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Plasmonic gold nanoparticles have been used increasingly in solid-state systems because of their applicability in fabricating novel sensors, heterogeneous catalysts, metamaterials, and thermoplasmonic substrates. While bottom-up colloidal syntheses take advantage of the chemical environment to control size, shape, composition, surface chemistry, and crystallography of the nanostructures precisely, it can be challenging to assemble nanoparticles rationally from suspension onto solid supports or within devices. In this Review, we discuss a powerful recent synthetic methodology, bottom-up in situ substrate growth, which circumvents time-consuming batch presynthesis, ligand exchange, and self-assembly steps by applying wet-chemical synthesis to form morphologically controlled nanostructures on supporting materials. First, we briefly introduce the properties of plasmonic nanostructures. Then we comprehensively summarize recent work that adds to the synthetic understanding of in situ geometrical and spatial control (patterning). Next, we briefly discuss applications of plasmonic hybrid materials prepared by in situ growth. Overall, despite the vast potential advantages of in situ growth, the mechanistic understanding of these methodologies remains far from established, providing opportunities and challenges for future research.
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Hydrogel droplets with inner compartments are valuable in various fields, including tissue engineering. A droplet-based biofabrication method is presented for the chaos-assisted production of architected spheres (CAPAS) for the rapid generation of multilayered hydrogel spheres (ranging from 0.6 to 3.5 mm in diameter) at high-throughput rates (up to 2000 spheres per min). This method is based on the use of chaotic advection generated by a Kenics static mixer (KSM) nozzle. The configuration of the KSM (i.e., the number of mixing elements) determines the number of compartments within the sphere. Sphere size is adjusted by flow rate, printhead outlet diameter, polymer concentration (sodium alginate or gelatin-methacryloyl (GelMA)), and crosslinking bath composition. This versatile system operates in dripping and jetting modes, preserving multilayered architecture in both modes. Proof-of-concept experiments with breast cancer (MDA-MB-231), human dermal fibroblast (HDF), and murine myoblast (C2C12) lines show over 80% cell viability immediately post-fabrication, maintained over extended culture (14 or 30 days). CAPAS is used to create a breast cancer model with cancer-tissue-like and healthy-tissue-like micro-niches to test paclitaxel doses. It is envisioned that CAPAS will enable high-throughput fabrication of hydrogel spheres for tissue engineering, chemical engineering, and material sciences applications.
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Hemostatic biomaterials show great promise in wound control for the treatment of uncontrolled bleeding associated with damaged tissues, traumatic wounds, and surgical incisions. A surge of interest has been directed at boosting hemostatic properties of bioactive materials via mechanisms triggering the coagulation cascade. A wide variety of biocompatible and biodegradable materials has been applied to the design of hemostatic platforms for rapid blood coagulation. Recent trends in the design of hemostatic agents emphasize chemical conjugation of charged moieties to biomacromolecules, physical incorporation of blood-coagulating agents in biomaterials systems, and superabsorbing materials in either dry (foams) or wet (hydrogel) states. In addition, tough bioadhesives are emerging for efficient and physical sealing of incisions. In this Review, we highlight the biomacromolecular design approaches adopted to develop hemostatic bioactive materials. We discuss the mechanistic pathways of hemostasis along with the current standard experimental procedures for characterization of the hemostasis efficacy. Finally, we discuss the potential for clinical translation of hemostatic technologies, future trends, and research opportunities for the development of next-generation surgical materials with hemostatic properties for wound management.
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Hemostáticos , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Materiais Biocompatíveis/uso terapêutico , Coagulação Sanguínea , Hemorragia/tratamento farmacológico , Hemostasia , Hemostáticos/química , Hemostáticos/farmacologia , Hemostáticos/uso terapêutico , HumanosRESUMO
Advances in gene editing are leading to new medical interventions where patients' own cells are used for stem cell therapies and immunotherapies. One of the key limitations to translating these treatments to the clinic is the need for scalable technologies for engineering cells efficiently and safely. Toward this goal, microfluidic strategies to induce membrane pores and permeability have emerged as promising techniques to deliver biomolecular cargo into cells. As these technologies continue to mature, there is a need to achieve efficient, safe, nontoxic, fast, and economical processing of clinically relevant cell types. We demonstrate an acoustofluidic sonoporation method to deliver plasmids to immortalized and primary human cell types, based on pore formation and permeabilization of cell membranes with acoustic waves. This acoustofluidic-mediated approach achieves fast and efficient intracellular delivery of an enhanced green fluorescent protein-expressing plasmid to cells at a scalable throughput of 200,000 cells/min in a single channel. Analyses of intracellular delivery and nuclear membrane rupture revealed mechanisms underlying acoustofluidic delivery and successful gene expression. Our studies show that acoustofluidic technologies are promising platforms for gene delivery and a useful tool for investigating membrane repair.
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Técnicas de Transferência de Genes , Terapia Genética/métodos , Transplante de Células-Tronco Hematopoéticas/métodos , Sistema Hematopoético , Células-Tronco , Sobrevivência Celular , Citoplasma , Expressão Gênica , Técnicas de Transferência de Genes/instrumentação , Terapia Genética/instrumentação , Proteínas de Fluorescência Verde/genética , Humanos , Células Jurkat , Plasmídeos , SomRESUMO
Emerging sutureless wound-closure techniques have led to paradigm shifts in wound management. State-of-the-art biomaterials offer biocompatible and biodegradable platforms enabling high cohesion (toughness) and adhesion for rapid bleeding control as well as robust attachment of implantable devices. Tough bioadhesion stems from the synergistic contributions of cohesive and adhesive interactions. This Review provides a biomacromolecular design roadmap for the development of tough adhesive surgical sealants. We discuss a library of materials and methods to introduce toughness and adhesion to biomaterials. Intrinsically tough and elastic polymers are leveraged primarily by introducing strong but dynamic inter- and intramolecular interactions either through polymer chain design or using crosslink regulating additives. In addition, many efforts have been made to promote underwater adhesion via covalent/noncovalent bonds, or through micro/macro-interlock mechanisms at the tissue interfaces. The materials settings and functional additives for this purpose and the related characterization methods are reviewed. Measurements and reporting needs for fair comparisons of different materials and their properties are discussed. Finally, future directions and further research opportunities for developing tough bioadhesive surgical sealants are highlighted.
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Adesivos Teciduais , Adesivos Teciduais/química , Materiais Biocompatíveis/química , Hidrogéis/química , Adesivos , PolímerosRESUMO
Deficiencies in either lamin B1 or lamin B2 cause both defective migration of cortical neurons in the developing brain and reduced neuronal survival. The neuronal migration abnormality is explained by a weakened nuclear lamina that interferes with nucleokinesis, a nuclear translocation process required for neuronal migration. In contrast, the explanation for impaired neuronal survival is poorly understood. We hypothesized that the forces imparted on the nucleus during neuronal migration result in nuclear membrane (NM) ruptures, causing interspersion of nuclear and cytoplasmic contents-and ultimately cell death. To test this hypothesis, we bred Lmnb1-deficient mice that express a nuclear-localized fluorescent Cre reporter. Migrating neurons within the cortical plate of E18.5 Lmnb1-deficient embryos exhibited NM ruptures, evident by the escape of the nuclear-localized reporter into the cytoplasm and NM discontinuities by electron microscopy. The NM ruptures were accompanied by DNA damage and cell death. The NM ruptures were not observed in nonmigrating cells within the ventricular zone. NM ruptures, DNA damage, and cell death were also observed in cultured Lmnb1-/- and Lmnb2-/- neurons as they migrated away from neurospheres. To test whether mechanical forces on the cell nucleus are relevant to NM ruptures in migrating neurons, we examined cultured Lmnb1-/- neurons when exposed to external constrictive forces (migration into a field of tightly spaced silicon pillars). As the cells entered the field of pillars, there were frequent NM ruptures, accompanied by DNA damage and cell death.
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Morte Celular/fisiologia , Movimento Celular/fisiologia , Lamina Tipo B/metabolismo , Neurônios/metabolismo , Membrana Nuclear/metabolismo , Lâmina Nuclear/metabolismo , Animais , Linhagem Celular , Sobrevivência Celular , Citoplasma/metabolismo , Dano ao DNA , Regulação da Expressão Gênica , Lamina Tipo B/genética , Camundongos , Camundongos Knockout , Neurônios/citologia , Lâmina Nuclear/genéticaRESUMO
The clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) is an efficient and precise gene-editing technology that offers a versatile solution for establishing treatments directed at genetic diseases. Currently, CRISPR/Cas9 delivery into cells relies primarily on viral vectors, which suffer from limitations in packaging capacity and safety concerns. These issues with a nonviral delivery strategy are addressed, where Cas9â¢sgRNA ribonucleoprotein (RNP) complexes can be encapsulated into supramolecular nanoparticles (SMNP) to form RNPâSMNPs, which can then be delivered into targeted cells via supramolecular nanosubstrate-mediated delivery. Utilizing the U87 glioblastoma cell line as a model system, a variety of parameters for cellular-uptake of the RNP-laden nanoparticles are examined. Dose- and time-dependent CRISPR/Cas9-mediated gene disruption is further examined in a green fluorescent protein (GFP)-expressing U87 cell line (GFP-U87). The utility of an optimized SMNP formulation in co-delivering Cas9 protein and two sgRNAs that target deletion of exons 45-55 (708 kb) of the dystrophin gene is demonstrated. Mutations in this region lead to Duchenne muscular dystrophy, a severe genetic muscle wasting disease. Efficient delivery of these gene deletion cargoes is observed in a human cardiomyocyte cell line (AC16), induced pluripotent stem cells, and mesenchymal stem cells.
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Sistemas CRISPR-Cas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Proteína 9 Associada à CRISPR , Edição de Genes , Vetores Genéticos , HumanosRESUMO
A multi-disciplinary work group involving stakeholders from various backgrounds and societies was convened to develop guidelines for the management of reconstruction after skin cancer resection. The goal was to identify areas of common ground and provide evidence-based recommendations to improve patient care. Given the heterogeneity of reconstructive techniques and clinical scenarios, investigation centered around common elements in the process. In some cases, a distinction was made between treatment options in the office-based setting as opposed to those in the facility setting. A systematic literature review was performed, and an established appraisal process was used to rate the quality of relevant scientific research (Grading of Recommendations Assessment, Development, and Evaluation methodology). Final recommendations are related to concepts concerning the timing of reconstruction, management of anticoagulation, use of antibiotics, methods of pain control, and follow-up assessment. At times, there was insufficient evidence to make high-level recommendations. The literature analysis highlights the need for additional methodologically robust studies in this area, to help guide clinical practice.
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Procedimentos Cirúrgicos Dermatológicos/normas , Neoplasias Cutâneas/cirurgia , Medicina Baseada em Evidências , Humanos , Guias de Prática Clínica como AssuntoRESUMO
SUMMARY: A multi-disciplinary work group involving stakeholders from various backgrounds and societies was convened to develop guidelines for the management of reconstruction after skin cancer resection. The goal was to identify areas of common ground and provide evidence-based recommendations to improve patient care. Given the heterogeneity of reconstructive techniques and clinical scenarios, investigation centered around common elements in the process. In some cases, a distinction was made between treatment options in the office-based setting as opposed to those in the facility setting. A systematic literature review was performed, and an established appraisal process was used to rate the quality of relevant scientific research (Grading of Recommendations Assessment, Development, and Evaluation methodology). Final recommendations are related to concepts concerning the timing of reconstruction, management of anticoagulation, use of antibiotics, methods of pain control, and follow-up assessment. At times, there was insufficient evidence to make high-level recommendations. The literature analysis highlights the need for additional methodologically robust studies in this area, to help guide clinical practice.
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Procedimentos Cirúrgicos Dermatológicos/normas , Medicina Baseada em Evidências , Neoplasias Cutâneas/cirurgia , Humanos , Guias de Prática Clínica como AssuntoRESUMO
We detect short oligonucleotides and distinguish between sequences that differ by a single base, using label-free, electronic field-effect transistors (FETs). Our sensing platform utilizes ultrathin-film indium oxide FETs chemically functionalized with single-stranded DNA (ssDNA). The ssDNA-functionalized semiconducting channels in FETs detect fully complementary DNA sequences and differentiate these sequences from those having different types and locations of single base-pair mismatches. Changes in charge associated with surface-bound ssDNA vs double-stranded DNA (dsDNA) alter FET channel conductance to enable detection due to differences in DNA duplex stability. We illustrate the capability of ssDNA-FETs to detect complementary RNA sequences and to distinguish from RNA sequences with single nucleotide variations. The development and implementation of electronic biosensors that rapidly and sensitively detect and differentiate oligonucleotides present new opportunities in the fields of disease diagnostics and precision medicine.
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Técnicas Biossensoriais , Transistores Eletrônicos , Pareamento Incorreto de Bases , DNA/genética , DNA de Cadeia Simples/genética , Nucleotídeos , RNARESUMO
Spin-dependent and enantioselective electron-molecule scattering occurs in photoelectron transmission through chiral molecular films. This spin selectivity leads to electron spin filtering by molecular helices, with increasing magnitude concomitant with increasing numbers of helical turns. Using ultraviolet photoelectron spectroscopy, we measured spin-selective surface charging accompanying photoemission from ferromagnetic substrates functionalized with monolayers of mercurated DNA hairpins that constitute only one helical turn. Mercury ions bind specifically at thymine-thymine mismatches within self-hybridized single-stranded DNA, enabling precise control over the number and position of Hg2+ along the helical axis. Differential charging of the organic layers, manifested as substrate-magnetization-dependent photoionization energies, was observed for DNA hairpins containing Hg2+; no differences were measured for hairpin monolayers in the absence of Hg2+. Inversion of the DNA helical secondary structure at increased metal loading led to complementary inversion in spin selectivity. We attribute these results to increased scattering probabilities from relativistic enhancement of spin-orbit interactions in mercurated DNA.
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DNA de Cadeia Simples/química , DNA/química , Imãs/química , Mercúrio/química , Fenômenos Biofísicos , DNA/ultraestrutura , DNA de Cadeia Simples/ultraestrutura , Transporte de Elétrons/genética , Elétrons , Humanos , Espectroscopia Fotoeletrônica , EstereoisomerismoRESUMO
Plasmonic nanostructures have a wide range of applications, including chemical and biological sensing. However, the development of techniques to fabricate submicrometer-sized plasmonic structures over large scales remains challenging. We demonstrate a high-throughput, cost-effective approach to fabricate Au nanoribbons via chemical lift-off lithography (CLL). Commercial HD-DVDs were used as large-area templates for CLL. Transparent glass slides were coated with Au/Ti films and functionalized with self-assembled alkanethiolate monolayers. Monolayers were patterned with lines via CLL. The lifted-off, exposed regions of underlying Au were selectively etched into large-area grating-like patterns (200 nm line width; 400 nm pitch; 60 nm height). After removal of the remaining monolayers, a thin In2O3 layer was deposited and the resulting gratings were used as plasmonic sensors. Distinct features in the extinction spectra varied in their responses to refractive index changes in the solution environment with a maximum bulk sensitivity of â¼510 nm/refractive index unit. Sensitivity to local refractive index changes in the near-field was also achieved, as evidenced by real-time tracking of lipid vesicle or protein adsorption. These findings show how CLL provides a simple and economical means to pattern large-area plasmonic nanostructures for applications in optoelectronics and sensing.
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Ouro/química , Índio/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Ressonância de Plasmônio de SuperfícieRESUMO
Gold nanoparticles are exciting materials in nanotechnology and nanoscience research and are being applied across a wide range of fields including imaging, chemical sensing, energy storage, and cancer therapies. In this experiment, students will synthesize two sizes of gold nanospheres (~20 nm and ~100 nm) and will create gold nanostars utilizing a seed-mediated growth synthetic approach. Students will compare how each sample interacts differently with light (absorption and scattering) based on the nanoparticles' size and shape. This experiment is ideal for high-school and early undergraduate students since all reagents are non-toxic, affordable, and no special characterization equipment is required.
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Tumor-derived extracellular vesicles (EVs) play essential roles in intercellular communication during tumor growth and metastatic evolution. Currently, little is known about the possible roles of tumor-derived EVs in sarcoma because the lack of specific surface markers makes it technically challenging to purify sarcoma-derived EVs. In this study, a specific purification system is developed for Ewing sarcoma (ES)-derived EVs by coupling covalent chemistry-mediated EV capture/ release within a nanostructure-embedded microchip. The purification platform-ES-EV Click Chip-takes advantage of specific anti-LINGO-1 recognition and sensitive click chemistry-mediated EV capture, followed by disulfide cleavage-driven EV release. Since the device is capable of specific and efficient purification of intact ES EVs with high purity, ES-EV Click Chip is ideal for conducting downstream functional studies of ES EVs. Absolute quantification of the molecular hallmark of ES (i.e., EWS rearrangements) using reverse transcription Droplet Digital PCR enables specific quantification of ES EVs. The purified ES EVs can be internalized by recipient cells and transfer their mRNA cargoes, exhibiting their biological intactness and potential role as biological shuttles in intercellular communication.
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Drawbacks of traditional approximate (Wald test-based) and exact (Clopper-Pearson) confidence intervals for a binomial proportion are well-recognized. Alternatives include an interval based on inverting the score test, adaptations of exact testing, and Bayesian credible intervals derived from uniform or Jeffreys beta priors. We recommend a new interval intermediate between the Clopper-Pearson and Jeffreys in terms of both width and coverage. Our strategy selects a value κ between 0 and 0.5 based on stipulated coverage criteria over a grid of regions comprising the parameter space, and bases lower and upper limits of a credible interval on Beta(κ, 1- κ) and Beta(1- κ, κ) priors, respectively. The result tends toward the Jeffreys interval if the criterion is to ensure an average overall coverage rate (1-α) across a single region of width 1, and toward the Clopper-Pearson if the goal is to constrain both lower and upper lack of coverage rates at α/2 with region widths approaching zero. We suggest an intermediate target that ensures all average lower and upper lack of coverage rates over a specified set of regions are ≤ α/2. Interval width subject to these criteria is readily optimized computationally, and we demonstrate particular benefits in terms of coverage balance.
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Spin selectivity in photo-emission from ferromagnetic substrates functionalized with chiral organic films was analyzed by ultraviolet photoelectron spectroscopy at room temperature. Using radiation with photon energy greater than the ionization potential of the adsorbed molecules, photoelectrons were collected that originated from both underlying ferromagnetic substrates and the organic films, with kinetic energies in the range of ca. 0-18 eV. We investigated chiral organic films composed of self-assembled monolayers of α-helical peptides and electrostatically adsorbed films of the protein, bovine serum albumin, with different α-helix and ß-sheet contents. Ultraviolet photoelectron spectral widths were found to depend on substrate magnetization orientation and polarization, which we attribute to helicity-dependent molecular ionization cross sections arising from photoelectron impact, possibly resulting in spin-polarized holes. These interactions between spin-polarized photoelectrons and chiral molecules are physically manifested as differences in the measured photoionization energies of the chiral molecular films. Substrate magnetization-dependent ionization energies and work function values were deconvoluted using surface charge neutralization techniques, permitting the measurement of relative spin-dependent energy barriers to transmission through chiral organic films.
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Nanopartículas de Magnetita/química , Peptídeos/química , Adsorção , Cinética , Tamanho da Partícula , Espectrofotometria UltravioletaRESUMO
Nanoribbon- and nanowire-based field-effect transistors (FETs) have attracted significant attention due to their high surface-to-volume ratios, which make them effective as chemical and biological sensors. However, the conventional nanofabrication of these devices is challenging and costly, posing a major barrier to widespread use. We report a high-throughput approach for producing arrays of ultrathin (â¼3 nm) In2O3 nanoribbon FETs at the wafer scale. Uniform films of semiconducting In2O3 were prepared on Si/SiO2 surfaces via a sol-gel process prior to depositing Au/Ti metal layers. Commercially available high-definition digital versatile discs were employed as low-cost, large-area templates to prepare polymeric stamps for chemical lift-off lithography, which selectively removed molecules from self-assembled monolayers functionalizing the outermost Au surfaces. Nanoscale chemical patterns, consisting of one-dimensional lines (200 nm wide and 400 nm pitch) extending over centimeter length scales, were etched into the metal layers using the remaining monolayer regions as resists. Subsequent etch processes transferred the patterns into the underlying In2O3 films before the removal of the protective organic and metal coatings, revealing large-area nanoribbon arrays. We employed nanoribbons in semiconducting FET channels, achieving current on-to-off ratios over 107 and carrier mobilities up to 13.7 cm2 V-1 s-1. Nanofabricated structures, such as In2O3 nanoribbons and others, will be useful in nanoelectronics and biosensors. The technique demonstrated here will enable these applications and expand low-cost, large-area patterning strategies to enable a variety of materials and design geometries in nanoelectronics.
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Índio/química , Nanotecnologia/métodos , Nanotubos de Carbono/química , Semicondutores , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Ouro/química , Nanotecnologia/economia , Nanotecnologia/instrumentação , Nanotubos de Carbono/ultraestrutura , Dióxido de Silício/química , Titânio/químicaRESUMO
BACKGROUND: Little is known about the body weight goals and trends of stroke survivors, despite evidence that overweight and obesity can negatively influence poststroke rehabilitation outcomes. Thus, the purpose of this study was to identify self-reported body weight trends over time in stroke survivors and nonstroke controls (>50 years old) and describe the methods used to attempt to achieve body weight goals. METHODS: Self-reported body weight 1) at age 25 years, 2) 10 years prior to the current assessment, 3) 1 year prior to the current assessment, 4) current weight, and 5) age of heaviest body weight were collected from adults self-reporting a stroke in the 2011-2012 and 2013-2014 National Health and Nutrition Examination Surveys (stroke: Nâ¯=â¯387 and nonstroke: Nâ¯=â¯5085). Questionnaires were used to assess body weight goals and weight loss techniques during the previous year. RESULTS: Of the stroke survivors, 54% reported that their heaviest weight occurred after their stroke. Approximately 70% of stroke and nonstroke were overweight or obese. Only 24% of stroke survivors reported trying to lose weight compared with 35% of nonstroke, with only 10%-15% successful (≥5% body weight loss), during the past year. Popular weight loss methods in both groups included eating less, exercising, and eating more fruits/vegetables. The majority of stroke survivors report their heaviest weight after their stroke and a desire to weigh less; however, few report successful weight loss. CONCLUSIONS: Future research is needed to identify optimal body weight and ways to incorporate preferred methods of lifestyle modification, including diet and exercise, to promote weight management in stroke survivors.
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Comportamentos Relacionados com a Saúde , Conhecimentos, Atitudes e Prática em Saúde , Obesidade/terapia , Autorrelato , Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral/terapia , Redução de Peso , Adulto , Idoso , Restrição Calórica , Dieta Saudável , Exercício Físico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Obesidade/epidemiologia , Obesidade/fisiopatologia , Obesidade/psicologia , Fatores de Proteção , Estudos Retrospectivos , Fatores de Risco , Comportamento de Redução do Risco , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/fisiopatologia , Acidente Vascular Cerebral/psicologia , Fatores de Tempo , Resultado do Tratamento , Estados Unidos/epidemiologiaRESUMO
BACKGROUND: Chest wall recontouring is a common surgical treatment of gender dysphoria in transmen and nonbinary individuals assigned female at birth. This study reviews more than 20 years of cases to identify risk factors for postoperative complications and likelihood of preservation of nipple sensation. METHODS: One hundred thirty-seven cases of female-to-male chest wall recontouring by a single surgeon from 1994 to 2016 were reviewed, 99 of which were included for final analysis. Double-incision free nipple graft and double incision with nipple transposition on a pedicle were the most common techniques used. Complication rates between these 2 techniques were compared, and multivariate analysis was used to identify possible predictors of major complications, and minor complications. RESULTS: No significant risk factors for major complications were identified. With regard to minor complications, advanced patient age (odds ratio [OR], 1.67; P = 0.03) and early surgical experience (OR, 5.08; P = 0.001) were found to be associated with increased risk. Preoperative hormonal treatment was found to trend toward a protective effect (OR, 0.13; P = 0.07). CONCLUSIONS: Any of the reviewed techniques are safe in practice; however, there is a learning curve associated with their use, and longer follow-up will allow for the identification of late complications. The double incision with nipple transposition on a pedicle technique can be considered for patients for whom depigmentation of the nipple-areola complex is a significant concern, especially if they are willing to tolerate a potentially suboptimal chest contour.
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Disforia de Gênero/cirurgia , Mamoplastia/métodos , Cirurgia de Readequação Sexual/métodos , Parede Torácica/cirurgia , Adolescente , Adulto , Feminino , Seguimentos , Humanos , Curva de Aprendizado , Masculino , Mastectomia , Pessoa de Meia-Idade , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Estudos Retrospectivos , Fatores de Risco , Pessoas Transgênero , Resultado do Tratamento , Adulto JovemRESUMO
We report a facile, high-throughput soft lithography process that utilizes nanoscale channels formed naturally at the edges of microscale relief features on soft, elastomeric stamps. Upon contact with self-assembled monolayer (SAM) functionalized substrates, the roof of the stamp collapses, resulting in the selective removal of SAM molecules via a chemical lift-off process. With this technique, which we call self-collapse lithography (SCL), sub-30 nm patterns were achieved readily using masters with microscale features prepared by conventional photolithography. The feature sizes of the chemical patterns can be varied continuously from â¼2 µm to below 30 nm by decreasing stamp relief heights from 1 µm to 50 nm. Likewise, for fixed relief heights, reducing the stamp Young's modulus from â¼2.0 to â¼0.8 MPa resulted in shrinking the features of resulting patterns from â¼400 to â¼100 nm. The self-collapse mechanism was studied using finite element simulation methods to model the competition between adhesion and restoring stresses during patterning. These results correlate well with the experimental data and reveal the relationship between the line widths, channel heights, and Young's moduli of the stamps. In addition, SCL was applied to pattern two-dimensional arrays of circles and squares. These chemical patterns served as resists during etching processes to transfer patterns to the underlying materials (e.g., gold nanostructures). This work provides new insights into the natural propensity of elastomeric stamps to self-collapse and demonstrates a means of exploiting this behavior to achieve patterning via nanoscale chemical lift-off lithography.