Soft lithography, a set of techniques for microfabrication, is based on printing and molding using elastomeric stamps with the patterns of interest in basrelief. As a technique for fabricating microstructures for biological applications, soft lithography overcomes many of the shortcomings of photolithography. In particular, soft lithography offers the ability to control the molecular structure of surfaces and to pattern the complex molecules relevant to biology, to fabricate channel structures appropriate for microfluidics, and to pattern and manipulate cells. For the relatively large feature sizes used in biology (> or = 50 microns), production of prototype patterns and structures is convenient, inexpensive, and rapid. Self-assembled monolayers of alkanethiolates on gold are particularly easy to pattern by soft lithography, and they provide exquisite control over surface biochemistry.
Multicellular spheroids are three dimensional in vitro microscale tissue analogs. The current article examines the suitability of spheroids as an in vitro platform for testing drug delivery systems. Spheroids model critical physiologic parameters present in vivo, including complex multicellular architecture, barriers to mass transport, and extracellular matrix deposition. Relative to two-dimensional cultures, spheroids also provide better target cells for drug testing and are appropriate in vitro model for studies of drug penetration. Key challenges associated with creation of uniformly sized spheroids, spheroids with small number of cells and co-culture spheroids are emphasized in the article. Moreover, the assay techniques required for the characterization of drug delivery and efficacy in spheroids and the challenges associated with such studies are discussed. Examples for the use of spheroids in drug delivery and testing are also emphasized. With these challenges and the possible solutions, multicellular spheroids are becoming an increasingly useful in vitro tool for drug screening and delivery to pathological tissues and organs.
This paper describes the use of surface plasmon resonance spectroscopy and self-assembled monolayers (SAMs) of alkanethiols on gold to evaluate the ability of surfaces terminating in different combinations of charged groups to resist the nonspecific adsorption of proteins from aqueous buffer. Mixed SAMs formed from a 1:1 combination of a thiol terminated in a trimethylammonium group and a thiol terminated in a sulfonate group adsorbed less than 1% of a monolayer of two proteins with different characteristics: fibrinogen and lysozyme. Single-component SAMs formed from thiols terminating in groups combining a positively charged moiety and a negatively charged moiety were also capable of resisting the adsorption of proteins. Single-component SAMs presenting single charges adsorbed nearly a full monolayer of protein.The amount of protein that adsorbed to mixed zwitterionic SAMs did not depend on the ionic strength or the pH of the buffer in which the protein was dissolved. The amount of protein that adsorbed to singlecomponent zwitterionic SAMs increased as the ionic strength of the buffer decreased; it also decreased as the pH of the buffer increased (at constant ionic strength). Single-component zwitterionic SAMs composed of thiols terminating in N,N-dimethyl-amino-propane-1-sulfonic acid (-N + (CH3)2CH2CH2CH2SO3 -) groups were substantially more effective at resisting adsorption of fibrinogen and lysozyme from buffer at physiological ionic strength and pH than single-component zwitterionic SAMs composed of thiols terminating in phosphoric acid 2-trimethylamino-ethyl ester (-OP(O)2 -OCH2CH2N + (CH3)3). Several of these zwitterionic SAMs were comparable to the best known systems for resisting nonspecific adsorption of protein.
Culture of cells as three-dimensional (3D) aggregates can enhance in vitro tests for basic biological research as well as for therapeutics development. Such 3D culture models, however, are often more complicated, cumbersome, and expensive than two-dimensional (2D) cultures. This paper describes a 384-well format hanging drop culture plate that makes spheroid formation, culture, and subsequent drug testing on the obtained 3D cellular constructs as straightforward to perform and adapt to existing high-throughput screening (HTS) instruments as conventional 2D cultures. Using this platform, we show that drugs with different modes of action produce distinct responses in the physiological 3D cell spheroids compared to conventional 2D cell monolayers. Specifically, the anticancer drug 5-fluorouracil (5-FU) has higher anti-proliferative effects on 2D cultures whereas the hypoxia activated drug commonly referred to as tirapazamine (TPZ) are more effective against 3D cultures. The multiplexed 3D hanging drop culture and testing plate provides an efficient way to obtain biological insights that are often lost in 2D platforms.
We describe a microfabricated airway system integrated with computerized air-liquid two-phase microfluidics that enables onchip engineering of human airway epithelia and precise reproduction of physiologic or pathologic liquid plug flows found in the respiratory system. Using this device, we demonstrate cellularlevel lung injury under flow conditions that cause symptoms characteristic of a wide range of pulmonary diseases. Specifically, propagation and rupture of liquid plugs that simulate surfactantdeficient reopening of closed airways lead to significant injury of small airway epithelial cells by generating deleterious fluid mechanical stresses. We also show that the explosive pressure waves produced by plug rupture enable detection of the mechanical cellular injury as crackling sounds.airway reopening ͉ small airway epithelial cells ͉ mechanical forces ͉ microfluidic cell culture
Developing metal-free organic phosphorescent materials is promising but challenging because achieving emissive triplet relaxation that outcompetes the vibrational loss of triplets, a key process to achieving phosphorescence, is difficult without heavy metal atoms. While recent studies reveal that bright room temperature phosphorescence can be realized in purely organic crystalline materials through directed halogen bonding, these organic phosphors still have limitations to practical applications due to the stringent requirement of high quality crystal formation. Here we report bright room temperature phosphorescence by embedding a purely organic phosphor into an amorphous glassy polymer matrix. Our study implies that the reduced beta (β)-relaxation of isotactic PMMA most efficiently suppresses vibrational triplet decay and allows the embedded organic phosphors to achieve a bright 7.5% phosphorescence quantum yield. We also demonstrate a microfluidic device integrated with a novel temperature sensor based on the metal-free purely organic phosphors in the temperature-sensitive polymer matrix. This unique system has many advantages: (i) simple device structures without feeding additional temperature sensing agents, (ii) bright phosphorescence emission, (iii) a reversible thermal response, and (iv) tunable temperature sensing ranges by using different polymers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.