Shubin Li’s research while affiliated with Harbin Institute of Technology and other places

In a crowded environment, macromolecules occupy a significant proportion volume of cells to repulse other molecules in H2O‐rich phase domains. These H2O‐rich phase domains have been found to significantly influence material transportation and biochemical reactions. However, the accurate quantification of the size of these domains remains a challenge. Here, formulas are set up to calculate the anomalous diffusion exponent (α), the concentration threshold (cp), and the radius of the H2O‐rich phase domain (r0) to characterize the crowded solutions. Fitting coefficient (R²) of the r0 fitted curves are 0.9989 for PEG‐8k Da and 0.9901 for PEG‐20k Da, respectively, which confirms the formulas to be suitable for quantifying the crowding degree. The values of α, r0, and cp of three different cell lysates is are calculated using these formulas. The r0 values of the cytosol from eukaryotic cells are 1.22 µm for HEK‐293T and 1.46 µm for S. Cerevisiae, respectively, which are smaller than that (2.13 µm) from prokaryotic cells (E. coli). This may be due to the more complex components, with higher molecular weight but lower concentration in the eukaryotic cells. This method for quantifying the H2O‐rich phase in a crowded solution helps to have a deeper understanding of the biochemical mechanism inside cells.

Building an artificial photosynthetic cell from scratch helps to understand the working mechanisms of chloroplasts. It is a challenge to achieve carbon fixation triggered by photosynthetic organelles in an artificial cell. ATP synthase and photosystem II (PSII) are purified and reconstituted onto the phospholipid membrane to fabricate photosynthetic organelles. With the integration of phycocyanin, the ATP production yield increases by 2.51‐fold due to the enhanced light harvesting capability. The carbon fixation pathway is established by converting α‐oxoglutarate to acetyl‐CoA and oxaloacetate with cascade enzyme reactions including the isocitrate dehydrogenase (IDH), aconitase (ACO), and ATP citrate lyase (ACL). The photosynthetic organelles, phycocyanin, and carbon fixation pathway are encapsulated into giant unilamellar vesicles to obtain artificial photosynthetic cells, which convert α‐oxoglutarate to acetyl‐CoA and oxaloacetate inside artificial cells upon light irradiation. The acetyl‐CoA is the most important intermediate product in the cellular metabolic networks for the synthesis of cholesterol and fatty acids. Our results provide a way for efficient light energy conversion to produce ATP and fix CO2, and pave the path to build autonomous artificial cells with more complicated metabolic networks.

Building an artificial photosynthetic cell from scratch helps to understand the working mechanisms of chloroplasts. It is a challenge to achieve carbon fixation triggered by photosynthetic organelles in an artificial cell. ATP synthase and photosystem II (PSII) are purified and reconstituted onto the phospholipid membrane to fabricate photosynthetic organelles. With the integration of phycocyanin, the ATP production yield increases by 2.51‐fold due to the enhanced light harvesting capability. The carbon fixation pathway is established by converting α‐oxoglutarate to acetyl‐CoA and oxaloacetate with cascade enzyme reactions including the isocitrate dehydrogenase (IDH), aconitase (ACO), and ATP citrate lyase (ACL). The photosynthetic organelles, phycocyanin, and carbon fixation pathway are encapsulated into giant unilamellar vesicles to obtain artificial photosynthetic cells, which convert α‐oxoglutarate to acetyl‐CoA and oxaloacetate inside artificial cells upon light irradiation. The acetyl‐CoA and oxaloacetate are the most important intermediate products in the cellular metabolic networks for the synthesis of cholesterol and fatty acids. Our results provide a way for efficient light energy conversion to produce ATP and fix CO2, and pave the path to build autonomous artificial cells with more complicated metabolic networks.

Constructing a synthetic community system helps scientist understand the complex interactions among species in a community and its environment. Herein, a two-species community is constructed with species A (artificial cells encapsulating pH-responsive molecules and sucrose) and species B (Saccharomyces cerevisiae), which causes the environment to exhibit pH oscillation behaviour due to the generation and dissipation of CO2. In addition, a three-species community is constructed with species A′ (artificial cells containing sucrose and G6P), species B, and species C (artificial cells containing NAD⁺ and G6PDH). The solution pH oscillation regulates the periodical release of G6P from species A′; G6P then enters species C to promote the metabolic reaction that converts NAD⁺ to NADH. The location of species A′ and B determines the metabolism behaviour in species C in the spatially coded three-species communities with CA′B, CBA′, and A′CB patterns. The proposed synthetic community system provides a foundation to construct a more complicated microecosystem.

The bottom‐up constructed artificial cells help to understand the cell working mechanism and provide the evolution clues for organisms. The energy supply and metabolism mimicry are the key issues in the field of artificial cells. Herein, an artificial cell containing cyanobacteria capable of light harvesting and carbon dioxide fixation is demonstrated to produce glucose molecules by converting light energy into chemical energy. Two downstream “metabolic” pathways starting from glucose molecules are investigated. One involves enzyme cascade reaction to produce H2O2 (assisted by glucose oxidase) first, followed by converting Amplex red to resorufin (assisted by horseradish peroxidase). The other pathway is more biologically relevant. Glucose molecules are dehydrogenated to transfer hydrogens to nicotinamide adenine dinucleotide (NAD⁺) for the production of nicotinamide adenine dinucleotide hydride (NADH) molecules in the presence of glucose dehydrogenase. Further, NADH molecules are oxidized into NAD⁺ by pyruvate catalyzed by lactate dehydrogenase, meanwhile, lactate is obtained. Therefore, the cascade cycling of NADH/NAD⁺ is built. The artificial cells built here pave the way for investigating more complicated energy‐supplied metabolism inside artificial cells.

As the most abundant natural polymer on the planet, cellulose has a wide range of applications in the biomedical field. Cellulose-based hydrogels further expand the applications of this class of biomaterials. However, a number of publications and technical reports are mainly about traditional preparation methods. Sonochemistry offers a simple and green route to material synthesis with the biomedical application of ultrasound. The tiny acoustic bubbles, produced by the propagating sound wave, enclose an incredible facility where matter interact among at energy as high as 13 eV to spark extraordinary chemical reactions. Ultrasonication not only improves the efficiency of cellulose extraction from raw materials, but also influences the hydrogel preparation process. The primary objective of this article is to review the literature concerning the biomedical cellulose-based hydrogel prepared via sonochemistry and application of ultrasound for hydrogel. An innovated category of recent generations of hydrogel materials prepared via ultrasound was also presented in some details.