Small Molecular Substances Research Articles

Synthesis of Bi2WO6/g-C3N4 photocatalyst and high degradation of Rhodamine B under visible light irradiation

PurposeThe purpose of this paper is to improve the degradation efficiency of Rhodamine B (RhB) by new photocatalytic materials.Design/methodology/approachBinary Z-scheme g-C3N4/Bi2WO6 photocatalytic material was synthesized by the one-step hydrothermal reaction. The construction of Z-scheme heterojunction led to the rapid separation of photogenerated electrons and holes, which would degrade RhB into small molecular substances to achieve the purpose of degradation.FindingsIt was found that Bi2WO6/25%g-C3N4 displayed the highest photocatalytic activity, which was about 1.44 and 1.34 times higher than that of pure Bi2WO6 and g-C3N4, respectively. According to the trapping experiments, the superoxide radical (·O2−) was the major active species of the RhB decomposition in Bi2WO6/g-C3N4 catalysts.Originality/valueThe successful synthesis of Z-scheme Bi2WO6/g-C3N4 provides new ideas and references for the design of catalysts with high photocatalytic activity, which should have wide applications in the future.

Photocatalytic purification of contaminated air in intensive care units by ZnSn(OH)6 nanoparticles.

The air purification in intensive care units (ICU) involving the removal of smog and volatile organic compounds (VOCs), disinfection, and sterilization are closely linked to important health issues. The environmental photocatalysis technology that could decompose gaseous pollutants into small molecular inorganic substances provides the potential solution. In a chamber of 30-m3 simulated ICU, photocatalytic purifier with ZnSn(OH)6 nanoparticles photocatalyst is set up to treat 10 VOCs with concentration below 2 ppm. Compared with regular purifiers of plasma and activated carbon, the present photocatalytic purifier can completely eliminate 10 varieties of low-concentration irritating VOCs without CO production. The continuous tests show that loading of 600 g ZnSn(OH)6 has capacity to treat large volumes of VOCs and remains high removal efficiencies up to 600-h operation. The results suggest that the photocatalytic purifier could be potentially applied for the treatment of contaminated indoor air particularly ICU. The mechanism of ZnSn(OH)6 photocatalysis is proposed to interpret the high performance and mineralization of the degradation process.

Synergistic interactions for saving energy and promoting the co-pyrolysis of polylactic acid and wood flour

The rapid growth of polylactic acid (PLA) production and the slow hydrolysis rate make PLA a potential environmental pollutant. In order to make better reuse of the waste PLA in energy fields and solve the potential pollutant, PLA/wood flour (WF) compounds in all different proportions were co-pyrolyzed to study the co-pyrolysis behavior in terms of energy and products. The apparent activation energy of the 50%wtWF50%wtPLA compounds during co-pyrolysis decreased by 28% than PLA and 29.4% than WF. In addition, the pyrolysis of PLA provided additional energy for the co-pyrolysis of compounds which reduced the external input energy. The chemical reactions between WF and PLA during co-pyrolysis could be called synergistic interactions which promoted the free radical reaction of PLA and lead to the increase of lactide production. The yield of the harmful acetaldehyde reduced by 85.9% in the co-pyrolysis of 25%wtWF75%wtPLA compounds. In addition, the production of small molecular benzene ring substances was increased. For example, the phenol yield increased by 31.3% in the co-pyrolysis of 25%wtWF75%wtPLA compounds. The carbon number distribution of the main products was mainly concentrated on C5–C7 which was better for the reuse of bio-fuels during co-pyrolysis.

Effect of Fe-based catalytic ozonation and sole ozonation on the characteristics and conversion of organic fractions in bio-treated industrial wastewater

The conversion of hydrophobic (HPO)/transphilic (TPI)/hydrophilic (HPI) fractions of dissolved effluent organic matter (EfOM) in water by sole ozonation process (SOP) and catalytic ozonation process (COP) were investigated in this study. The modified iron shavings were used as catalyst in COP. The difference in total organic carbon (TOC) removal rate between SOP and COP for two types of bio-treated industrial wastewater was mainly caused by the different HPI degradation degree. The accumulation of HPI in SOP was 28.8% (in bio-treated dyeing wastewater) and 88.8% (in bio-treated paper-making wastewater) higher than that in COP, while HPO was degraded by more than 90% in both processes. Part of HPO was converted to TPI in the early stage (0–15 min) and the original HPI in the raw water was degraded at the same time. In the middle stage (15–60 min), TPI was transformed into HPI. The remaining fluorescent substances in HPI fraction in SOP were higher than those in COP, indicating that more HPI was accumulated in SOP. Among the fluorescent substances, aromatic protein II and SMP-like substances were removed more completely, while humic acid-like substances were relatively more difficult to degrade. Furthermore, COP had higher removal for fulvic acid-like substances, SMP-like substances and humic acid-like substances than SOP, while the removals of aromatic protein by COP and SOP were almost the same. COP had better removal effect than SOP for TPI and HPI organic pollutants with molecular weight (MW) more than 2 kDa. SOP and COP had no significant difference in the removal of HPO fraction and small molecular organics with MW less than 2 kDa. The remaining organic pollutants in the effluent of COP was mainly hydrophilic small molecular substances, which would be benefit for secondary biochemical process.

Study on the ozone aging mechanism of Natural Rubber

Regarded as a strategically crucial material, natural rubber (NR) plays an essential role in our daily life. However, the corresponding rubber products have been facing the problem of aging in which the ozone aging of natural rubber accounts for a crucial position. Based on the concern, the related mechanism of ozone aging for natural rubber was systematically studied in this work. Besides, to deeply understand the mechanism of ozone aging, we selected squalene, a small molecular substance with similar structure to natural rubber, to simulate the ozone aging process and analyze the molecular structure changes of natural rubber. After comprehensive characterization, the obtained results showed that the natural rubber molecular network, during the aging process, was destroyed and three newly-discovered free radicals were generated (•H, •O2−and •C=C), finally resulting in the weakened mechanical properties. We believe this work can provide a more insightful view toward the relevant research on the ozonolysis mechanism and the relationship between structure and performance as well as new ideas for the design of high-efficiency antioxidants for NR.

Enhanced paraquat removal from contaminated water using cell-immobilized biochar

The efficient performance of cell-immobilized biochar in removing paraquat (PQ) from contaminated water is described in this work. Pseudomonas putida was immobilized onto coconut fiber-derived biochar (BC) using the adsorption method and the covalent binding method. The FTIR spectrum analysis revealed that the main adsorption mechanism of bacteria and BC relates to the interaction between cell surface proteins and the functional group on biochar. The pseudo-second-order model could explain the kinetics of simultaneous adsorption and biodegradation of cell immobilization on BC. Cell-immobilized biochar using the covalent bonding method and adsorption method exhibited superior PQ removal capacity with 30–35% increases in efficiency compared with simple biochar. After 48 h using cell-immobilized biochar, the PQ was transformed to 4,4-bipyridyl and malic acid as detected by GC/MS. From the PQ kinetic removal rate and bacterial retention, the covalent binding method with 16.79 mg/g paraquat adsorption capacity and 0.626 g/mg/h kinetic rate constant is considered as the best cell-immobilization method for the immobilization technique. The cell immobilization on biochar using both the adsorption method and the covalent binding method can support bacteria to degrade PQ into small molecular substances in water treatment processes.

Lipoproteins in chronic kidney disease: from bench to bedside.

Chronic kidney disease (CKD) is associated with high cardiovascular risk. CKD patients exhibit a specific lipoprotein pattern termed 'uraemic dyslipidaemia', which is characterized by rather normal low-density lipoprotein cholesterol, low high-density lipoprotein cholesterol, and high triglyceride plasma levels. All three lipoprotein classes are involved in the pathogenesis of CKD-associated cardiovascular diseases (CVDs). Uraemia leads to several modifications of the structure of lipoproteins such as changes of the proteome and the lipidome, post-translational protein modifications (e.g. carbamylation) and accumulation of small-molecular substances within the lipoprotein moieties, which affect their functionality. Lipoproteins from CKD patients interfere with lipid transport and promote inflammation, oxidative stress, endothelial dysfunction as well as other features of atherogenesis, thus contributing to the development of CKD-associated CVD. While, lipid-modifying therapies play an important role in the management of CKD patients, their efficacy is modulated by kidney function. Novel therapeutic agents to prevent the adverse remodelling of lipoproteins in CKD and to improve their functional properties are highly desirable and partially under development.

Polyphenols in fermented apple juice: Beneficial effects on human health

• Factors affecting the polyphenol composition of fermented apple juice were presented. • Polyphenols are mainly converted into small-molecule active substances by induced enzyme. • The effect of fermented apple juice on non-communicable diseases were reviewed. • These small molecular weight active substances could help prevent CVD and T2DM. Chronic non-communicable diseases are one of the major human health challenges in the 21st century. Fermented apple juice rich in polyphenols has a beneficial effect on the prevention of non-communicable diseases. This review illustrates that the fermentation process involved in biotransformation significantly changes the composition and content of polyphenols in cloudy apple juice related to apple varieties, fermentation types, and fermentation strains. The enzymatic transformation reaction converts polyphenols into small molecules phenolic compounds with higher biologically activity. These small molecular weight active substances could help prevent cardiovascular disease and type 2 diabetes mellitus by mediating the AMPK pathway, the Nrf2 signaling pathway, the polyol pathway, and the NF-κB pathway. Moreover, this review is intended to provide a systematic theoretical basis for researchers to further study the bioactive function of fermented apple juice for the first time.

Characterisation and antioxidant activity of glycated casein hydrolysate with xylose: Impacts of zinc sulphate and cupric chloride

Impacts of zinc sulphate and cupric chloride on characteristics and antioxidant capacities of glycated products (GPs) derived from casein hydrolysate (CH) and xylose were studied. The browning degree of xylose–CH GPs was the largest at zinc sulphate addition of 15 mg L−1, while its browning degree increased with cupric chloride extended from 0 to 15 mg L−1. Loss of free amino groups, fluorescence intensity and the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging capacity of xylose–CH GPs increased with the increase of cupric chloride addition, but loss of amino groups, fluorescence intensity and DPPH radical scavenging capacity were largest at the zinc sulphate addition of 15 mg L−1. The addition of zinc sulphate and cupric chloride promoted production of higher and smaller molecular substances in xylose–CH GPs and CH. Therefore, zinc sulphate and cupric chloride promoted glycated reaction of xylose and CH and enhanced antioxidant activity of xylose–CH GPs.

Extraneous Fe Increased the Carbon Retention of Sludge-Based Biochar.

Pyrolysis is a promising technology for the disposal of sewage sludge. In this study, FeCl3 was selected as an additive for sludge pyrolysis. The results indicated that the FeCl3-addition strategy not only enhanced carbon retention but also enhanced the nitrogen retention of sludge-based biochar. The best enhancement effect both occurred at 500°C, and the enhanced amount reached 29.7mg C/g sludge and 1.33mg N/g sludge, respectively. This enhancement may be attributed to the physical isolation provided by newly formed metallic complexes or oxides. Besides, the added FeCl3 improved the polarity and aromaticity of modified biochar by retaining more oxygen-containing functional groups, and could also catalyze the decomposition of tar, resulting in the release of more small molecular substances. The quantitative estimation of carbon and nitrogen retention in provinces of China found that the enhancement in coastal provinces was significantly preceded that of inland provinces.

Recommendations when switching therapy from immunosuppressive drugs to dupilumab in patients with atopic dermatitis

Basierend auf neuen Erkenntnissen zur molekularen Pathogenese der atopischen Dermatitis, wurde neben Glukokortikoiden und Ciclosporin mit Dupilumab nun auch eine zielgerichtete antientzündliche Systemtherapie zugelassen. Wegen ihrer Pharmakologie sind weder Glukokortikoide und Ciclosporin noch die außerhalb der Zulassung angewendeten Substanzen Methotrexat, Azathioprin und Mycophenolsäurederivate für eine Langzeittherapie geeignet. Bei der Umstellung der Therapie von den genannten niedermolekularen Substanzen auf Dupilumab sollten verschiedene Faktoren berücksichtigt werden. Hierbei sind sowohl der konkrete Anlass der Umstellung (Unwirksamkeit, unerwünschte Wirkungen oder sich einstellende Kontraindikationen) als auch die pharmakologischen Gegebenheiten zu berücksichtigen. Da es hierzu bisher keine konkreten klinischen Untersuchungen gibt, haben die Autoren auf der Grundlage einer Literaturrecherche Handlungsempfehlungen für den praktischen Alltag erarbeitet.

Advances in application of capillary electrophoresis in pharmaceutical analysis

Capillary electrophoresis (CE) is mainly applied in pharmaceutical analysis. All CE separation modes and detection methods show their characteristics and application abilities in the separation and analysis of different drug samples. The present review provides a brief cross section of new advances in CE application in pharmaceutical analysis, including for small molecular drugs and related substances (including chiral drug separation), traditional Chinese medicine and natural products, in vivo pharmaceutical analysis, and biological product analysis. However, the research on physical and chemical constant determination, affinity capillary electrophoresis and binding constant research (drug and receptor interaction, etc.), clinical biomarker analysis, metabolomics, and microchip CE analysis are not included. According to traditional pharmaceutical analysis developments, the recent advances in CE in compliance with pharmaceutical analysis regulatory requirements include CE capacitively coupled contactless conductivity detection (C4D), improved detection sensitivity and precision, CE-sodium dodecyl sulfate (CE-SDS), imaged capillary isoelectric focusing (icIEF), antibody analysis, and so on. Combined with the references, this review also discusses the current requirements in the field of traditional pharmaceutical analysis, as well as the status, challenges and opportunities of CE in it. Some suggestions on CE application as a complementary analysis method for chemical drugs and traditional Chinese medicine analysis are put forward, and the characteristics and ability of CE in biological product analysis is expected to further development. The new development of CE-MS and improvement of CE repeatability may greatly expand the field of application of CE in the future. This review covers the improvements published between January 2017 and February 2020, as well as some important CE papers published in 2016.

Design and Fabrication of Dual Redox Responsive Nanoparticles with Diselenide Linkage Combined Photodynamically to Effectively Enhance Gene Expression.

BackgroundPEI is currently the most used non-viral gene carrier and the transfection efficiency is closely related to the molecular weight; however, the prominent problem is that the cytotoxicity increased with the molecular weight.MethodsA novel redox responsive biodegradable diselenide cross-linked polymer (dPSP) was designed to enhance gene expression. ICG-pEGFP-TRAIL/dPSP nanoparticles with high drug loading are prepared, which have redox sensitivity and plasmid protection. The transfection efficiency of dPSP nanoparticle was evaluated in vitro.ResultsThe plasmid was compressed by 100% at the N/P ratio of 16, and the particle size was less than 100 nm. When explored onto high concentrations of GSH/H2O2, dPSP4 degraded into small molecular weight cationic substances with low cytotoxicity rapidly. Singlet oxygen (1O2) was produced when indocyanine green (ICG) was irradiated by near-infrared laser irradiation (NIR) to promote oxidative degradation of dPSP4 nanoparticles. Under the stimulation of NIR 808 and redox agent, the particle size and PDI of ICG-pDNA/dPSP nanoparticle increased significantly.ConclusionCompared with gene therapy alone, co-transportation of dPSP4 nanoparticle with ICG and pEGFP-TRAIL had better antitumor effect. Diselenide-crosslinked polyspermine had a promising prospect on gene delivery and preparation of multifunctional anti-tumor carrier.

Impact of monovalent cations on the separation performance of graphene oxide membrane for different organic matters.

Graphene oxide (GO) membrane has become a promising membrane due to its advantages of high flux, good anti-pollution performance, and controllable cost. Since wastewater contains inorganic ions and organic substances, the effect of inorganic ions on the removal of organic matters has attracted attention. This study investigated the impact of monovalent cations (Na+ and K+) on the removal of different organic matters by GO membranes. The results showed that the removal by GO membranes of both macromolecular organic compounds (humic acid, sodium alginate, and bull serum albumin) and small molecular organic substances (new coccine, methyl orange, and methylene blue) were high (>75%). The coexisting Na+ caused the increase in flux and the decrease in removal of small molecular organic matters, while the impact on the removal of macromolecular organic matters was weak. The impact of the coexisting K+ was weaker than Na+. With the crosslinking of ethylenediamine, the structure of GO membrane was more stable. The impacts of Na+ on the flux and separation performance of crosslinked membranes were less than that of non-crosslinked membranes. This suggests that crosslinked GO membrane has more potential for practical wastewater treatment.

Ultrasensitive aptamer-based biosensor for acetamiprid using tetrahedral DNA nanostructures

An electrochemical tetrahedral APT biosensor (Au-TAN biosensor) was successfully constructed, which had a stable structure and excellent performance using tetrahedral DNA nanomaterials (TDN) and Au nanoparticles (AuNPs) for the detection of acetamiprid. Specifically, we designed a partial paired complementary DNA (cDNA) of acetamiprid aptamer and inserted the cDNA together with the acetamiprid aptamer into four single-stranded DNA sequences forming each side of the TDN, modifying AuNPs to increase the current signal intensity, to assemble the Au-TAN. This proposed aptasensor was compared with ssAPT aptasensor and tetrahedral APT nanostructures (TAN) aptasensor, respectively. The results showed that the performance of the designed aptasensor was better than those of the above two aptasensors. The detection limit of the aptasensor was calculated to be 0.077 pM (S/N = 3), which was far lower than that of other methods that we compared. Under optimized conditions, the proposed aptasensor showed a wide linear detection range from 0.1 pM to 10 nM. The Au-TAN biosensor opens up new ideas for the construction of aptasensors and provides a new method for detection of small molecular substances, such as pesticides residues.

The release and removal of sludge toxicity by different disintegration methods

The increasing production of toxic sludge becomes the limiting factor of sludge resource utilization. In this study, the source of sludge toxicity and the best way for toxic organic reduction was investigated. Four disintegration methods (freeze/thaw, ultrasonication, alkali-thermal hydrolysis and ozonation) were used to analyze the release of organic matter and sludge toxicity reduction. Ultrasonication (SCOD = 5120.4 ± 67.8 mg L−1) was the best way to break sludge and remove toxicity among four methods, which dissolution rate was more than 80%, and the total toxicity inhibition rate could be reduced to 64.3 ± 4.2%, significantly reducing the toxicity of sludge. Gel chromatography (GPC) showed that the disintegration could convert refractory macromolecular organics (MW > 10 kDa) into small molecular substances (MW < 500 Da), which changed the biodegradability of sludge and improving the performance of sludge resource utilization. The relative inhibition rate of luminescent bacteria found that pretreatments could reduce the organic toxicity of sludge, which was mainly derived from organic matter of 5 kDa < MW < 10 kDa. The 3D-EEMs analysis of 5 -10 kDa organics revealed that disintegration increased the fluorescence intensity of aromatic protein species (peaks I and II), and there were significant differences in the fluorescence region of soluble microbial products (peak III), of which part ultrasonication can reduce the intensity. Thus, ultrasonication can play an important role in reducing toxic organic.

Remediation of Anthracene-Contaminated Soil with Sophorolipids-SDBS-Na2SiO3 and Treatment of Eluting Wastewater

The soil pollution of polycyclic aromatic hydrocarbons (PAHs) is serious in China, which not only affects the living and growing environment of plants and animals but also has a great impact on people’s health. The use of hydrophobic organic compounds to make use of surfactant ectopic elution processing is more convenient and cheaper as a repair scheme and can effectively wash out the polycyclic aromatic hydrocarbons in the soil. Therefore, we mixed sophorolipids:sodium dodecylbenzene sulfonate (SDBS):Na2SiO3 according to the mass ratio of 1:15:150. We explored the influencing factors of high and low concentrations of PAH-contaminated soil using a single factor test and four factors at a two-level factorial design. Then, the elution wastewater was treated by ultrasonic oxidation technology and the alkali-activated sodium persulfate technology. The results showed that: (1) In the single factor test, when the elution time is 8 h, the concentration of the compounded surfactant is 1200 mg/L, the particle size is 60 mesh, the concentration of NaCl is 100 mmol/L, and the concentration of KCl is 50 mmol/L, and the effect of the PAH-contaminated soil eluted by the composite surfactant is the best. Externally added NaCl and KCl salt ions have a more obvious promotion effect on the polycyclic aromatic hydrocarbon-contaminated soil; (2) in the interaction experiment, single factor B (elution time) and D (NaCl concentration) have a significant main effect. There is also a certain interaction between factor A (concentration agent concentration) and factor D, factor B, and factor C (KCl concentration); (3) the treatment of anthracene in the eluate by ultrasonic completely mineralizes the organic pollutants by the thermal and chemical effects produced by the ultrasonic cavitation phenomenon, so that the organic pollutants in the eluate are oxidized and degraded into simple environmentally friendly small molecular substances. When the optimal ultrasonic time is 60 min and the ratio of oxidant to activator is 1:2, the removal rate of contaminants in the eluent can reach 63.7%. At the same time, the turbidity of the eluent is significantly lower than that of the liquid after centrifugal separation, indicating that oxidants can not only remove the pollutants in elution water but also remove the residual soil particulate matter; and (4) by comparing the infrared spectrum of the eluted waste liquid before and after oxidation, it can be seen that during the oxidation process, the inner part of eluent waste liquid underwent a ring-opening reaction, and the ring-opening reaction also occurred in the part of the cyclic ester group of the surfactant, which changed from a ring to non-ring.

High throughput analysis and quantitation of α-dicarbonyls in biofluid by plasmonic nanoshells enhanced laser desorption/ionization mass spectrometry

Advanced analytical platforms are required for accurate detection and quantification of small molecular substances exhibiting certain toxicity. Small molecules detection in complex biological fluids are challenged by the complexity of the samples and the low throughput of the existing methods. In the present study, to detect a batch of samples (50) in 1 h, the plasmonic nanoshell enhanced matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) was tested. The limit of quantification (LOQ) was determined as 0.01 μg/mL (for α-dicarbonyl compounds) by vortex-assisted liquid-liquid microextraction (VALLME). The developed method can be adopted to study the high-throughput metabolomics and employed for clinical precision diagnosis with MALDI-TOF MS.

Effect of Different Passivating Agents on the Stabilization of Heavy Metals in Chicken Manure Compost and Its Maturity Evaluating Indexes

We explore the effects of different passivating agents on livestock manure treatment by using chicken manure and straw as raw materials and thermophilic rapid fermentation. We investigate the effects of sepiolite (SE), calcium magnesium phosphate fertilizer (NP), biochar (BI), compounds of sepiolite plus calcium magnesium phosphate fertilizer (S+N), sepiolite plus biochar (S+B), calcium magnesium phosphate fertilizer plus biochar (N+B), and sepiolite plus calcium magnesium phosphate fertilizer and biochar (SNB) on the physical and chemical characteristics, heavy metal fraction and distribution, and organic matter content in chicken manure compost. The results showed that the addition of different passivating agents significantly increased the pH in chicken manure organic fertilizer (P<0.05). The seed germination rate was increased after applying of passivation agents, being>80%, and the germination inhibition rate decreased accordingly, whereas the values of electric conductivity (EC) and organic carbon were inhibited. The total nitrogen content and carbon/nitrogen ratio (C/N) were lower than of those before composting, and all of the indicators reached the standard of organic fertilizer maturity. However, differences among the groups after composting were that the pH increase in the compounding treatment was comparatively higher, and that the EC decreased significantly under the treatment of the single sepiolite and calcium magnesium phosphate, whereas the total nitrogen content and C/N ratio of organic carbon were not significantly different in each group. Although the total amount of heavy metals in our organic chicken manure fertilizer increased due to a concentration effect, the proportion of exchangeable heavy metals in the fertilizer decreased, and while the ratio of the residual heavy metals increased. The passivation effect on heavy metals under combined treatments of different materials was better than that of a single agent, and the SNB treatment had the best effect on the passivation of Ni, Zn, As, and Pb. After composting treatment, the concentrations of humic substances (HS) and humic acid (HA) increased significantly (P<0.05), and the highest concentrations increased by 19.8% and 78.9%, respectively. The amount of fulvic acid (FA) decreased by 4.47%-20.11% compared with the initial conditions. Infrared spectroscopy analysis showed that the small molecular substances of polysaccharides increased after composting. In summary, the addition of a passivation agent can promote the heavy metal passivation in chicken manure organic fertilizers to potentially render the compost as harmless.

Suboptimal Temperature Acclimation Enhances Chilling Tolerance by Improving Photosynthetic Adaptability and Osmoregulation Ability in Watermelon

The temperature drop of plants from the optimal requirements can increase tolerance to severe chilling stress. Photosynthesis and osmoregulators were analyzed during chilling stress to explore the adaptation mechanisms that underlie the induction of chilling tolerance in response to suboptimal temperature. The relationships of these processes to suboptimal temperature acclimation in watermelon were then determined. Suboptimal temperature-acclimated watermelon plants demonstrated tolerance during chilling stress, as indicated by the decreased electrolyte leakage and malondialdehyde accumulation compared with those non-acclimated watermelon plants. Chilling-induced photoinhibition and reduction in CO2 assimilation rate were alleviated after suboptimal temperature acclimation. The xanthophyll cycle level was enhanced by improving thermal dissipation ability and avoiding light damage. Consequently, the chilling tolerance of suboptimal temperature-acclimated watermelon plants was enhanced. The osmoregulation ability induced by suboptimal temperature acclimation protected watermelon plants against chilling injury because of the accumulation of small molecular substances, such as soluble sugar and proline. The protein levels of Rubisco activase (ClRCA) and the gene expression of the Benson–Calvin cycle simultaneously increased in suboptimal temperature-acclimated watermelon plants during chilling stress. Chilling tolerance in watermelon plants induced by suboptimal temperature acclimation is associated with enhanced photosynthetic adaptability and osmoregulation ability.