We are a discovery-driven research group working at the interface between developmental biology, bioengineering, and statistical physics. We combine quantitative organism-wide fluorescence imaging ("deep imaging"), functional genomics ("deep sequencing"), and physical modeling to understand the fundamental rules that control collective cell behaviors to optimize tissue regeneration, adaptation, and evolution. We also seek for opportunities for applying these rules to improve multicellular engineering systems.

Academic Appointments

Honors & Awards

  • Young Investigator Award, Human Frontier Science Program (2019)
  • Beckman Young Investigator Award, Arnold and Mabel Beckman Foundation (2017)
  • Hellman Faculty Scholar Award, Hellman Fellows Fund (2017)
  • Baxter Faculty Scholar Award, Donald E. and Delia B. Baxter Foundation (2016)
  • Career Award at the Scientific Interface, Burroughs Wellcome Fund (2013)
  • Victor K. LaMer Award, American Chemical Society (2012)
  • Frank J. Padden, Jr. Award, American Physical Society (2010)

Professional Education

  • Ph.D., University of Illinois, Urbana-Champaign, Materials Science (2011)
  • M.S., B.S., Zhejiang University, Materials Science (2006)

Stanford Advisees

All Publications

  • Chromatic neuronal jamming in a primitive brain. NATURE PHYSICS Khariton, M., Kong, X., Qin, J., Wang, B. 2020; 16 (5): 553-557
  • Mechanically resolved imaging of bacteria using expansion microscopy. PLoS biology Lim, Y., Shiver, A. L., Khariton, M., Lane, K. M., Ng, K. M., Bray, S. R., Qin, J., Huang, K. C., Wang, B. 2019; 17 (10): e3000268


    Imaging dense and diverse microbial communities has broad applications in basic microbiology and medicine, but remains a grand challenge due to the fact that many species adopt similar morphologies. While prior studies have relied on techniques involving spectral labeling, we have developed an expansion microscopy method (muExM) in which bacterial cells are physically expanded prior to imaging. We find that expansion patterns depend on the structural and mechanical properties of the cell wall, which vary across species and conditions. We use this phenomenon as a quantitative and sensitive phenotypic imaging contrast orthogonal to spectral separation to resolve bacterial cells of different species or in distinct physiological states. Focusing on host-microbe interactions that are difficult to quantify through fluorescence alone, we demonstrate the ability of muExM to distinguish species through an in vitro defined community of human gut commensals and in vivo imaging of a model gut microbiota, and to sensitively detect cell-envelope damage caused by antibiotics or previously unrecognized cell-to-cell phenotypic heterogeneity among pathogenic bacteria as they infect macrophages.

    View details for DOI 10.1371/journal.pbio.3000268

    View details for PubMedID 31622337

  • Self-assembling manifolds in single-cell RNA sequencing data. ELIFE Tarashansky, A. J., Xue, Y., Li, P., Quake, S. R., Wang, B. 2019; 8: e48994

    View details for DOI 10.7554/eLife.48994

  • Stem cell heterogeneity drives the parasitic life cycle of Schistosoma mansoni ELIFE Wang, B., Lee, J., Li, P., Section, A., Yang, H., Liu, C., Zhao, M., Newmark, P. A. 2018; 7
  • Memoryless self-reinforcing directionality in endosomal active transport within living cells NATURE MATERIALS Chen, K., Wang, B., Granick, S. 2015; 14 (6): 589-593


    In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.

    View details for DOI 10.1038/NMAT4239

    View details for Web of Science ID 000354801500021

    View details for PubMedID 25822692

  • Functional genomic characterization of neoblast-like stem cells in larval Schistosoma mansoni ELIFE Wang, B., Collins, J. J., Newmark, P. A. 2013; 2


    Schistosomes infect hundreds of millions of people in the developing world. Transmission of these parasites relies on a stem cell-driven, clonal expansion of larvae inside a molluscan intermediate host. How this novel asexual reproductive strategy relates to current models of stem cell maintenance and germline specification is unclear. Here, we demonstrate that this proliferative larval cell population (germinal cells) shares some molecular signatures with stem cells from diverse organisms, in particular neoblasts of planarians (free-living relatives of schistosomes). We identify two distinct germinal cell lineages that differ in their proliferation kinetics and expression of a nanos ortholog. We show that a vasa/PL10 homolog is required for proliferation and maintenance of both populations, whereas argonaute2 and a fibroblast growth factor receptor-encoding gene are required only for nanos-negative cells. Our results suggest that an ancient stem cell-based developmental program may have enabled the evolution of the complex life cycle of parasitic flatworms. DOI:

    View details for DOI 10.7554/eLife.00768

    View details for Web of Science ID 000328622300001

    View details for PubMedID 23908765

  • Adult somatic stem cells in the human parasite Schistosoma mansoni NATURE Collins, J. J., Wang, B., Lambrus, B. G., Tharp, M. E., Iyer, H., Newmark, P. A. 2013; 494 (7438): 476-479


    Schistosomiasis is among the most prevalent human parasitic diseases, affecting more than 200 million people worldwide. The aetiological agents of this disease are trematode flatworms (Schistosoma) that live and lay eggs within the vasculature of the host. These eggs lodge in host tissues, causing inflammatory responses that are the primary cause of morbidity. Because these parasites can live and reproduce within human hosts for decades, elucidating the mechanisms that promote their longevity is of fundamental importance. Although adult pluripotent stem cells, called neoblasts, drive long-term homeostatic tissue maintenance in long-lived free-living flatworms (for example, planarians), and neoblast-like cells have been described in some parasitic tapeworms, little is known about whether similar cell types exist in any trematode species. Here we describe a population of neoblast-like cells in the trematode Schistosoma mansoni. These cells resemble planarian neoblasts morphologically and share their ability to proliferate and differentiate into derivatives of multiple germ layers. Capitalizing on available genomic resources and RNA-seq-based gene expression profiling, we find that these schistosome neoblast-like cells express a fibroblast growth factor receptor orthologue. Using RNA interference we demonstrate that this gene is required for the maintenance of these neoblast-like cells. Our observations indicate that adaptation of developmental strategies shared by free-living ancestors to modern-day schistosomes probably contributed to the success of these animals as long-lived obligate parasites. We expect that future studies deciphering the function of these neoblast-like cells will have important implications for understanding the biology of these devastating parasites.

    View details for DOI 10.1038/nature11924

    View details for Web of Science ID 000315661500038

    View details for PubMedID 23426263

    View details for PubMedCentralID PMC3586782

  • When Brownian diffusion is not Gaussian NATURE MATERIALS Wang, B., Kuo, J., Bae, S. C., Granick, S. 2012; 11 (6): 481-485

    View details for DOI 10.1038/nmat3308

    View details for Web of Science ID 000304320300003

    View details for PubMedID 22614505

  • Anomalous yet Brownian PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, B., Anthony, S. M., Bae, S. C., Granick, S. 2009; 106 (36): 15160-15164


    We describe experiments using single-particle tracking in which mean-square displacement is simply proportional to time (Fickian), yet the distribution of displacement probability is not Gaussian as should be expected of a classical random walk but, instead, is decidedly exponential for large displacements, the decay length of the exponential being proportional to the square root of time. The first example is when colloidal beads diffuse along linear phospholipid bilayer tubes whose radius is the same as that of the beads. The second is when beads diffuse through entangled F-actin networks, bead radius being less than one-fifth of the actin network mesh size. We explore the relevance to dynamic heterogeneity in trajectory space, which has been extensively discussed regarding glassy systems. Data for the second system might suggest activated diffusion between pores in the entangled F-actin networks, in the same spirit as activated diffusion and exponential tails observed in glassy systems. But the first system shows exceptionally rapid diffusion, nearly as rapid as for identical colloids in free suspension, yet still displaying an exponential probability distribution as in the second system. Thus, although the exponential tail is reminiscent of glassy systems, in fact, these dynamics are exceptionally rapid. We also compare with particle trajectories that are at first subdiffusive but Fickian at the longest measurement times, finding that displacement probability distributions fall onto the same master curve in both regimes. The need is emphasized for experiments, theory, and computer simulation to allow definitive interpretation of this simple and clean exponential probability distribution.

    View details for DOI 10.1073/pnas.0903554106

    View details for Web of Science ID 000269632400015

    View details for PubMedID 19666495

  • Nanoparticle-induced surface reconstruction of phospholipid membranes PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, B., Zhang, L., Bae, S. C., Granick, S. 2008; 105 (47): 18171-18175


    The nonspecific adsorption of charged nanoparticles onto single-component phospholipid bilayers bearing phosphocholine headgroups is shown, from fluorescence and calorimetry experiments, to cause surface reconstruction at the points where nanoparticles adsorb. Nanoparticles of negative charge induce local gelation in otherwise fluid bilayers; nanoparticles of positive charge induce otherwise gelled membranes to fluidize locally. Through this mechanism, the phase state deviates from the nominal phase transition temperature by tens of degrees. This work generalizes the notions of environmentally induced surface reconstruction, prominent in metals and semiconductors. Bearing in mind that chemical composition in these single-component lipid bilayers is the same everywhere, this offers a mechanism to generate patchy functional properties in phospholipid membranes.

    View details for DOI 10.1073/pnas.0807296105

    View details for Web of Science ID 000261489300026

    View details for PubMedID 19011086

  • Identification of anisomycin, prodigiosin and obatoclax as compounds with broad-spectrum anti-parasitic activity. PLoS neglected tropical diseases Ehrenkaufer, G., Li, P., Stebbins, E. E., Kangussu-Marcolino, M. M., Debnath, A., White, C. V., Moser, M. S., DeRisi, J., Gisselberg, J., Yeh, E., Wang, S. C., Company, A. H., Monti, L., Caffrey, C. R., Huston, C. D., Wang, B., Singh, U. 2020; 14 (3): e0008150


    Parasitic infections are a major source of human suffering, mortality, and economic loss, but drug development for these diseases has been stymied by the significant expense involved in bringing a drug though clinical trials and to market. Identification of single compounds active against multiple parasitic pathogens could improve the economic incentives for drug development as well as simplifying treatment regimens. We recently performed a screen of repurposed compounds against the protozoan parasite Entamoeba histolytica, causative agent of amebic dysentery, and identified four compounds (anisomycin, prodigiosin, obatoclax and nithiamide) with low micromolar potency and drug-like properties. Here, we extend our investigation of these drugs. We assayed the speed of killing of E. histolytica trophozoites and found that all four have more rapid action than the current drug of choice, metronidazole. We further established a multi-institute collaboration to determine whether these compounds may have efficacy against other parasites and opportunistic pathogens. We found that anisomycin, prodigiosin and obatoclax all have broad-spectrum antiparasitic activity in vitro, including activity against schistosomes, T. brucei, and apicomplexan parasites. In several cases, the drugs were found to have significant improvements over existing drugs. For instance, both obatoclax and prodigiosin were more efficacious at inhibiting the juvenile form of Schistosoma than the current standard of care, praziquantel. Additionally, low micromolar potencies were observed against pathogenic free-living amebae (Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba castellanii), which cause CNS infection and for which there are currently no reliable treatments. These results, combined with the previous human use of three of these drugs (obatoclax, anisomycin and nithiamide), support the idea that these compounds could serve as the basis for the development of broad-spectrum anti-parasitic drugs.

    View details for DOI 10.1371/journal.pntd.0008150

    View details for PubMedID 32196500

  • Phase transitions in mutualistic communities under invasion PHYSICAL BIOLOGY Bray, S. R., Fan, Y., Wang, B. 2019; 16 (4)
  • Deep line-temporal focusing with high axial resolution and a large field-of-view using intracavity control and incoherent pulse shaping OPTICS LETTERS Lou, K., Wang, B., Jee, A., Granick, S., Amblard, F. 2018; 43 (20): 4919–22


    Line-temporal focusing has been recognized as an elegant strategy that provides two-photon microscopy with an effective means for fast imaging through parallelization, together with an improved resilience to scattering for deep imaging. However, the axial resolution remains sub-optimal, except when using high NA objectives and a small field-of-view. With the introduction of an intracavity control of the spectral width of the femtosecond laser to adaptively fill the back aperture of the objective lens, line-temporal focusing two-photon microscopy is demonstrated to reach near-diffraction-limited axial resolution with a large back-aperture objective lens, and improved immunity to sample scattering. In addition, a new incoherent flattop beam shaping method is proposed which provides a uniform contrast with little degradation of the axial resolution along the focus line, even deep in the sample. This is demonstrated in large volumetric imaging of mouse lung samples.

    View details for DOI 10.1364/OL.43.004919

    View details for Web of Science ID 000447265700017

    View details for PubMedID 30320783

  • Nanomedicine Approaches Against Parasitic Worm Infections. Advanced healthcare materials Li, P., Rios Coronado, P. E., Longstaff, X. R., Tarashansky, A. J., Wang, B. 2018: e1701494


    Nanomedicine approaches have the potential to transform the battle against parasitic worm (helminth) infections, a major global health scourge from which billions are currently suffering. It is anticipated that the intersection of two currently disparate fields, nanomedicine and helminth biology, will constitute a new frontier in science and technology. This progress report surveys current innovations in these research fields and discusses research opportunities. In particular, the focus is on: (1) major challenges that helminth infections impose on mankind; (2) key aspects of helminth biology that inform future research directions; (3) efforts to construct nanodelivery platforms to target drugs and genes to helminths hidden in their hosts; (4) attempts in applying nanotechnology to enable vaccination against helminth infections; (5) outlooks in utilizing nanoparticles to enhance immunomodulatory activities of worm-derived factors to cure allergy and autoimmune diseases. In each section, achievements are summarized, limitations are explored, and future directions are assessed.

    View details for PubMedID 29602254

  • Biomimetic Virulomics for Capture and Identification of Cell-Type Specific Effector Proteins. ACS nano Lapek, J. D., Fang, R. H., Wei, X., Li, P., Wang, B., Zhang, L., Gonzalez, D. J. 2017; 11 (12): 11831–38


    An unmet challenge in the study of disease is to accurately streamline the identification of important virulence factors. Traditional, genetically driven approaches miss biologically relevant markers due to discordance between the genome and proteome. Here, we developed a nanotechnology-enabled affinity enrichment strategy coupled with multiplexed quantitative proteomics, namely Biomimetic Virulomics, for successful identification of cell-type specific effector proteins of both prokaryotic and eukaryotic pathogens. We highlight the power of Biomimetic Virulomics by capturing known virulence factors in a high-throughput, cell-type guided fashion. Additionally, a comprehensive characterization of the membrane protein component of biomimetics utilized in this strategy is provided. Interfacing cell-derived nanomaterials with multiplexed quantitative proteomics allow for a specific targeting strategy of virulence factors that can be utilized for drug discovery against prominent human diseases.

    View details for PubMedID 28892626

  • Even Hard-Sphere Colloidal Suspensions Display Fickian Yet Non-Gaussian Diffusion ACS NANO Guan, J., Wang, B., Granick, S. 2014; 8 (4): 3331-3336


    We scrutinize three decades of probability density displacement distribution in a simple colloidal suspension with hard-sphere interactions. In this index-matched and density-matched solvent, fluorescent tracer nanoparticles diffuse among matrix particles that are eight times larger, at concentrations from dilute to concentrated, over times up to when the tracer diffuses a few times its size. Displacement distributions of tracers, Gaussian in pure solvent, broaden systematically with increasing obstacle density. The onset of non-Gaussian dynamics is seen in even modestly dilute suspensions, which traditionally would be assumed to follow classic Gaussian expectation. The findings underscore, in agreement with recent studies of more esoteric soft matter systems, the prevalence of non-Gaussian yet Fickian diffusion.

    View details for DOI 10.1021/nn405476t

    View details for Web of Science ID 000334990600023

    View details for PubMedID 24646449

  • Bursts of Active Transport in Living Cells PHYSICAL REVIEW LETTERS Wang, B., Kuo, J., Granick, S. 2013; 111 (20)


    We show, using a large new data set, that the temporally resolved speed of active cargo transport in living cells follows a scaling law over several decades of time and length. The statistical regularities display a time-averaged shape that we interpret to reflect stress buildup, followed by rapid release. The scaling power law agrees quantitatively with those reported in inanimate systems (jammed colloids and granular media, and magnetic Barkhausen noise), suggesting a common origin in pushing through a crowded environment in a weak force regime. The implied regulation of the speed of active cellular transport due to environmental obstruction results in bursts of speed and acceleration. These findings extend the classical notion of molecular crowding.

    View details for DOI 10.1103/PhysRevLett.111.208102

    View details for Web of Science ID 000327243600026

    View details for PubMedID 24289710

  • Diagnosing Heterogeneous Dynamics in Single-Molecule/Particle Trajectories with Multiscale Wavelets ACS NANO Chen, K., Wang, B., Guan, J., Granick, S. 2013; 7 (10): 8634-8644


    We describe a simple automated method to extract and quantify transient heterogeneous dynamical changes from large data sets generated in single-molecule/particle tracking experiments. Based on wavelet transform, the method transforms raw data to locally match dynamics of interest. This is accomplished using statistically adaptive universal thresholding, whose advantage is to avoid a single arbitrary threshold that might conceal individual variability across populations. How to implement this multiscale method is described, focusing on local confined diffusion separated by transient transport periods or hopping events, with three specific examples: in cell biology, biotechnology, and glassy colloid dynamics. The discussion is generalized within the framework of continuous time random walk. This computationally efficient method can run routinely on hundreds of millions of data points analyzed within an hour on a desktop personal computer.

    View details for DOI 10.1021/nn402787a

    View details for Web of Science ID 000326209100033

    View details for PubMedID 23971739

  • Modular Stitching To Image Single-Molecule DNA Transport JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Guan, J., Wang, B., Bae, S. C., Granick, S. 2013; 135 (16): 6006-6009


    For study of time-dependent conformation, all previous single-molecule imaging studies of polymer transport involve fluorescence labeling uniformly along the chain, which suffers from limited resolution due to the diffraction limit. Here we demonstrate the concept of submolecular single-molecule imaging with DNA chains assembled from DNA fragments such that a chain is labeled at designated spots with covalently attached fluorescent dyes and the chain backbone with dyes of different color. High density of dyes ensures good signal-to-noise ratio to localize the designated spots in real time with nanometer precision and prevents significant photobleaching for long-time tracking purposes. To demonstrate usefulness of this approach, we image electrophoretic transport of λ-DNA through agarose gels. The unexpected pattern is observed that one end of each molecule tends to stretch out in the electric field while the other end remains quiescent for some time before it snaps forward and the stretch-recoil cycle repeats. These features are neither predicted by prevailing theories of electrophoresis mechanism nor detectable by conventional whole-chain labeling methods, which demonstrate pragmatically the usefulness of modular stitching to reveal internal chain dynamics of single molecules.

    View details for DOI 10.1021/ja4020138

    View details for Web of Science ID 000318204800019

    View details for PubMedID 23570269

  • Automated Single-Molecule Imaging To Track DNA Shape LANGMUIR Guan, J., Wang, B., Granick, S. 2011; 27 (10): 6149-6154


    We describe a straightforward, automated line tracking method to visualize linear macromolecules as they rearrange shape by brownian diffusion and under external fields such as electrophoresis. The analysis, implemented here with 30 ms time resolution, identifies contour lines from one end of the molecule to the other without attention to structure smaller than the optical resolution. There are three sequential stages of analysis: first, "feature finding" to discriminate signal from noise; second, "line tracking" to approximate those shapes as lines; and third, "temporal consistency check" to discriminate reasonable from unreasonable fitted conformations in the time domain. Automation makes it straightforward to accumulate vast quantities of data while excluding the unreliable parts of it. We implement this analysis on fluorescence images of λ-DNA molecules in agarose gel to demonstrate its capability to produce large data sets for subsequent statistical analysis.

    View details for DOI 10.1021/la200433r

    View details for Web of Science ID 000290292900050

    View details for PubMedID 21510676

  • Single-Molecule Methods in Polymer Science JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS Granick, S., Bae, S. C., Wang, B., Kumar, S., Guan, J., Yu, C., Chen, K., Kuo, J. 2010; 48 (24): 2542-2543

    View details for DOI 10.1002/polb.22133

    View details for Web of Science ID 000284228300003

  • Confining Potential when a Biopolymer Filament Reptates PHYSICAL REVIEW LETTERS Wang, B., Guan, J., Anthony, S. M., Bae, S. C., Schweizer, K. S., Granick, S. 2010; 104 (11)


    Using single-molecule fluorescence imaging, we track Brownian motion perpendicular to the contour of tightly entangled F-actin filaments and extract the confining potential. The chain localization presents a small-displacement Hookean regime followed by a large amplitude regime where the effective restoring force is independent of displacement. The implied heterogeneity characterized by a distribution of tube width is modeled.

    View details for DOI 10.1103/PhysRevLett.104.118301

    View details for Web of Science ID 000275802600045

    View details for PubMedID 20366503

  • Stepwise interfacial self-assembly of nanoparticles via specific DNA pairing PHYSICAL CHEMISTRY CHEMICAL PHYSICS Wang, B., Wang, M., Zhang, H., Sobal, N. S., Tong, W., Gao, C., Wang, Y., Giersig, M., Wang, D., Moehwald, H. 2007; 9 (48): 6313-6318


    In the present work, we succeeded in alternatively depositing inorganic nanoparticles and functionalized DNA bases onto the water/oil interface from the water and oil bulk phases. The ligands used were functional thymines and adenines. Their thiol and phosphate groups were used to cap inorganic nanoparticles and their thymine and adenine groups to alter the surface functionality of the nanoparticles, thus enabling a layer-by-layer growth fashion of nanoparticles at the interface. The multiple particle ligation rendered the resulting nanoparticle films rather mechanically robust. As results, the freestanding asymmetric bilayer and trilayer films, composed of negatively-charged Au, positively-charged CdTe, and/or organic Ag nanoparticles were constructed; their areas were as large as over several centimetres, depending on the sizes of the containers used. Our work should bring up a novel methodology to generate asymmetric multilayer films of nanoparticles with a defined control of electron or charge across the films.

    View details for Web of Science ID 000251441100004

    View details for PubMedID 18060160

  • Chitosan-mediated synthesis of gold nanoparticles on patterned poly(dimethylsiloxane) surfaces BIOMACROMOLECULES Wang, B., Chen, K., Jiang, S., Reincke, F., Tong, W. J., Wang, D. Y., Gao, C. Y. 2006; 7 (4): 1203-1209


    Synthesis of gold nanoparticles on surfaces has been accomplished by the incubation of poly(dimethylsiloxane) (PDMS) films in tetrachloroauric(III) acid and chitosan solution at room temperature and 4 degrees C. One important point in the present study is that the synthesis selectively occurred on the PDMS surface. These observations are substantially different from the reaction in solution, in which no particles can be formed at room temperature. Computation of surface plasmon bands (SPBs) based on Mie theory suggests that the particles are partially coated by chitosan molecules, and the experimental results confirm the theoretical calculations. The proposed mechanism is that chitosan molecules adsorbed or printed on the PDMS surfaces act as reducing/stabilizing agents. Furthermore, PDMS films patterned with chitosan could induce localized synthesis of gold nanoparticles in regions capped with chitosan only. In this way, colloidal patterns were fabricated on the surfaces with high spatial selectivity simultaneously with the synthesis of the particles. Surface-induced fluorescence quenching was observed in the regions capped with gold nanoparticles as well.

    View details for DOI 10.1021/bm060030f

    View details for Web of Science ID 000236868800027

    View details for PubMedID 16602739

  • Compression-inhibited pore formation of polyelectrolyte multilayers containing weak polyanions: A scanning force microscopy study CHEMPHYSCHEM Wang, B., Liu, L. L., Ke, C., Chen, L., Feng, J., Gao, C. Y. 2006; 7 (3): 590-596


    Morphological changes of poly(acrylic acid)/poly(diallyldimethylammonium chloride) multilayers induced by low pH were investigated by scanning force microscopy. The weakened interaction between the charged polymer chains in the protonation process is believed to be the reason for this variation. Kinetic studies have shown that during protonation phase separation and dissociation of the multilayers took place successively. The compression of the multilayers, however, caused a transition of the multilayers from a rubbery state to a glassy state. As a result, the closely compacted multilayers lost their sensitivity to pH change. An increase of electrostatic and hydrophobic interactions, can decrease the free energy of the multilayers, and stabilize the films. By compression of the multilayers with a rubber stamp having geometric patterns, films with spatially localized pores were produced.

    View details for DOI 10.1002/cphc.200500369

    View details for Web of Science ID 000236300600010

    View details for PubMedID 16425342

  • Biologically driven assembly of polyelectrolyte microcapsule patterns to fabricate microreactor arrays ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Wang, B., Zhao, Q. H., Wang, F., Gao, C. Y. 2006; 45 (10): 1560-1563

    View details for DOI 10.1002/anie.200502822

    View details for Web of Science ID 000235752600009

    View details for PubMedID 16440395

  • Loading and release behaviors of compressed polyelectrolyte multilayers for small dye molecules JOURNAL OF PHYSICAL CHEMISTRY B Wang, B., Gao, C. Y., Liu, L. L. 2005; 109 (11): 4887-4892


    Loading and release behaviors of compressed polyelectrolyte multilayers composed of poly(styrenesulfonate sodium salt) and poly(diallyldimethylammonium chloride) were investigated using fluorescein and rhodamine 6G as indicators by confocal laser scanning microcopy, fluorescence spectroscopy, and UV-vis spectroscopy. Compression of the multilayers resulted in a more densely packed microstructure, leading to the decrease of fluorescence intensity of the incorporated probes to 80% of its initial value, and much slower releasing rate as well as smaller releasing amount regardless of the types of the probes and the presence of salt. Utilizing the difference of loading and release rates between the compressed and the uncompressed regions, arrays of dye reservoirs have been fabricated on a chemical homogeneous but physical heterogeneous multilayer film.

    View details for DOI 10.1021/jp0450282

    View details for Web of Science ID 000227734500013

    View details for PubMedID 16863143

  • Physical-co-chemical multicomponent micropatterns on polymer surfaces by thermal pressing method CHEMISTRY OF MATERIALS Wang, B., Feng, J., Gao, C. Y. 2004; 16 (24): 4859-?

    View details for DOI 10.1021/cm049156e

    View details for Web of Science ID 000225365800004

  • Irreversible compression of polyelectrolyte multilayers MACROMOLECULES Gao, C. Y., Wang, B., Feng, J., Shen, J. C. 2004; 37 (24): 8836-8839

    View details for DOI 10.1021/ma048930g

    View details for Web of Science ID 000225371200008

  • Selective adsorption of microcapsules on patterned polyelectrolyte multilayers ADVANCED MATERIALS Feng, J., Wang, B., Gao, C. Y., Shen, J. C. 2004; 16 (21): 1940-?