Drug Delivery superhero

Really glad to have attended the lecture by none other than MIT’s professor Robert Langer on 30th April 2018 held at SUTD (Singapore University of Technology and Design). Having worked on my PhD more than a decade ago on the topic of “controlled release devices using supercritical fluid technologies”, you can imagine that his pioneering work on polymeric controlled release devices inspired me and so many other researchers in this field at that time. I believe that it is fitting to name him as the grandmaster of drug delivery research.

Professor Robert Langer

My earlier work on supercritical fluid technologies for drug delivery include looking at the particle formation via supercritical antisolvent processes with paclitaxel as the model drug for sustained release demonstration. In more recent development, I have also worked with fabrication of microporous biopolymeric foam using supercritical CO2 foaming which can be used for applications in drug delivery, protein delivery, tissue engineering and etc.

Today, I am still actively in pursuit of my research interest in supercritical fluid technologies, but i have moved on to applications of food product processing, waste processing and sustainable development. Professor Bob Langer’s work is a perfect demonstration of the important and wonderful outcomes of a multidisciplinary research, where the fundamental principles in heat and mass transfer used in Chemical Engineering is used to solve problems in medical and biomedical fields.

His talk on the development of his research over the decades certainly inspired me and reignited my interest in polymeric drug delivery applications using supercritical fluid processing. Particularly, i believe that supercritical fluid processing provides opportunity for solvent-free product and process development and its unique qualities such as low processing temperature, tunable solubility and etc. has great potential on larger scale pharmaceutical and biomedical applications.


NewRIIS opening

Following the congregations ceremony on 1 November 2017, Newcastle University in Singapore’s very own Research and Innovation Center (Newcastle Research and Innovation Institute: NewRIIS) held its official opening on 2 November 2017 at the newly furbished facility at Level 5 Devan Nair Institute (E2i). At the opening, we have the opportunity to showcase some of our ongoing research projects to guests and industrial collaborators.

At the opening, I had the chance to display some of my recent projects on supercritical carbon dioxide processing and its potential applications. Many exciting conversations on further development and collaboration popped up on this very fruitful event.


With Great Properties, Comes great opportunities!!

Congregations 2017

1 November 2017 marks the day our 5th batch of Newcastle Chemical Engineering Degree Programme students in Singapore graduates. Watching the students struggle, progress, grow and finally getting the degree that they have worked hard for always gives me a sense of satisfaction and gratefulness that I have the opportunity to be part of their journey.



Red or Blue?

“Red or Blue?” was the very important question that my husband, LR, so urgently needed to ask me at the outlet mall one weekend (We love to go to the outlet mall). LR was browsing through the items on sale at the Adidas outlet mall and found this sports t-shirt on sale. As usual, the choice of 2 colors has put him in a dilemma.

I took a look at the t-shirts and what caught my eye was not the color nor design, but the words printed at its back “DryDye”. What is DryDye technology? As far as we know, dyeing of textile produces tonnes of wastewater which requires energy intensive processes to treat and recycle. After dyeing, the textile need to be dried and that further requires more heat and energy. DryDye refers to the technology which uses almost zero amount of water to dye the T-shirt. How is this done?

The answer is in Carbon Dioxide. Often associated with bad press due the links of rising temperatures and atmospheric CO2 levels, it is a highly misunderstood gas. The problem is not in the gas itself, but in its uncontrolled release into the environment from the energy and processing industries. At normal conditions, carbon dioxide behaves like any normal gas. However, once subjected to temperature and pressure higher than its critical point (31.1deg C and 73.8bar) in a specialized chamber, it transforms into a supercritical fluid with supercritical properties.

Textile dyeing takes place when the dye chemicals are deposited onto the textile material. In conventional dyeing process, we need to dissolve the dyes in water, and then allow the water with dissolved dyes to penetrate into the material and deposit the dyes onto the fibres of the textile. In Supercritical dyeing, the dyes are dissolved directly in supercritical carbon dioxide (CO2), which has the ability to swell and penetrate effectively into the fibres in the textile and depositing the dye molecules onto the fabric. The beauty of this process is that the final dyed textile is dry, thus eliminating the energy consuming drying step. Supercritical CO2 carrying the residual dyes exiting the system can be easily separated by lowering the pressure of CO2 from supercritical to below critical.

DyeCoo, one of the FeyeCon’s spin-off has been very successful in developing the waterless dyeing technology and working with many Multinational corporations to deliver sustainable textile dyeing solutions.

Daddy DryDye

In the end, my answer to the most important question in the universe at that time was “Red, because you can wear it during Chinese New Year”.

Visit to Supercritical Fluid Center 2017

Visited the Supercritical Fluid center in Malaysia during a trip to KL in September, attending a Chemical Engineering Design Project Workshop organized by IChemE Malaysia.

Very thankful for the warmth and hospitality of the hosts Dr Chong Gun Hean and Ms Fizreena. Looking forward to going back to deliver the seminar talk that was postponed due to the extra public holiday on 4th September. Visit to SFC


In our earlier chapter on the application of supercritical CO2 for microencapsulation, we have described the mechanism of using Supercritical Antisolvent Method (SAS) for co-precipitation of biopolymers and drugs to achieve controlled drug delivery systems. Such applications have great potential in development of sustained drug formulations that can more efficiently deliver the right dose of medication to the patient over a prolonged period, therefore enhancing patient’s overall quality of life and medical treatment.

Besides applications in pharmaceutical products, supercritical girl is actually very interested in further development of Captain Encapsulation’s capabilities to serve the food and nutraceutical industry, especially the local industries and also for Traditional Chinese Medicinal (TCM) ingredients. Mainly looking at thermally labile, or high anti-oxidation content ingredients and methods to process food-grade encapsulating materials with minimal or zero usage of harmful solvents to create safer, better functionality, hopefully cheaper food ingredients that serve to provide health benefits to consumers.


In the recent Food Science and Technology Conference organized by Nanyang Polytechnic in Conjunction with UCDavis and Jiangnan University, Supercritical Girl presented a poster highlighting part of the work with students from National University of Singapore (NUS) about Supercritical carbon dioxide processing for food and ingredient micronization and microencapsulation applications. It was a very insightful event and supercritical girl made a few new friends and met up with some interested collaborators.

Carbon Dioxide: The unexpected Superhero

Carbon dioxide is all around us! While it has been widely regarded as a problem to the environment and largely responsible for climate change, there is actually another lesser known side to CO2.


Carbon dioxide is one of the most commonly utilized supercritical fluid in the industry. The supercritical state is one in which the fluid exists above its critical temperature and pressure. For CO2, the critical point is 31.1 degC and 73.8bar. The low critical temperature of CO2 allows processes to be developed at mild temperatures (e.g. at 35 degC).

So how exactly can CO2 be a Superhero? Firstly,  we are all familiar with the geeky, spectacled young man who rushes into a phone booth and turns into a superhero. Well, CO2 enters a high pressure chamber as a normal fluid and in a short time after reaching it’s critical conditions,  turns into a supercritical fluid!


To find out more about how the supercritical properties can be used to provide sustainability, improve product quality AND in turn save you some money$$, stay tuned for more updates.

Captain Encapsulation


Captain encapsulation is one of the very first member of THE SUPERCRITICALS. Armed with the ability to remove harmful organic solvents effectively, Captain Encapsulation is committed to protect the weak and vulnerable with a layer of protection. (E.g. heat and oxidation sensitive ingredients can be microencapsulated in biocompatible coating material to provide stability and improve shelf life)


Microencapsulation by supercritical CO2 can be achieved by Supercritical Antisolvent (SAS) process or the supercritical Spray drying process.

Simplified schematic for the Supercritical Antisolvent (SAS) process

In SAS, a solution of the coating material and active ingredient dissolved in a suitable organic solvent (e.g. ethanol, dichloromethane, ethyl acetate, etc) will be sprayed into supercritical CO2. The supercritical CO2 removes the bad guys (organic solvents) in a FLASH and the active ingredient is saved (co-precipitated out) in the CO2.


Microencapsulation offers excellent opportunities for masking!


Taste masking, color masking or odor masking of active ingredients can help to improve consumer acceptance.

In addition, microencapsulation can also be applied for controlled delivery systems where a long-term or a trigger-controlled release (by pH or temperature) is desired. Applications in controlled release systems investigated include paclitaxel (a hydrophobic anticancer drug) in PLA and Curcumin in Eudragit L100 (Generous gift from Evonik Industries).

Samples of: 100% EL100 (white); 1% curcumin in EL100 by SAS; 2% curcumin in EL100 by SAS ; 100% curcumin (Bright orange)

More information can be found in the references below:

  1. L Y Lee, C.H. Wang, K.A. Smith, “Supercritical antisolvent production of biodegradable micro- and nanoparticles for controlled delivery of paclitaxel”, Journal of Controlled Release, 125, 96-106 (2008).
  2. L Y Lee, KA Smith, C H Wang. Paclitaxel-loaded Poly L Lactide prepared by Supercritical Antisolvent methods. Singapore-MIT Alliance Annual Symposium, Singapore, Jan 2006
  3. L Y Lee, K A Smith, C H Wang. Nanoparticle fabrication of biodegradable polymers using supercritical antisolvent: Effects of mixing and thermodynamic properties. AICHE Annual Meeting, Ohio, USA, Nov 2005