Turkey this year has become the largest importer of non-monetary gold from Venezuela.
Before the encounter between the two world leaders, Kremlin spokesman Dmitry Peskov refused to give reporters at a press conference a number on Russian investment in the country.
Erdogan and Maduro signed a series of agreements in the areas of mining, commerce and oil.
Maradona, who has gone on record with his support of Maduro's leadership of Venezuela in recent months, once again backed the president after an explosion in Caracas close to an event where the president was giving a speech.
"Trade restrictions and sanctions are wrong", Erdogan said, warning that such measures would only deepen "instabilities".
Maduro has become increasingly isolated in the world under growing sanctions led by the US and the European Union which accuse him of undermining democratic institutions to hold onto power, while overseeing an economic and political crisis worse than the Great Depression.
One of the agreements formalizes cooperation between the state-owned oil companies Petróleos de Venezuela S.A. (PDVSA) and the Turkish Petroleum International Company, in addition to an agreement to avoid double taxation and tax evasion.
The United States and some European nations have sanctioned Maduro's administration in an attempt to pressure Venezuela into making a return to democratic ways.
"Political problems can not be resolved by punishing an entire nation", said the Turkish head of state.
Maduro said Turkish businesses intend to invest some 4.5 billion euros in its OPEC partner.
According to data released by Coin Dance, transactions in BTC in the country reached 1,284 BTC ($5.1 million).
Massive inflation and a shortage of basic commodities such as foodstuffs and medicine have forced an estimated 2.3 million Venezuelans to immigrate to other South American countries.