Preparation of porous zinc oxide microspheres guided by HEPES

HEPES is abbreviated of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, which is a Good's buffer with pH buffer range of 6.8~8.2, and widely used in cell culture because of its good ability at maintaining physiological pH. It can also be used to prepare porous zinc oxide microspheres.

As a II-VI semiconductor compound, zinc oxide has a band gap of 3.37 eV and an exciton binding energy of 60 meV. Due to its special piezoelectric and optical properties, zinc oxide is widely used in many fields such as solar cells, sensors, and voltage sensitive resistors, piezoelectric materials, antibacterial agents, and photocatalysis fields. The morphology and size of zinc oxide have an important influence on its properties and applications, especially porous zinc oxide microspheres, which exhibit low density and high specific surface properties in catalysts, gas sensors, drug delivery and other fields.

At present, different methods have been reported to synthesize porous zinc oxide microspheres, such as high temperature calcination, chemical vapor deposition, and chemical bath deposition. However, these methods have high reaction temperatures, are complicated to operate, and are difficult to control. The solvothermal method is widely used for the synthesis of zinc oxide micro/nano materials due to its simple equipment and mild reaction conditions. However, the synthesis of porous zinc oxide microspheres by solvothermal method often requires the addition of a templating agent or a porogen. After the completion of the reaction, further post-treatment is required to remove the templating agent, which increases the complexity of the process and environmental pollution.

In order to solve the above problems, the researchers [1] developed a preparation method for porous zinc oxide microspheres by using HEPES molecules, which has low cost and simple operation, and the obtained zinc oxide has uniform morphology, high specific surface area and multi-stage pore structure. The specific operations are as follows:

(1) 2~6 mmol of organic zinc salt (zinc acetate or zinc acetylacetonate) are sonicated in 30~70mL organic solvent (TEG, DEG, EG, DMF) for 10 minutes, then add 2~8 mmol HEPES;

(2) The mixed solution is placed in a stainless steel high pressure autoclave lined with 100 mL of polytetrafluoroethylene, and reacted at 150°C for 6 to 18 hours;

(3) The obtained product was washed by centrifugation at 10000 rpm/min for 10 minutes, and the supernatant was removed, repeat 5 times to remove the residual solvent and HEPES. The product was dried in a 60°C oven for 24 hours and then naturally cooled.

In this method, HEPES molecules play an important role in the formation of porous zinc oxide microspheres. After the addition of the HEPES molecule, it is adsorbed on the surface of the nucleus by electrostatic interaction with the zinc oxide seed crystal in the sol. The presence of the HEPES molecule blocks further clustering and aggregation of the nucleus. Porous zinc oxide microspheres are formed by the continued growth of the HEPES molecules under solvothermal conditions. The HEPES molecules and solvent in the surface and voids of the microspheres can be completely removed after multiple washings with deionized water.

HEPES (CAS 7365-45-9) molecules have the advantages of non-toxicity and environmental friendliness. The method is easy to operate, simple in equipment, low in synthesis temperature, low price in raw materials, good in repeatability, and suitable for industrial production. The prepared porous zinc oxide microsphere has the advantages of uniform size, multi-stage pore structure (pore size 4~30 nm) and large specific surface area (43.4~69.6m2/g), and can be used as photocatalyst and gas sensor.

Reference

[1]CHEN Rong, LI Qin, YANG Hao, Lv Zhong. A preparation method of porous zinc oxide microspheres guided by HEPES molecularly. 2014, CN103482682A.

Edited by Suzhou Yacoo Science Co., Ltd.

Modification of zein functional drug-loaded microsphere with TRIS

As a common biological buffer, Tris(Hydroxymethyl)Aminomethane (TRIS) is not only widely used as a solvent for nucleic acids and proteins, but also as one of the main components of protein electrophoresis buffers. It can also produce a variety of chemicals and pesticides, pharmaceutical products, and it is an important intermediate for the preparation of surfactants, vulcanization accelerators and some drugs. This article will introduce another role of TRIS——modified zein functional drug-loaded microspheres.

As a natural hydrophobic macromolecule, zein has a wide range of sources, it is non-toxic, non-immunogenic, and has good biocompatibility and biodegradability. It is one of the few hydrophobic biopolymers that are allowed to be taken orally by the FDA：

(1) Its amino acid composition is very special, the proportion of non-polar amino acids is more than 50%. It can embed various substances such as polysaccharides. DNA, RNA, proteins, metal nanoparticles, quantum dots, oil droplets, and hydrophobic drugs;

(2) The amino acid residues on zein carry certain polar groups (such as ‐SH, ‐COOH, ‐NH3, and ‐OH), it provides the possibility to graft various functional molecules for chemical reaction sites and adapt to the complex and varied human environment.

Therefore, zein is an advantageous drug carrier material. However, the proportion of sulphur-containing amino acids in zein is only 2.8%, the ratio of basic amino acids is only 2.9%, and the proportion of hydroxyamino acids is 13.4%, which limits the selection of functional molecules and the effect of modification. To improve this, the researchers modified it with TRIS, including the following steps [1]:

(1) The zein and the amino protecting agent di-tert-butyl dicarbonate are dissolved in a specific dimethyl sulfoxide or ethanol aqueous solution at a mass ratio of 1:1~1.5:1, and protected from light at 25~40°C. The reaction is carried out for 12~24 hours to obtain a zein protection solution;

(2) Under the protection of nitrogen, add carbodiimide salt, N-hydroxysuccinimide and TRIS (CAS 77-86-1) to the zein protection solution, and avoid the light reaction at 25-40°C for 12~24 hours. To obtain a TRIS-zein solution;

(3) under the protection of nitrogen, adding concentrated hydrochloric acid to the tris-zein solution, and avoiding light reaction at 25-40°C for 6-8h;

(4) adjusting the pH to 5.0~6.0, transferring to a dialysis bag, centrifuging the retained solution in the dialysis bag, and lyophilizing to obtain TRIS-zein;

(5) Dissolving the hydrophobic drug and the lyophilized TRIS -zein in an aqueous solution of ethanol at a mass ratio of 1:1 to 1:10; and injecting hydrochloric acid having a pH of 2.5 to 4.5 under magnetic stirring. In the aqueous solution, after stabilization, the supernatant is centrifuged to obtain a drug-loaded microsphere;

(6) Functional modification of drug-loaded microspheres: separately prepare solutions containing different functional molecules, disperse the drug-loaded microspheres into a solution containing functional molecules, stir the reaction, centrifuge to remove the supernatant, and obtain functional drug carrying microsphere. The drug microspheres have a particle size of 100~300 nm and a drug-loading efficiency of 81.48~86.01%, and the grafting amount of the functional molecules is 1.72~1.94 times that of the unmodified zein microspheres.

The coupling of TRIS to zein significantly improves the physicochemical properties of zein. The prepared microspheres have good sphericity, uniform particle size distribution, high drug-loading efficiency, and are suitable for in vivo delivery. This research expands the application of zein in drug delivery systems and has a good application prospect in the field of medicine.

References

[1] Jiang Yanbin, Pang Jiafeng, Lu Shan, Li Zhixian, Trimethylolamine modified zein functional drug-loaded microspheres and preparation method. 2018, CN108403662A.

Edited by Suzhou Yacoo Science Co., Ltd.

How to distinguish the quality of the Sn-salt electrolytic coloring additives

According to our company's years of experience in the industry and customer feedback, we have learned that there are some problems in many Sn-Salt Electrolytic Coloring Agent in the market:

1.Many Sn-salt coloring additives contain benzene, which is a first-grade carcinogenic substance. The long-term use of Sn-Salt Electrolytic Coloring Additives containing benzene has great harm to the operating technical workers in the workshop. Severe coma, convulsions, and circulatory failure leading to death.

2. Poor stability and turbidity of tank liquid.

3. Coloring tank coloring background color is not stable. After the profile coloring, it is easy to have problems such as Yin and Yang and color unevenness.

The Sn-salt electrolytic coloring agent produced by our company is a new environmental protection product. It has avoided the common problems and has been well feedback by new and old customers.

1.Our company's formula absolutely does not contain benzene harmful substances.

2.This product is especially stable for tin sulfate and stable for pigmentation. It is the purest blue and yellow color system in the market, which is very clear and easy to grasp.

3.The color tank is colorless and transparent, as clear as water. Low cost, good quality, high yield. The tank is well maintained and the production wastewater is easy to be treated.

Our company is mainly engaged in the research, development, production and marketing of wastewater treatment chemical products (such as:Polyacrylamide,Alkali Aluminium Chloride,Chrome Removal Agentetc) and aluminum surface treatment chemical products (Neutralizing Agent,Sealing Agent etc)We use chemical reactions to decompose the pollutants in sewage, and always abide by the management concept of "Honesty first, Customer first, Quality first". We are always ready to do our best for you!

Principles for selection of sewage treatment processes

1. The main technical and economic indexes of process selection include: treatment of unit water investment, reduction of unit pollution investment, treatment of unit water consumption and cost, reduction of unit pollutant power consumption and cost, occupation of land, operation performance reliability, management and maintenance of the degree of difficulty, overall environmental benefits and so on.

2. Urban wastewater treatment technology should be selected according to the treatment scale, water quality characteristics, environmental functions of the receiving water body, local actual conditions and requirements, and selected after comprehensive technical and economic comparison.

3. It is necessary to determine the influent water quality of sewage, optimize the parameters of process design, and make a detailed investigation or determination of the current water quality characteristics of sewage, and make a reasonable analysis and prediction. The composition of water quality is complex. When special, the dynamic test of sewage treatment process should be carried out, and the pilot study should be carried out if necessary.

4. The new process should be adopted actively and prudently. For the new process that is applied for the first time, it must pass pilot test and production test, and provide reliable design parameters before application.

5. In the construction of the same sewage plant by stages, the same process should be adopted in each stage, and the construction scale of each stage should be the same as possible.

Related reading:Aluminium Chloride for Sewage Sludge Dewatering

Technology of waste Water Recycling and treatment in Printing and dyeing Industry

Printing and dyeing industry uses a large amount of water.Usually,the water consumption of 1 ton of textile for each printing and dyeing process is 100 ~ 200 tons, of which 80% of the dyeing wastewater discharged. Commonly used printing and dyeing wastewater treatment methods are recycling and harmless treatment.

Recycling is divided into three aspects:

1. The wastewater can be recycled according to the characteristics of water quality, such as bleaching and cooking wastewater and dyeing printing wastewater can be recycled separately, the former can be used for convection washing.

2. The recovery and utilization of alkali liquor is usually recovered by evaporation method. If the amount of alkali liquor is large, it can be recovered by evaporation. The amount of alkali liquor is small and can be recovered by evaporation of film.


3. The recovery and utilization of dyestuffs, such as the acidizing of the sulphide acid, colloidal particles, suspended in the residual solution, and recovery and utilization after precipitation and filtration.


There are three different methods for the innocuous treatment of printing and dyeing wastewater:

1. Physical treatment including precipitation and adsorption, and so on. The precipitation method is mainly used to remove the suspended matter in the wastewater, and the adsorption method is mainly used to remove the dissolved pollutants and decolorization.

2. Chemical treatment including neutralization, coagulation and oxidation, etc. The neutralization method can adjust the PH of wastewater and reduce the chroma of wastewater。The coagulation method is to remove disperse dyes and colloids from wastewater.The oxidation method is to oxidize the reducing substances in waste water and precipitate vulcanized dyes and vat dyes.


3. Biological treatment including activated sludge, biological turntable, biological drum and biological contact oxidation, etc. In order to improve the effluent quality and meet the discharge standards or recovery requirements, it is often necessary to adopt several methods of combined treatment.



Related reading:High Quality Wastewater Treatment

How SCR technology works?

AdBlue  DEF is a consumable that must be used in SCR technology.

SCR technology uses a catalyst system can effectively reduced the emission of nitrogen oxides and solid particles produced by diesel engines into nitrogen and water.The main components of the SCR system include the catalyst, the AdBlue injection unit, the urea tank and the AdBlue dose controller.

Process of SCR technolog : the urea tank automatically ejects the AdBlue (diesel exhaust fluid ) when nitrogen oxides are found in the exhaust pipe and the oxidation-reduction reaction of AdBlue and nitrogen oxides in SCR catalytic reaction tank produces non-pollution nitrogen and water.

With the intelligent control of SCR system, the car will be unable to start when the AdBlue in the urea tank is insufficient .In order to ensure the normal running of the vehicle, there should be sufficient AdBlue for the vehicle.

TRIS, Bis-Tris, Tricine, TES, TAPS, What is the difference in application?

TRIS(Tris(Hydroxymethyl)Aminomethane), Bis-Tris, Tricine, TES, TAPS are buffers commonly used in biochemical experiments and molecular biology experiments, and they all contain the structure of TRIS. Then what are the differences in application between these buffers?

We hope that the following table could solve your doubts.

Table 1. The application of TRIS, Bis-Tris, Tricine, TES, TAPS

In specific use, buffers containing the TRIS (CAS：77-86-1) structure will form a strong or weak complex with a variety of metal ions, so the stability constant should be taken into account. In addition, the buffer range and the appropriate type of experiment also should be considered in order to obtain the best experimental results.

Edited by Suzhou Yacoo Science Co., Ltd.