Research Progress in Preparation of Oxidized Cellulose

Cellulose is the most abundant natural polymer material in the world.Cellulose is diffi-cult to dissolve because it contains a large number of inter molecular hydrogen bonds.Therefore,the modification of natural cellulose by chemical oxidation can expand its application field.The oxidation process of cellulose is focused on,the oxidation methods and research progress of cellulose are introduced,and further development direction of oxidized cellulose is prospected.

Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

The 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)oxidized cellulose film(TOCF)has been attempted to be used as a substrate in electronic and optoelectronic devices,but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication.In this study,TOCF was treated in different atmospheres(air,vacuum,and N2)and at different temperatures,and the properties were investigated.The results indicate that the optical properties are slightly affected by atmosphere and temperature;only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃.In contrast to the slight effects on the optical properties,cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃.Specifically,TOCF was exposed to air,followed by N2 and vacuum atmospheres.Additional Fourier transform infrared(FT-IR)and nuclear magnetic resonance(NMR)results showed that increasing the temperature had no significant effect on the structure of TOCF.Therefore,the annealing temperature should be controlled at a temperature of lower than 100℃and a vacuum atmosphere is preferred.

Oxidizing Cellulose to 2,3-Dialdehyde Cellulose by Sodium Periodate

Study on oxidizing cellulose to 2.3-dialdehyde cellulose by sodium periodate （NalO4） was carried out. The effects of reaction conditions such as pH of solution, temperature, oxidant concentration, oxidation time. the particle size of 2,3-dialdehyde cellulose and alkali treatment temperature on the dialdehyde concentration ot cellulose were investigated in detail, The results show that the aldehyde group content was created while reaction temperature and alkali treatment temperature increased. The most principal factors affecting the aldehyde group content of 2,3-dialdehyde cellulose were found out and the best oxidation conditions were as follows： the pH was 2. the reaction temperature was 45℃. the mass ratio of cellulose to NalO4 was 1/2, the reaction time was 4 h, the alkali treatment temperature was 70℃ and smaller particle size was 0.80 mm.

Implantable versatile oxidized bacterial cellulose membrane for postoperative HNSCC treatment via photothermal-boosted immunotherapy

The recurrence of head and neck squamous cell carcinoma(HNSCC)after surgical resection continues to pose a major challenge to cancer treatment.Advanced HNSCC exhibits a low response rate to immune checkpoint blockade(ICB),while photothermal therapy(PTT)can increase the infiltration of immune cells to make tumors more susceptible to cancer immunotherapy.In this regard,we designed and constructed a novel multifunctional nanocomposite comprised of oxidized bacterial cellulose(OBC),thrombin(TB),and gold nanocages(AuNCs)containing anti-programmed death 1(PD-1)antibody(αPD-1@AuNCs),which allows the combination of therapies with remarkable postoperative antitumor immunity to control local tumor recurrence.TheαPD-1@AuNCs displayed high light-to-heat conversion efficiency and induced pyroptosis under near infrared(NIR)irradiation,which activated a potent antitumor immune response.More importantly,the therapeutic system could induce tumor pyroptosis and enhance antitumor immune response by increasing T-cell infiltration and reducing the immune suppressive cells,when combined with local ICB therapy,which effectively avoided the tumor recurrence in a HNSCC postoperative mice model.Overall,the newly developed multifunctional nanocomposites could be a promising candidate for the treatment of postoperative HNSCC.

Critical impact of nanocellulose on the synthesis of porous cellulose monolith with oriented microchannels:Structure control,mechanics,mass transport

Nanocellulose harvested from biomass has attractive properties that have promoted research on its practical applications.Herein,we investigated nanocellulose-based porous monoliths with oriented microchannels that can be fabricated via a unidirectional freezing method.In this method,water-dispersed cellulose nanofibers(CNFs)were immersed into a cold source at a controlled speed,followed by subsequent freeze-drying.The structure of porous cellulose monoliths mainly depends on two factors:the freezing conditions and properties of the dispersed CNFs.The former has been investigated previously.However,the effects of the latter remain unclear.In this study,CNF suspensions prepared by 2,2,6,6-tetramethylpiperidine-1-oxylmediated oxidation cellulose nanofibers(TOCNs)with different aspect ratios and concentrations were used.The effects of these variables on the resulting structure,including the pore shape,size,wall thickness,were examined.Based on the results,the impact of TOCNs on the structure of porous cellulose monoliths was investigated.Our findings suggested that depending on their structure,the porous cellulose monoliths exhibit different mechanical strengths and mass transport properties.In particular,porous cellulose monoliths synthesized from 5.1 wt.%short TOCNs exhibited a low density(55.9 mg∙cm^(−3)),high mechanical strength(8687 kPa),fast mass transport.