety performance

Sun protection has gradually become an indispensable living habit of human beings, and sunscreens are needed under various circumstances. Considering the disadvantages and abuse of traditional sunscreen additives which are proved to have some potential threats to human body and natural environment, it is an urgent need to develop new sunscreens with both safety and high efficiency for the evolution of the industry. Therefore, as a complement to the shortcomings, polydopamine (PDA) was hybridized with zinc oxide (ZnO) by a simple sol-gel method. The obtained novel sunscreen agent had high ultraviolet (UV) resistance efficiency, as the SPF (∼77.2) and PA (PA+++) value at only 10 wt% addition could meet the daily sunscreen requirements. Besides, the permeation of ZnO and Zn2+ could be almost completely avoided through the epidermis layer of skin, due to the increase of mussel-inspired adhesive force. Furthermore, the free radical scavenging rate could reach 88.1% at low concentration, and it was proved to have no cytotoxicity. Overall, the ZnO-PDA has a good application prospect in high-efficiency and safe sunscreen, and it can be an impetus for the development of novel cosmetics.

Process and Drying Behavior Toward Higher Drying Rates of Hard Carbon Anodes for Sodium‐Ion Batteries with Different Particle Sizes: An Experimental Study in Comparison to Graphite for Lithium‐Ion‐Batteries

Sodium‐ion batteries are considered to be one of the most promising postlithium batteries on the verge of commercialization. The electrode processing is expected to be similar to lithium‐ion batteries. However, the producibility and material processing challenges of potential electrode materials for anodes and cathodes are poorly understood. For industrial electrode production, a deep understanding of the processing of electrode materials with different particle morphologies is of great importance. In particular, the correlation between the process conditions and the electrode properties needs to be investigated further to understand the complex interactions between the battery slurry materials, the binder system, the drying process, and the microstructure formation. One promising anode material is hard carbon. The water‐based processing of hard carbon slurries presented in this article shows that the drying behavior is strongly interconnected with the particle size and particle interactions in the drying electrode. This study shows that all the hard carbons investigated do not exhibit binder migration at moderate drying rates. Even at very high drying rates (9 g m−2 s−1, 12 s drying time), an increase in adhesion force of up to 39% is observed for comparatively smaller particles compared to the adhesion force at lower drying rate.

Interfacial adhesion strength between FDM-printed PLA parts and surface-treated cellulosic-woven fabrics

PurposeThe purpose of this study is to investigate surface treatments and fiber types on adhesion properties polylactic acid (PLA) three-dimensional (3D) parts printed on woven fabrics.Design/methodology/approachThe cotton, flax and jute fabrics were exposed to alkali, hydrogen peroxide, stearic acid and ionic liquid treatments to modify surface characteristics before PLA 3D printing. The modification efficiency was assessed with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyses. Then, fused deposition modeling (FDM) printer and PLA filament were used for 3D printing onto the untreated and treated fabrics. The adhesion strength between the fabrics and PLA 3D parts were tested according to DIN 53530 via universal tensile tester.FindingsThe fabric structure is effective on adhesion force and greater values were observed for plain weave fabrics. Maximum separation forces were obtained for alkali pretreated fabrics among jute and cotton. Hydrogen peroxide treatment also increased adhesion forces for jute and cotton fabrics while decreasing for flax fabrics. Stearic acid and ionic liquid treatments reduced adhesion forces compared to untreated fabrics. Treatments are effective to alter adhesion via changing surface chemistry, surface morphology and fabric physical properties but display different effects related to fabric material.Originality/valueThis study provides experimental information about effects of different fiber types and surface treatments on adhesion strength of PLA 3D parts. There is limited research about comprehensive observation on 3D printing on cellulosic-woven fabrics.

Effects of solvent vapor annealing on the optical properties and surface adhesion of conjugated D : A thin films.

A diketopyrrolopyrrole (DPP) and perylene diimide (PDI)-based molecule, denoted as PDI-DPP-PDI, was investigated as an electron acceptor material in bulk heterojunction (BHJ) solar cells, with poly[[4,8-bis [5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [2-(2-ethyl-1-oxohexyl)thieno[3,4-b]thiophenediyl]] (PBDTTT-CT) as an electron donor. The donor polymer and the acceptor molecule have complementary absorption spectra, which is an essential feature for energy collection in organic solar cells. However, AFM images indicated the presence of isolated and microsized PDI-DPP-PDI domains along the surface of the films, which reduced the power conversion efficiency. Therefore, to improve the homogenization of the acceptor along the film, a post-deposition treatment, denoted as solvent vapor annealing (SVA), was performed in a saturated atmosphere containing the vapour of an organic solvent for 3-10 minutes. This procedure changed the optical and morphological properties of the PBDTTT-CT : PDI-DPP-PDI active layer, resulting in increased power conversion efficiency values by more than 2.5 times (reaching 5.1%). Theoretical simulation pointed out that the experimental absorbance band localized at 580 nm, which appeared after SVA treatment, is possibly related to an intense simulated band with a maximum at 572 nm, resulting from a pair of transitions starting in the copolymer and ending in PDI-DPP-PDI, in regions where both are stacked at about 3 Å. The most significant natural transition orbitals (NTOs) related to these transitions indicated charge transfer character. Moreover, analyses carried out by power spectrum density (PDS) of images acquired from the SVA-treated film indicated that in the region of larger frequencies, across the length scale at around 30-70 nm, an additional fractal region appeared with a Ds of 0.95, indicating a flattened region, possibly related to changes in the overall conformation after SVA treatment. This indicates an improvement in the molecular packing, a feature not observed in the as-cast film. The analyses by force curve spectroscopy pointed out increased adhesion forces and adhesion energy in the PBDTTT-CT : PDI-DPP-PDI film after SVA treatment; this feature enhanced the interfacial interaction with the top electrodes, reflecting improved charge extraction in the photovoltaic device.

Optical manipulation: from fluid to solid domains

Light carries energy and momentum, laying the physical foundation of optical manipulation that has facilitated advances in myriad scientific disciplines, ranging from biochemistry and robotics to quantum physics. Utilizing the momentum of light, optical tweezers have exemplified elegant light–matter interactions in which mechanical and optical momenta can be interchanged, whose effects are the most pronounced on micro and nano objects in fluid suspensions. In solid domains, the same momentum transfer becomes futile in the face of dramatically increased adhesion force. Effective implementation of optical manipulation should thereupon switch to the “energy” channel by involving auxiliary physical fields, which also coincides with the irresistible trend of enriching actuation mechanisms beyond sole reliance on light-momentum-based optical force. From this perspective, this review covers the developments of optical manipulation in schemes of both momentum and energy transfer, and we have correspondingly selected representative techniques to present. Theoretical analyses are provided at the beginning of this review followed by experimental embodiments, with special emphasis on the contrast between mechanisms and the practical realization of optical manipulation in fluid and solid domains.

Effect of different levels of green banana flour, chia seeds, sugar, cocoa powder and eggs on textural, physical and sensory properties of chocolate cake

The development of healthier and tasty chocolate cakes with substitution of traditional ingredients by functional ingredients is still a challenge for the food industry. The aim of this study was to evaluate the physicochemical and sensory characteristics of chocolate cakes made with two different concentrations of green banana flour (GBF) + wheat flour (WF) and hydrated chia + fat, sugar, cocoa powder and eggs by using the Plackett-Burman experimental design (PB12). It was observed that a decrease in WF, GBF and sugar resulted in an increase of water activity, volume and adhesion force. Moreover, an increase in WF, GBF, egg, chia, and sugar resulted in an increase on firmness, elasticity and crust colour. The scanning electron microscopy showed a porous and weak structure for formulations with GBF and chia seeds. The highest scores for the overall acceptability were found for formulations with 75% of GBF in replacement of WF and 50% of chia seeds as fat substitution agent associated with low levels of eggs, sugar and cocoa powder. These results indicate the potential use of chia seeds and GBF in combination to manufacture healthier chocolate cakes.

Nano-Capillary Bridges Control the Adhesion of Ice: Implications for Anti-Icing via Superhydrophobic Coatings

Understanding the ice adhesion mechanism is vital for efficient anti-icing. However, previous studies focused on the adhesion of already sintered ice-solid contacts. Here, we study the adhesion mechanism between preformed ice and solid surfaces. In particular, we investigate the initial stages of ice adhesion. We find that capillary bridges formed by the quasi-liquid layer on the ice surface enhance ice adhesion. The adhesion force showed a maximum around −2 °C. Our model indicates that the nano-scaled curvature of the capillary bridge gives rise to strong adhesion forces in the temperatures between −5 and 0 °C. The capillary bridge expands and consolidates over time, causing an increase of adhesion force. These findings provide new physical insights into the ice adhesion mechanism with strong implications to the development of water-repellent superhydrophobic coatings for efficient anti-icing of solid surfaces.

Effect of X-ray exposure on nano-mechanical properties of multi-walled carbon nanotube incorporated silicone polymer nanocomposites: An AFM-based study

Nano-mechanical properties of silicone polymer-based nanocomposites loaded with multi-walled carbon nanotube (MWCNT) as nanofillers are probed here using the atomic force microscopy (AFM) technique. Further, the effects of MWCNT concentration and X-ray exposure on the nano-mechanical and topographic properties of the polymer nanocomposites are systematically studied. The root mean square surface roughness is found to increase by ∼123% when the neat polymer matrix is loaded with 2.5 wt.% of MWCNT, whereas, for a fixed MWCNT concentration, the surface roughness is found to increase by ∼171% after X-ray irradiation. This is attributed to the X-ray induced polymer degradation, polymer pull-out and poor filler-matrix interaction leading to the aggregation of MWCNT. Adhesion force and adhesion energy are estimated from the AFM-based force-displacement curves. Both quantities are found to increase with MWCNT concentration. After an exposure to diagnostic X-rays (30–70 keV), the adhesion force is found to increase by ∼4 times, which is attributed to the increased tip-surface contact area due to the higher surface roughness of the X-ray exposed samples. Further, the variation of adhesion energy with filler concentration is found to be in agreement with the theoretical values obtained from the Johnson, Kendall and Roberts (JKR) model. The elastic modulus is found to increase with the filler concentration due to an increase in adhesion force. The obtained results are beneficial for the optimal design of nanofiller loaded polymer nanocomposites for various applications, including the fabrication of lead-free radio-opaque nanocomposites.

Adhesion of LHRH/EphA2 to human Triple Negative Breast Cancer tissues

The adhesive interactions between molecular recognition units (such as specific peptides and antibodies) and antigens or other receptors on the surfaces of tumors are of great value in the design of targeted nanoparticles and drugs for the detection and treatment of specific cancers. In this paper, we present the results of a combined experimental and theoretical study of the adhesion between Luteinizing Hormone Releasing Hormone (LHRH)/Epherin type A2 (EphA2)–AFM coated tips and LHRH/EphA2 receptors that are overexpressed on the surfaces of human Triple Negative Breast Cancer (TNBC) tissues of different histological grades. Following a histochemical and immuno-histological study of human tissue extracts, the receptor overexpression, and their distributions are characterized using Immunohistochemistry (IHC), Immunofluorescence (IF), and a combination of fluorescence microscopy and confocal microscopy. The adhesion forces between LHRH or EphA2 and human TNBC breast tissues are measured using force microscopy techniques that account for the potential effects of capillary forces due to the presence of water vapor. The corresponding adhesion energies are also determined using adhesion theory. The pull off forces and adhesion energies associated with higher grades of TNBC are shown to be greater than those associated with normal/non-tumorigenic human breast tissues, which were studied as controls. The observed increase in adhesion forces and adhesion energies are also correlated with the increasing incidence of LHRH/EphA2 receptors at higher grades of TNBC. The implications of the results are discussed for the development of targeted nanostructures for the detection and treatment of TNBC.

Direct Observation of Adhesion and Mechanical Behavior of a Single Poly(lactic-co-glycolic acid) (PLGA) Fiber Using an In Situ Technique for Tissue Engineering.

Nanometer- and submicrometer-sized fiber have been used as scaffolds for tissue engineering, because of their fundamental load-bearing properties in synergy with mechano-transduction. This study investigates a single biodegradable poly(lactic-co-glycolic acid) (PLGA) fiber's load-displacement behavior utilizing the nanoindentation technique coupled with a high-resolution in situ imaging system. It is demonstrated that a maximum force of ∼3 μN in the radial direction and displacement of at least 150% of fiber diameter should be applied to acquire the fiber's macroscopic mechanical properties for tissue engineering. The adhesion behavior of a single fiber is captured using a high-resolution camera. The digital image correlation (DIC) technique is adopted to quantify the adhesion force (∼25 μN) between the fiber and the tip. Adhesion force has also been quantified for the fiber after immersing in phosphate-buffered saline (PBS) to mimic the bioenvironment. A 4-fold increase in adhesion force after PBS treatment was observed due to water penetration and hydrolysis on the fiber's surface. A high similarity between mechanical properties of a single fiber and native tissues (elastic modulus of 10-25 kPa) and superior adhesion force (25-107.25 μN) was observed, which is excellent for promoting cell-matrix communication. Overall, this study examines the mechanics of a single fiber using innovative indentation and imaging processing techniques, disclosing its profound and striking roles in tissue engineering.