Indian Institute of Technology Guwahati

About: Indian Institute of Technology Guwahati is a education organization based out in Guwahati, Assam, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 6933 authors who have published 17102 publications receiving 257351 citations.

3D Printed Cartilage-Like Tissue Constructs with Spatially Controlled Mechanical Properties

Abstract: Developing biomimetic cartilaginous tissues that support locomotion while maintaining chondrogenic behavior is a major challenge in the tissue engineering field. Specifically, while locomotive forces demand tissues with strong mechanical properties, chondrogenesis requires a soft microenvironment. To address this challenge, 3D cartilage-like tissue is bioprinted using two biomaterials with different mechanical properties: a hard biomaterial to reflect the macromechanical properties of native cartilage, and a soft biomaterial to create a chondrogenic microenvironment. To this end, a hard biomaterial (MPa order compressive modulus) composed of an interpenetrating polymer network (IPN) of polyethylene glycol (PEG) and alginate hydrogel is developed as an extracellular matrix (ECM) with self-healing properties, but low diffusive capacity. Within this bath supplemented with thrombin, fibrinogen containing human mesenchymal stem cell (hMSC) spheroids is bioprinted forming fibrin, as the soft biomaterial (kPa order compressive modulus) to simulate cartilage's pericellular matrix and allow a fast diffusion of nutrients. The bioprinted hMSC spheroids improve viability and chondrogenic-like behavior without adversely affecting the macromechanical properties of the tissue. Therefore, the ability to print locally soft and cell stimulating microenvironments inside of a mechanically robust hydrogel is demonstrated, thereby uncoupling the micro- and macromechanical properties of the 3D printed tissues such as cartilage.

Reversible encapsulation of nanometer-size polyaniline and polyaniline-Au-nanoparticle composite in starch

Abstract: In this paper we report a new method of solubilization of polyaniline and polyaniline-Au-nanoparticle composite by encapsulating nanometer-size particles in starch The solubilization was carried out in the presence of ultrasonic waves We also report that the encapsulation was completely reversible and the dissolved polyaniline as well as the composite could be recovered by replacement with molecular iodine In addition, the polymer particles could also replace molecular iodine from starch-iodine complex UV-Visible and Fourier transform infrared (FTIR) spectroscopic measurements established the reversible nature of encapsulation Transmission electron microscopic measurements showed that the sizes of the particles encapsulated in starch were on the order of 10-20 nm for both polyaniline and Au-nanoparticle-polyaniline composite particles X-ray diffraction evidenced the presence ofAu-nanoparticles in the starch-polyaniline-Au-nanoparticle composite Finally, we also mention here that the dissolved polyaniline could also be recovered as a precipitate by enzyme (diastage) hydrolysis of the polyaniline encapsulating starch

Sustainable materials for 3D concrete printing

Abstract: This paper explores the sustainability aspects of binders used in concrete 3D concrete printing. Firstly, a prospective approach to conduct sustainability-assessment based on the life cycle of 3D printed structures is presented, which also highlights the importance of considering the functional requirements of the mixes used for 3D printing. The potential of the material production phase is emphasized to enhance the sustainability potential of 3DCP by reducing the embodied impacts. The literature on the different binder systems used for producing 3D printable mixtures is reviewed. This review includes binders based on portland cement and supplementary cementing materials (SCMs) such as fly ash, silica-fume and slag. Also, alternative binders such as geopolymer, calcium sulfo-aluminate cement (CSA), limestone calcined clay cement (LC3) and reactive magnesium oxide systems are explored. Finally, sustainability assessment by quantifying the environmental impacts in terms of energy consumed and CO2 emissions of mixtures is illustrated with different binder systems. This paper underlines the effect of using SCMs and alternative binder systems for improving the sustainability of 3D printed structures.

Post-synthetic modification of a metal-organic framework with fluorescent-tag for dual naked-eye sensing in aqueous medium

Abstract: The existing metal-organic framework (MOF) called UiO-66-NH 2 ( 1 ; UiO = University of Oslo) was post-synthetically modified by condensation with 1-pyrenecarboxaldehyde. The pyrene-tagged MOF ( 1′ ) exhibited ∼3-fold enhancement in fluorescence intensity over the un-functionalized one with a new emission peak at 470 nm due to the formation pyrene excimer within the framework of the MOF. 1′ showed fast response time, excellent selectivity and sensitivity for sensing of biologically active anions like F − and H 2 PO 4 − in pure aqueous medium via fluorescence ‘turn-on’ mechanism with detection limits of 8.2 × 10 −7 M and 7.3 × 10 −7 M, respectively. The fluorescence enhancement and the distinctive blue shifts in the emission bands of 1′ in presence of the anions are attributed to strong hydrogen bonding interactions and static pyrene excimer formation, respectively. 1′ also displayed rapid, selective and sensitive detection of 2,4,6-trinitrophenol (TNP) in aqueous medium via fluorescence ‘turn-off’ mechanism with a detection limit of 2.1 × 10 −7 M. The highly selective fluorescence quenching is ascribed to electron and energy transfer processes as well as molecular interactions (π-π and electrostatic) of the MOF with TNP. The excellent detection performance of 1′ in aqueous medium makes it a promising dual sensor material for real-field applications.