1. BIOLOGICAL BATTERIES
Mitochondria, often called the powerhouse of the cell, is a biological battery that could one day
power small portable devices like mobile phones or laptops.
Mitochondrial charge comes from the difference of potential between inner and outer
mitochondrial membrane. What we call respiratory chain is a biological system meant to separate
electrons from their atoms, thus pumping electrons on one side of a membrane, while protons are
left on the other side, creating a charge (polarization). Unlike our batteries (based on lithium),
the mitochondrion uses hydrogen ions (protons).
In the mitochondrial electron transport chain electrons move from an electron donor (NADH or
QH2) to a terminal electron acceptor (oxygen) via a series of redox reactions. The resulting
transmembrane proton gradient is used to make ATP via ATP synthase ( oxidative
phosphorylation). This is called the chemiosmotic coupling hypothesis which was proposed by
Peter D. Mitchell (Nobel Prize in chemistry). Electron transport chain and oxidative
phosphoylation are coupled by a proton gradient across the inner mitochondrial membrane.
The efflux of protons from the mitochondrial matrix creates an electrochemical gradient. This gradient is used by the
ATP synthase complex to make ATP (energy).

2. The generic image of mitochondrial electron separation is shown in this picture.
Mitochondria convert fatty acids and pyruvate, formed from the digestion of sugars and fats,
to adenosine triphosphate (ATP), the cell's energy supply. Along the way a tiny electrical current
is generated.
Shelley Minteer and coworkers from Saint Louis University in Missouri, US, have been able to
gather the flowing electrons and put them to work in a new biological battery.
Minteer notes that commercially available batteries contain metals, and need to be recycled.
However, battery recycling facilities aren't widespread in many areas. 'My research is about
transitioning from these metal-based batteries to a biological battery,' she said. 'The living cell
does energy conversion very efficiently.'
Her research in organelle-based bioelectrocatalysis is focused on the use of mitochondria to
catalyze the complete oxidation of pyruvate and fatty acids at the anode of fuel cells as well as
the unique biochemical properties of mitochondria that allow it to be used in biological energy
use .
Similar to a traditional battery, the bio version contains two electrodes. The cathode houses the
conversion of oxygen to water, while the anode holds the immobilised mitochondria. Once the
substrate comes in it can be completely oxidised to carbon dioxide, and when that happens,
electrons go through the wire and do work.
The bio battery is completely renewable and biodegradable, and is stable at room temperature
and a neutral pH for up to 60 days.
Other groups are trying to replicate the electrocytes used by the electric eel.
The research began by studying the biochemistry of eel voltage generation, based on ion
channels. The researchers were able to replicate artificial ion channel models for power output
and energy conversion.
How do mitochondria store energy?

3. Almost everybody agrees that younger people and children possess more energy than the elderly.
Until recently this empiric observation could not be explained in scientific terms. Since
mitochondrial medicine was launched in the 2000, much has been clarified in terms of this
cellular powerhouse. It is a common knowledge now that cells contain from a few to thousands
of mitochondria, depending on their energy needs. Because mitochondrial DNA is prone to more
damage than the nuclear DNA and has fewer repair capabilities, mitochondria are being depleted
as we age. The reason elderly have less energy than young people and children is because they
have fewer mitochondria. Neuronal mitochondria are depleted even more because the brain
lacks sufficient antioxidant mechanisms. The CNS uses 25% of the body oxygen, but it does not
have a proportionally increased concentration of antioxidants to counter this load. As such, the
brain is vulnerable to high levels of oxidative stress.
Mitochondria, the main target of oxidative stress in susceptible neurons, were found to be
significantly decreased in number in Alzheimer’s Disease (AD), suggesting that oxidative stress
may be fundamental to the development of this neurodegenerative disease. Additionally the
absence of neurofibrillary tangles in neurons exhibiting mitochondrial damage and energy
deficiency places mitochondrial abnormalities as the earliest cytopathological changes in AD.
Another common change is the reduced numbers of microtubules in AD, which impair
mitochondrial transport to the axon. The structural and functional abnormalities, found in
neurons lacking neurofibrillary tangles, confirm that mitochondrial damage is a primary
pathology of Alzheimer’s disease.(Brain Protection in Schizophrenia and Mood Disorders,
Michael S. Ritsner, 2010).
The mitochondrial energy is stored in hundreds or thousands of mitochondria per cell multiplied
by trillions of cells. This clean energy could very soon power our computers, cameras and some
home devices.
ADONIS SFERA, MD